"Prehistoric America - 1x01 21st century, North America," "where people have reached even the remotest corners of the continent and pushed back the boundaries of modern technology." "But it isn't so long since humans first set foot here, about 14,000 years ago." "And back then North America belonged to other creatures of the size to match this vast land." "Giants whose lives are now lost in the shadows." "Imagine if we could travel back in time to the end of the last Ice Age, long before the first city was born" "to look through the eyes of the very first people" "and experience a wild new world." "In this series we will take you on a journey back into the past to build a picture of how things were at the end of the last Ice Age," "14 thousand years ago." "By searching for evidence that still survives today we reconstruct the landscape and the wildlife of prehistoric North America." "During the last Ice Age massive glaciers covered half of North America." "But to the far north west there was a land that remained free of ice." "This land was called Beringia and it ranged from what we now know as the Canadian Yukon and Alaska across to Siberia in the west." "NA was only colonized by people around 14,000 years ago." "And Beringia is believed to be the starting point from which they spread out across the continent." "In this programme we'll go back to where it all began." "What was this wild new world really like when it was still the Land of the Mammoth?" "These mountain glaciers in the Canadian Yukon are relics of the great ice sheets that reached their peaks some 20,000 years ago." "The Yukon and its neighbour, modern day Alaska, were once part of the land that was Beringia." "Stunning though this region is today, it's just a shadow of the world that was encountered by the first Americans." "Underground, the soil is frozen solid as it has been ever since the Ice Age." "Locked within this permafrost, are vital clues to help us recreate the ancient wildlife of Beringia." "Even today Alaska's rivers wash intriguing traces of the past out of the permafrost." "So who did this titanic tusk belong to?" "Beringia's largest resident" " the woolly mammoth." "Weighing six tonnes or more, the woolly mammoth was about the size of a bull African elephant today" "and it had equally impressive Ice Age neighbours, some of which survive here almost unchanged, and some of which can still be found elsewhere." "Although 14,000 years is long enough to see enormous climate changes, in evolutionary terms it's just the blink of an eye." "Beringia was a world where familiar North American animals lived alongside prehistoric giants." "Of all these creatures, the woolly mammoth is the undisputed symbol of the Ice Age." "But what do we really know about how this giant lived?" "How did it use its massive spiral tusks?" "Modern day elephants, who are mammoths' closest living relatives, may provide some answers." "They use tusks to break and lever branches in their search for food," "and also to dig for minerals, which all leaves telltale scratches on their tusks." "Similar marks found on mammoth tusks suggest they, too, were used as tools." "But these tusks are huge." "They reach 4 metres long and can weigh more than 80 kilos, equal to a full-grown man." "So why were mammoth tusks so big?" "Bull elephants fight for the right to mate." "The strongest males win access to the females and pass on their genes." "It was the same for mammoth bulls." "And over time this competition led to the development of ever larger tusks." "Sheer size didn't save the mammoth from extinction." "But another of Beringia's woolly beasts is still around today:" "the musk ox." "Like other Ice Age survivors, musk oxen have hardly changed in 14 millennia." "Every autumn males compete to father young until a single dominant bull emerges in the herd." "An Ice Age drama unfolds as rivals thrash out threat displays." "The two bulls size one another up by walking in ritualised circles." "A brief chase and the matter is resolved." "The winner takes all." "While the musk ox still survives in North America, many of Beringia's other Ice Age mammals are now extinct." "But like the mammoth, they left clues locked within the permafrost." "Gold miners in Alaska use high-powered water jets to thaw the permafrost in search of gold." "But every now and then they hit another kind of treasure." "In one remarkable discovery, recreated here, the head and hide of a large carcass was exposed, a unique opportunity to scientists to tap some Ice Age secrets." "The remains were of an extinct steppe bison, along the horned relative of the North American bison of today, an adult bull that must have died being immersed in silt and mummified by the cold for thousands of years." "Thick fat deposits found under the skin suggested that the bison did not starve to death, and deep wide scratch marks hinted at a violent end." "An Ice Age predator killed the bison." "But which one?" "Wolves are the bison's major predators in North America today and they were certainly around during the Ice Age." "Could they have been responsible?" "Wolves hunt in packs surrounding prey and gradually exhausting it through constant hurrying and nipping." "But there's no way they could have made these marks." "What about the grizzly bear, another meat-eater that was around in prehistoric North America?" "The grizzly can be an impressive hunter, but during the Ice Age there was another, even bigger, bear " "the Giant Short-Faced Bear - the biggest bear that ever lived." "So could a bear have made the scratch marks on the goldmine bison?" "Bears have long claws, but they get worn down by the daily grind moving around and rooting for food." "They're just not sharp enough to rip into the bison's hide." "To solve this puzzle we need to look to Africa." "African buffalo are similar in size to the extinct steppe bison." "So what is their foremost predator?" "The lion." "Lions, unlike bears, have their claws sheathed most of the time to keep them razor-sharp." "But when they strike their claws extend to get a good grip on the victim's hide." "This often leaves deep gauges just like those found on the mummified bison." "And there's a second clue:" "the most efficient way to kill large prey is suffocation." "Lions typically clamp their jaws around the victim's muzzle in a deadly bite." "Our Ice Age bison had a set of puncture marks on its snout, around 9 cm apart, the blueprint of a lion's bite." "The third and final clue was found embedded in the bison's hide, a tiny fragment of lion tooth." "So it seems the king of the savannah once roamed the cold expanses of Ice Age America." "These long-lost lions of Beringia were close relatives of those we find in Africa today, but they were up to 25 percent bigger, amongst the largest lions that ever walked the Earth." "Thanks to the bison herds and other big game they could flourish in the freezing north." "But the lion's family tree begins in Africa." "so how did they end up here?" "The answer lies in the effects of North America's immense and fluctuating ice sheets." "As they grew, they locked up so much water that the sea levels began to fall." "The Bering Sea between Asia and North America began to drain away, leaving a bridge of land exposed, the Bering Land Bridge, roughly a thousand miles wide and covering an area twice that of modern Texas." "This was the route by which lions, woolly mammoths and other creatures colonised the American continent." "During the last Ice Age the Bering Land Bridge formed once more and this time it allowed a different colonist across, one that would have a huge and permanent effect upon the continent." "This is one of their first known haunts - the Mesa site in northern Alaska, a key point on the Ice Age map." "Beautifully crafted spear points found here are known to date back almost 14,000 years and tell us that the first people to cross the land bridge were skilled sophisticated hunters." "But what were they doing on this particular spot?" "The climate was harsh, the location extremely exposed." "It's not a place you choose to make a campsite." "But if you were a hunter what you need it was a view." "The Mesa was the perfect lookout point with panoramas of surrounding land and game." "These early hunters had spread all the way from Asia." "What did they find on the other side of the Bering Bridge?" "This is Alaska today - a wetland of forests, boggy tundra, lakes and rivers;" "rivers that still churn out fresh clues to the Ice Age past." "This is a brick-size tooth." "And it belonged to a woolly mammoth." "Its narrow ridges of enamel tell us more about how mammoth lived." "Studies of modern elephants suggest that the more grassy weed, the more ridges you need, and mammoth tooth had even more ridges than those of any elephants." "It seems that mammoths fed almost exclusively on grass, they were gargantuan grazers." "Fossil bones help draw a picture of another well known grazer, a kind of horse." "Wild horses live in small herds and Beringia would have been the scene of vicious battles between rival stallions." "But Beringia's horses are now gone." "Today their closest living relatives roam the open steppes of Central Asia." "Like mammoths, horses are predominantly grazers." "The fact that both horses and mammoths were here suggests these forests weren't." "It seems that 14,000 years ago" "Beringia was a huge expanse of open grassland." "This unique habitat of cold dry grasslands is known as mammoths' steppe." "But that's not how the region looks today." "So why is it so different?" "14,000 years ago the climate here was heavily influenced by the vast blankets of ice to the east." "At its maximum the ice covered nearly 6 million square miles and in places it was up to two miles thick." "The ice blanket was punctuated only by occasional islands of rock, the peaks of the very highest mountains." "Though Beringia itself remained largely ice-free it still felt the effects of the ice sheets - cold dry air flowed down the glaciers and out across surrounding lands." "The freezing dry winds blasting off the ice created conditions in which only grasses and other small plants could flourish." "There were advantages:" "the wind also prevented snow from building up so grass remained accessible throughout the year." "In such cold temperatures this was a lifeline for the mammoths, bison and other grazers," "which in turn sustained other beasts of Beringia." "Another widespread Beringian animal that depended on the Ice Age wind was the Dall sheep." "Dall sheep needed the snow to be blown clear from their winter grazing and today they have the same priority." "They're found only on the most exposed and windswept mountain slopes." "In the autumn Dall rams, like the mammoths and the musk oxen, become focused on their urge to mate." "The male flicks the air with his tongue to test if the ewe is receptive." "The next stage of courtship is not so subtle - he gives her a kick." "At this highly charged time of year skirmishes can easily erupt between the rams," "especially if they both have the same ewe in their sights." "But though there was food in Beringia, it was still cold, bitterly cold." "For much of the year temperatures would have remained below freezing 24 hours a day." "How did the Ice Age animals survive in such a harsh world?" "The more hair the better for a start." "Musk oxen can stay warm in temperatures of -50 degrees centigrade." "thanks to their chill proof woolly coats." "In fact, they have the warmest fur of any mammal." "They have an extremely long outer layer over another very dense fine wool layer beneath, a combination so effective that even in winter the musk ox can overheat if it runs too far." "From frozen mammoth remains we know they had a very similar fur coat made up of strands of hair up to a metre long." "Small ears also help to minimize heat loss, the opposite effect of those huge heat dispersing ears of their relatives, African elephants." "Other Beringian animals had more than a fur coat to help them cope with cold." "This skull belongs to the bizarre looking Saiga antelope," "one of the less familiar faces of the Ice Age scene." "Like the musk ox," "Saiga have a thick winter coat of hollow hairs for extra insulation." "But they have another adaptation all of their own - an enormous bulbous nose." "The nose is shaped like this because it contains large which pre-warm cold air while breathing in and retain pressure's moisture before breathing out." "So Saiga, too, were well equipped to live in a cold dry climate of Beringia." "Today, they're only found in another bleak environment - the steppes of Central Asia." "Some Ice Age animals took a totally different approach to surviving in winter." "Arctic ground squirrels feed up in autumn building up as much body fat as possible, almost doubling their weight." "As the first snows fall they retreat to their underground burrows and bypass the winter entirely." "Arctic ground squirrels hibernate like other small mammals, but with a unique twist - they can lower their body temperature right down to almost -3 degrees centigrade." "But thanks to our biochemical supercooling process they don't actually freeze." "Every few weeks they warm up temporarily through bouts of shivering, which probably helps to ward off permanent brain damage from the cold." "This deep sleep tactic helps the ground squirrels to conserve energy, but it's a high risk strategy." "and some just don't wake up." "30,000 year old frozen ground squirrels have been discovered still preserved in their underground tombs." "Every inhabitant of Beringia had to have its own way of dealing with the cold and that included those first people who arrived across the Bering Land Bridge." "They knew how to make weapons and cooperate to hunt for food." "They made weather proof clothing out of animal hides and had fire to keep them warm." "Without these skills they couldn't have survived the endless winters." "But spring bought easier times and excellent hunting opportunities." "Spring was when Beringia's big game gave birth to their young." "For these baby animals it was a race to go up over the brief summer to be tough enough to face the winter." "One young animal that died in its first winter was discovered in the permafrost of an Alaskan goldmine." "Recreated here are the best mummified remains of this animal ever found in North America." "It's a baby woolly mammoth and from its size we know it was less than a year old." "But did it starve to death or was taken by a predator?" "Perhaps young elephants provide some clues." "They stick close to their mothers' side for more than a year." "And they also have backup - a family group of very protective sisters and aunts." "Even lions will think twice about approaching adult elephants." "And with the babies so well guarded they really get a chance to strike." "Starvation during its first bitter winter is more likely to have killed our baby mammoth." "Perhaps its mother could not provide enough warm milk." "Only part of the body remains." "The hindquarters were eaten." "There were plenty of scavengers around 14,000 years ago." "There were foxes, wolves and grizzly bears." "But back then they had serious competition from the Giant Short-Faced Bear." "The Short-Faced Bear's bone chemistry reveals it was a carnivore, at up to a tonne probably the largest meat-eating mammal that ever walked the Earth." "On its long legs it ranged great distances across the open steppes in search of food." "We also know from fossils that it had broad nostrils and an acute sense of smell." "But with its powerful bone crunching jaws it's now believed the Giant Short-Faced Bear was primarily a specialist scavenger rather than a predator, feeding on the victims of this unforgiving world." "The Short-Faced Bear was just one of the many extraordinary beasts that roamed the Ice Age steppes." "Clues in the landscape and the wildlife of today have given us an insight into what that long-lost land was like." "Now imagine that we can really travel back 14,000 years and stand with those first hunters on the Mesa." "Look out on that Ice Age world and experience a day in the life of Beringia." "This is what it might have been like." "Beneath us the steppes stretch away to the mountains." "It's only winter and a time to feed up ready for the long cold months ahead." "Bison, Saiga antelope and other grazers throng the flats below the Mesa." "Musk oxen and Arctic hares are well insulated against the cold as are the largest grazers of them all - the woolly mammoths." "This herd is regrouping, ready for a long day feeding on the grasses beneath the snow." "Mothers need to keep milk flowing for their young." "This baby will need all the care that he can get to make it through his first Beringian winter." "Despite the cold, there is still food available." "The high winds stop the snow from building up and keep the grass exposed - a lifeline for all Beringia's grazers." "Away from the herd the dominant male mammoth is distracted from his usual routine." "Today he has a more urgent priority than food " "a younger challenger that wants to take his place." "This ritual clash of tusks will decide the future for them both." "The rival may be young and fit, the old bull has experience on his side." "This time experience wins." "The biting winter winds that clear the snow produce a windshield that would kill most mammals." "But musk oxen are made for this, cocooned in double layered coats." "But cold is not the only danger in this windswept land." "The herd reacts" "and runs for higher ground." "They huddle and turn to face the threat " "a Giant Short-Faced Bear." "Faced by a wall of horns, the bear moves on to sniff out a less daunty meal." "Occasional blizzards are another harsh reality of living in Beringia." "But the drifting snow may at least provide a hunter with some cover." "Saiga antelope can run at 40 miles an hour and so far this lion isn't close enough to cause too much alarm." "As long as they can keep it in their sights they are safe." "Eventually the sky clears and the blizzard stops." "Then ravens announce that the weather has taken its toll." "This old mammoth has succumbed to starvation and cold." "With its meat will help keep others warm." "The hunting lion homes in with another member of the pride." "They can soon see off the ravens." "But they're weary - a fresh carcass may have attracted other, more substantial competition." "One Giant Short-Faced Bear is more than a match for two lions." "But in this bitter climate lions can't afford to go without a meal for long." "A mammoth calf in its first winter is a tempting sight." "But mammoths are attentive mothers and they have the backup of their herd." "The calf is ringed by vigilant relatives." "The lions try to find a loophole." "The mammoths' matriarch, the oldest female, takes control and she has sixty years' experience of putting lions in their place." "In the bosom of its close knit family the calf is safe, from predators at least." "The lions will have to try elsewhere." "Could a bison be a more realistic prospect?" "The wind whips up again offering cover." "and the hunters focus on a target on the fringes of the herd." "Before long, the carcass freezes and becomes difficult to eat." "Abandoned, it is buried by the elements, preserved until the day it will emerge to tell the story of another Ice Age death." "Just one of many pieces of evidence which together have built up a picture of this remarkable world." "But now, another unforgiving winter's night falls on Beringia," "Land of the Mammoth." "Written  synchr. by m06166" "The southwest states of North America... a region of extremes... from the Colorado river and desert canyons to artificial landscapes that teem with life," "including one of the world's most vibrant cities." "This is Las Vegas a man-made oasis deep in the Nevada desert." "Only a century ago, this wonderland was sand and scrub." "Today it's one of the continent's fastest-growing cities." "All this depends on water pumped from the Colorado river 50 miles away." "Without this imported water, there would be no Vegas." "But during the last Ice Age, the Las Vegas Valley had a plentiful supply of water, and it was a magnet for all kinds of wildlife." "Just 13,000 years ago - not long in the vast time-scale of a continent this valley overflowed with lakes and ponds, fringed with the reed beds and swamps..." "All kinds of creatures would have been drawn to this natural refuge." "One group of new arrivals in this land of opportunity were people." "As the Ice Age ended and new pathways opened up across the continent, these hunters caught their first glimpse of the Canyon lands." "Imagine if we could travel back in time to see this wild new world and the strange and terrifying animals that lived here 13,000 years ago." "Using evidence left behind by these creatures, we will recreate life in the Ice Age Canyon lands." "It's taken millions of years to carve the red rock sculptures of the Canyon lands." "Today they spread across several states including Colorado, Arizona, Utah and Nevada." "These isolated, high plateaux are still home to some animals that were here at the end of the last Ice Age." "Today, the mountain lion is the largest predator that still patrols the canyons, living much as it did 13,000 years ago." "It's a tough existence." "Food is hard to come by, water too, and the desert climate swings from below zero overnight to nearly 40 degrees centigrade by day." "At least there's no shortage of shade." "A labyrinth of caves can offer shelter from the heat and cold and from the dangers of the night." "There was a time when even mountain lions couldn't sleep in safety." "These caves are haunted by the ghost of another carnivore that dwarfed the mountain lion," "probably the best known of all Ice Age hunters." "It killed with fangs like these, 20 centimetres long - the sabre-toothed cat." "But how exactly were these chilling weapons used?" "With its 300-kilo frame and short legs, the sabre-tooth was not that fast." "It probably ambushed prey, using its huge weight to pin it down before delivering a slashing bite to the neck." "Shock and loss of blood would quickly kill its victim." "And yet these lethal fangs must have caused problems for their owner too." "How do you eat with teeth this long?" "Even with a huge gape almost twice the span of any other cat the sabre-tooth could barely open its mouth wide enough to lift these massive canines clear of its lower jaw." "That would have made it very difficult to take a bite." "But it also had these special cheek teeth." "They suggest it ate through the sides of its mouth, slicing off manageable strips of flesh." "Even so, the sabre-tooth must have been forced to leave much of its meal for scavengers." "The mountain lion with its more modest canines can eat almost anything from mountain sheep to birds and even plants." "But today, like every other desert dweller, its main problem isn't food, it's water." "Away from the main rivers, waterholes are rare and soon evaporate in the heat and it may be months before they get refilled." "A real downpour may happen only once a year, but it can have a massive impact." "Storms don't just sustain life in the desert, they have helped to sculpt this spectacular landscape." "Rain runs off bare rock and gathers in the canyons, quickly escalating into flash floods that can carry away huge chunks of rock, constantly shaping and reshaping over millions of years" "creating a dreamscape of spires and gullies." "Over these millions of years, the larger rivers " "The Colorado, Green and San Juan - have carved out canyons up to one mile deep." "Water has sculpted the cliffs and gouged out innumerable caves;" "caves that store a wealth of clues from the Ice Age past." "One of the most remarkable cave sites was discovered on the Arizona-Utah border." "Here, the dry air preserved piles of evidence, not bones or teeth, but dung." "Football-sized dung balls, which dated right back to the Ice Age, carpeting the cave floor 10 metres deep." "But what colossal beast could have deposited them here?" "It was the largest of all Ice Age animals, a 10 ton relative of modern elephants, more than 4 metres tall." "The Columbian mammoth." "So, was this cave just a latrine, or were the mammoths here for other reasons - to escape bad weather, or the midday heat?" "Perhaps they used it as a night shelter, or came to visit salt licks, like some elephants do in Africa today." "No one really knows, but this prehistoric dung-pile offers plenty of other information about how Columbia mammoths lived." "It's mostly composed of grass, like elephant dung balls today." "To get enough food to sustain their huge bodies, mammoths had to graze for up to 20 hours a day consuming up to a quarter ton of grass." "When not eating, they were on the move, in search of fresh supplies." "They probably migrated through the river valleys and the bigger canyons, careful not to stray too far from water." "But the continent these mammoths travelled through looked very different from the one we know today." "During the Ice Age, much of North America was blanketed with massive ice sheets up to two miles thick." "And when the great thaw began, the changes in the north brought a new era to the desert." "For the first time, people were able to make the arduous journey south." "Today we can still map their route from stone tools left behind." "In just a few hundred years they spread down from the Great Plains, through the Canyon lands and all the way to Mexico." "They even took the mighty Colorado river and its apparently impenetrable canyons in their stride." "Including the Grand Canyon, carved out over millions of years, this is erosion on an epic scale " "280 miles long, up to 18 wide and more than one mile deep." "For people, crossing this forbidding landscape, must have been a superhuman feat." "But for other animals, it seems to be no barrier to travel." "Up here on the roof of Canyon lands are big horn sheep that seem to live almost off thin air, eking out a living from the meagre vegetation." "Specialist desert plants like cactus offer little nutrition... and their defensive spines make what goodness they do contain extremely difficult to reach." "But the hardy bighorn have evolved to get all they need from these plants, including moisture they need only visit standing water every few days." "And the females can still produce enough milk for their young." "But 13,000 years ago, another climber scaled these dizzy heights and left a clue to its identity high in a cave on the Grand Canyon walls." "A skull... with vegetarians' teeth..." "and short horns." "It belonged to a mountain goat, a common sight here in the Ice Age, with a shaggy coat to beat the biting winds." "Scenes like this would have been common back then, herds tip-toeing miraculously across suicidal slopes." "Now found only in the Rockies further north, they spend most of their time high up on the mountain slopes, but each spring they make their way down to the canyon bottom, where the river has exposed fresh earth and rock." "It's a crucial time of year the goats are shedding winter coats and losing vital minerals with the fur." "By nibbling these salt licks they can top up their supplies." "Even newborn kids must make the perilous descent to collect these crucial salts." "Other Ice Age creatures also roamed these precipitous cliffs." "In this Grand Canyon cave, scientists made a remarkable discovery recreated here." "Over 200 bones that, when put together, reveal a creature that's been dead for 13,000 years..." "From measuring these bones we know it was about as large as a black bear." "Its teeth have telltale grooves that are similar to the tree sloths still alive today in South America." "So, what strange beast died here?" "A Shasta ground sloth, once as common in the southwest as the bighorn are today." "Like the mammoths, it left more than bones and teeth for us to analyse..." "But the ground sloth's desiccated dung balls tell a different story to the mammoth dung." "They contain not just grass but many different plants, more than 100 species, representing almost every plant that once grew near the cave." "The Shasta ground sloth had a varied menu - prickly pear, saltbush and yucca;" "even the tough leaves of the Joshua tree." "The dung also reveals how Shasta ground sloths dined on different foods at different times of year." "Globe mallow and other desert flowers only bloom in spring but they were obviously gorged on when available." "What did the sloths use caves for?" "It's been suggested they were birthing dens, but they may simply have been sleeping quarters, a shelter from the cold desert night." "One recent study of the sloths' bone chemistry suggests that they were very sensitive to temperature - they may have come inside for warmth." "But a roof over their head was no guarantee of a good night's sleep." "Among the Shasta ground sloth bones was this strange skull resembling a mini sabre-tooth and from a creature just as bloodthirsty," "a vampire bat." "Vampires like this one are no longer found in North America, but once they lived in these caves sleeping by day, feeding at night on any warm blood that they could find." "The vampire bat uses tiny sabre teeth to nick its victim's flesh, then laps the blood by curling up its tongue into a kind of straw." "Anti-clotting agents in the bat's saliva keep the blood flowing until it's full." "Not all reminders of the history of Canyon lands are tucked away in caves." "The open strata of the cliffs reveal millions of years of geology." "Each layer represents a chapter in the story of the past all the way back to the age of the dinosaurs." "This dark band is slightly different - it's not rock, but debris from more recent times." "It's a rubbish dump, or midden, made of leftovers from thousands of small meals, all stuffed into the crevice and glued together with urine and droppings." "Who recycled all this debris - and why?" "It's the desert packrat, common all over the Canyon lands." "Generations of packrats contribute to the same middens over thousands of years, helping to form a tough protective shield around their rambling nests." "And they help scientists to look into the past." "Ingredients like prickly pear spines and juniper berries reveal just what vegetation grew across the Canyon lands" " and when." "Thanks to the packrats, we know that the bare rock of the high plateau was once green parkland with conifer trees and lush grassy meadows." "There were forests of juniper." "And the bare canyon walls were covered in a rich mosaic of trees and scrub." "Down on the drier plains Joshua trees flourished." "But the most symbolic desert plant today the nine-metre-tall saguaro cactus was rare 13,000 years ago." "Now there are spectacular saguaro forests but back then these broad valleys were carpeted with oaks, sagebrush and juniper." "Such dramatic changes tell us it was once much wetter and milder here than it is today." "Proof of this damper climate can be found and in perhaps the last place on earth you'd expect." "Death Valley;" "100 metres below sea level, this is the lowest point in the Western hemisphere." "It's also one of the hottest, driest places on earth, with daytime temperatures that soar to 50 degrees centigrade." "And it may not rain for years at a time." "Yet even in this furnace, there is life." "It exists in the many spring-fed pools that dot the valley floor." "These are desert pupfish and they manage to survive in water several times more salty than the sea, sometimes at temperatures of nearly 40 degrees." "Most pools support their own individual species and each pool is their entire world." "This is where they hatch, feed, breed and die." "But how did tiny fish end up living in the middle of the desert?" "The answer's all around in the vast salt flats that separate the pupfish pools." "This is the dry bed of a huge lake that existed here during the Ice Age." "When the climate warmed, the lake began to dry out, and the pupfish only managed to survive where springs continued to supply water." "Cut off from each other, pupfish then evolved into the many different species found today." "The existence of this prehistoric lake proves that the Canyon lands were once a wetter, greener place." "And that explains the different vegetation changes that we see recorded in the packrat middens." "The lake that filled Death Valley was huge." "Its waterways, marshes and reed beds would have been a magnet for all kinds of wildlife, and a pit-stop for migrating birds." "Vast flocks of cranes and geese flew in to winter here." "For several months, they'd gather strength before embarking on the long trip north to breed." "In this rich hunting ground, the cranes could eat their fill of fish, amphibians and water plants." "There were larger animals here as well." "The mild wet climate and abundant vegetation made the Canyon lands an ideal habitat for grazers, including some that would seem strangely out of place today." "Camels were very common and like Columbia mammoths and Shasta ground sloths they left plenty of dung pellet clues." "Dissecting their dung shows they had a varied diet from fine desert grasses to the toughest shrubs and trees." "We may think of bison as belonging to the open prairies further north, but back then they were equally at home grazing the valleys of the southwest." "They spent their whole lives following the rains in search of fresh grass." "This pattern of continuous migration ruled the lives of many creatures here including horses similar to modern zebra." "But 13,000 years ago, a new threat arrived in the canyon lands." "These first hunters had one big advantage:" "their prey had little or no experience of humans and was therefore easier to approach." "They were armed with flint spear points and tried and tested hunting strategies - working as a team, they were a match for any desert prey." "The hunters' success wasn't bad news for all desert creatures." "Their kills must have provided leftovers for scavengers like ravens." "Ravens still scan the Canyon lands for food and build their nests amid the pinnacles and towers." "Some of the ravens' ledges have been found to hold unique clues to the desert's past " "bone fragments from large animals like mountain goats," "wild asses" "and camels." "But how did they get all the way up here?" "Alongside is the answer, it's a huge beak from a giant bird " "an Ice Age condor." "Condors soared across the canyons on their huge three-metre wingspan, seeking carrion below." "Condors weren't the only scavengers 13,000 years ago, but they were big enough to overshadow many rivals including foxes." "With their immensely strong beaks, condors could rip through almost any carcass, tearing through the hide to reach the meat inside." "Smaller birds like cara caras waited for discarded scraps." "Fossils show that many other scavenging birds cruised the Ice Age canyons vultures, storks and eagles." "But if they survived by eating carrion, who was doing the killing?" "The fossils also show there was a front line of top predators:" "cheetah - the sprinter," "wolf - the pack hunter," "and lions - bigger and more powerful than any seen today." "All these hunters generated leftovers for scavengers to squabble." "But there was one more killer working these canyons, the most notorious of all Ice Age assassins." "Most of what we know about this hunter comes not from caves, but from a very different source - natural tar pits." "A single tar pit has been found with over 2,000 skeletons of sabre-toothed cats." "By studying the skeletons pulled from these pits, we can piece together how the flesh-and-blood cats lived and died." "These cats were hugely powerful, similar in size to African lions today, but heavier and densely muscled, weighing 300 kilos or more." "All this and then the terrifying canine teeth, which gave the cats their name." "A tiny bone found in the throat suggests the sabre-tooth could roar and so perhaps communicate with its neighbours." "Other bones tell other stories." "Many show some kind of injury, including broken teeth," "smashed legs and dislocated hips," "nothing unusual in animals that wrestled heavy prey." "But what is amazing is that these bones often show signs of healing meaning the cats lived on for months or years, even when permanently crippled." "But if they couldn't hunt, how did they stay alive?" "Some scientists believe that sabre-tooths were social animals and healthy members of the group supported weaker relatives." "But on the other hand, they may have simply used their terrifying looks to scare smaller hunters, wolves for example, away from their kills." "At the end of the last Ice Age, more sophisticated hunters started to arrive." "They were about to change the hierarchy of the Canyon lands forever." "Following the rivers, feeding on whatever big game crossed their path, their small bands quickly spread across the entire region." "From the moment these hunters set foot here, many Ice Age creatures started to decline and became destined for extinction." "But they left a trail of hidden clues throughout the caves and canyons of the desert, and each one helps us build a clearer picture of the past." "And if we can fit these fragments back together, we can bring a lost world back to life." "Combining all this evidence, we can now go back 13,000 years and recreate a day in the life of North America's Ice Age Canyon lands." "The sun breaks over the rim of the canyons and begins to warm the cool night air." "An early riser lumbers through the valley, and in the marshes along the river, roosting cranes begin to stir." "The winter's almost over, they will soon be leaving for the long flight north to breed." "Others have already stumbled upon breakfast." "It's a bison carcass but no meal comes easy." "It takes all the wolves' teamwork to extract it from the mud, and even then it's unlikely to feed the whole pack." "High above, a solitary hunter leaves her cliff-top den." "From here she can survey her vast range she hasn't eaten for a few days and she may have many miles to go to find a meal." "Signs of life, but out of even her league." "Columbia mammoths graze the high plateau." "Other members of the herd are still emerging from their night-time shelter in a large cave." "For these ten-tonne giants, it's a struggle to survive." "This canyon with its sparse vegetation won't support their massive appetites for long." "They'll have to move on in a few days' time." "The sabre-tooth starts to move down through the gullies to the flats around the river, where she knows there will be far more prey." "Another big cat has the same thing on its mind." "She too sets off towards the river," "but her path is blocked." "Even a mountain lion doesn't have the power or the weapons to compete with sabre-tooths." "Better to take the long way round." "With the sabre-tooth on her way down, the cliff-tops are a safer place." "By managing to scrape a living up here, bighorn sheep avoid the dangers of the open valley floor." "But even they need water every now and then, and have to scramble down to reach the river." "Some members of the mammoth herd come down to drink before they start the daily grazing marathon." "Once in the meadows, they mingle with horses and wild asses, camels and bison," "all drawn by the spring flush of new grasses, flowering plants and sprouting bushes." "The Shasta ground sloth waits until the morning chill has gone before he ventures out." "He comes back to his cave each evening, but by day he wanders miles around the Canyon lands, dining on anything that takes his fancy." "The ground sloth's lucky - he can tackle tougher plants than mammoths." "In fact, he can eat almost anything." "The sabre-tooth's already hot on his trail, but so far the sloth is preoccupied with breakfast." "Camels browse the trees and bushes." "Like the sloth, they're tempting game for any hunter." "After taking shelter in the canyon overnight, the camels too converge on the river and must run the risk of crossing open ground." "Their expedition quickly draws the sabre-tooth's attention." "They're softer targets than the faster, more elusive prey." "Once at the river's edge, the camels are at their most vulnerable, hemmed in between the cliff-sides and the Colorado river." "It will take the camels only minutes to refill their 100 litre tanks, but they've been side-tracked by lush browsing on the riverbank just long enough to let the cat catch up." "The sabre-tooth's not built for long pursuits, but if she can creep close enough she'll use a burst of speed to launch an ambush." "One hit... and one bite..." "is all it takes." "The camel is as good as dead." "The cat withdraws out of harm's way leaving blood loss and shock to do the rest." "But as the sabre-tooth moves in to claim her kill, she's not alone." "A second cat emerges from the bushes." "This one has a badly damaged leg, the legacy of ambushing a bison, and she couldn't possibly compete for food." "But will the hunter tolerate another cat at her kill?" "These two are not rivals." "They're blood relatives." "The hunter shares her food to help the injured cat survive." "But even for the fittest sabre-tooths, new competition means life is about to get a lot tougher." "While human hunters quickly find their feet here in the southwest and increase their numbers, sabre-tooths - like many other giants of the Ice Age - are now living on borrowed time." "Soon only the ghosts of these great cats will haunt the valleys and plateaux of the Canyon lands." "This is Florida, a taste of the tropical," "one of the world's most popular holiday destinations." "Here, mankind's unquenchable desire to explore and colonise reaches astronomical proportions." "And yet we are relative newcomers here." "While other creatures roamed this part of North America for hundreds of millennia, we only arrived at the end of the last great Ice Age," "13,000 years ago." "For most of its existence," "North America remained untouched by humans, its dramatic landscapes and wildlife undisturbed." "Then, sometime around 13,000 years ago, just as the ice started to relax its grip, hunters from the north set foot in Florida for the first time." "Imagine if we could go back and join them as they explore this unknown land, encountering strange animals not seen before by human eyes." "By piecing together the evidence these creatures left behind, we can build a picture of this sub tropical corner of the continent as it was 13,000 years ago." "While most of North America was still in the grip of the big freeze," "Florida was an Ice Age oasis." "Florida is aptly named the Sunshine State." "With an average of 8 hours of sun a day, it seems a world away from any ice age." "Even 13,000 years ago, the massive ice sheets were hundreds of miles away to the north." "So what was it like back then?" "To investigate Florida's Ice Age past, one of the best places to look is underground" "and underwater." "Just below the surface lies a very strange world." "Millions of years of water action has dissolved the limestone rock, forming a system of flooded caves and tunnels." "This vast underground network runs for thousands of miles." "Much of Florida is basically a big rock honeycomb." "In places the water is forced to the surface, forming springs." "Florida has one of the largest concentrations of springs in the world." "Filtered through sand and rock, the water is crystal clear." "And welling up from deep within the earth, it is a constant 22 degrees centigrade." "This creates steaming oases, and a profusion of life." "Today these warm springs are a refuge for one of Florida's most tropical inhabitants." "The West Indian manatee wasn't present during the last Ice Age, but returned here as the waters warmed up." "Even now it is only found around this sub tropical tip of the continent." "But these springs aren't just a haven for modern day wildlife." "They've also yielded many secrets of the distant past." "When these pools were first explored, they would have looked like this:" "strewn with astonishing fossil remains from Ice Age beasts." "Florida has one of the richest fossil records of the Ice Age anywhere on Earth." "So what kind of creatures did such bones and skulls belong to, and how did these springs become their graveyards?" "Many of the fossils are from animals that you can still see today." "Indeed we'd recognise the vast majority of Florida's Ice Age wildlife." "Nevertheless, the most spectacular Ice Age beasts did become extinct." "And remarkably some of them share a common ancestor with modern manatees." "At first sight manatees might look like seals or dolphins, but in fact some of their closest relatives live on land." "These toenails are the giveaway remarkably similar to those of elephants." "13,000 years ago, two other members of the elephant family roamed this land." "The manatees that swim in Florida's springs today are living relatives of Ice Age mammoths and mastodons." "Some of the bones found in these springs are easy to identify, but scattered in among them are some more obscure remains." "What kind of animal could this belong to?" "These rosettes are bony scales, or 'scutes', similar to those that cover some reptiles today." "But this is only one piece of the jigsaw." "Imagine what the creature would have looked like when all these pieces were fitted together." "The scutes - around 2,000 of them once formed the shell of a huge animal called a glyptodont." "With its heavyweight exterior the glyptodont looks like a reptile, like the alligator, which has been around for millions of years, long before the last Ice Age." "But the glyptodont wasn't a reptile." "So what was it?" "There is a relative of the glyptodont that's still alive today." "It's the armadillo, and it's a mammal - the only mammal with this kind of armour in the whole of North America." "It may give us some idea of how an Ice Age glyptodont might have looked when alive." "Armadillos have poor eyesight, and rely mostly on their sense of smell." "Much of their time is spent nose to the ground in search of food." "Like the glyptodont, they're covered in a layer of bony scutes." "But the armadillo's body armour is surprisingly thin and flexible and doesn't slow its owner down." "So what about the glyptodont?" "The glyptodont's scute casing was up to 5 centimetres thick, and fused into a solid shell." "The shell alone was extremely heavy and the entire animal probably weighed as much as a small car." "It had extremely sturdy legs and five toes on each foot to spread its massive weight." "The heavy tail probably acted as a counter balance." "So the glyptodont wasn't built for speed, but inside all this body armour, you'd imagine it was well protected." "But one fossil skull tells a different story." "It suggests the glyptodont's defences weren't impenetrable." "These holes are the unmistakable hallmark of a violent death." "Their shape suggests that they were made by the teeth of a big cat, but which one?" "Today there's only one large cat in the region - the Florida panther." "Though similar to the cougar of the western states, it's now much rarer." "But it was around during the Ice Age, so could it have killed the glyptodont?" "Although it could easily manage a deer, the Florida panther was probably too small to tackle such a giant." "But it wasn't the only big cat around 13,000 years ago." "There was also the mighty American lion," "powerful enough to kill a glyptodont." "The scimitar-toothed cat, known to attack young mammoths, was also big and strong enough." "And then there was the most infamous cat of all - the sabre-tooth." "Like the scimitar, it saved its awesome fangs for slashing soft flesh." "It would have been unlikely to risk breaking them on bony armour." "But the warm climate of Ice Age Florida made it a sanctuary for another killer cat." "Still South America's top predator, the jaguar is capable of taking prey much larger than itself." "Weight for weight, it's probably the most powerful cat alive today." "But most significant of all, the jaguar has a tell-tale trademark." "Instead of going for the neck or snout like most cats do, it kills with a crushing bite through the skull into the brain." "This makes the jaguar prime suspect in this case." "Even the glyptodont's defences had a fatal flaw." "13,000 years ago another, very different kind of hunter reached this warm corner of the continent." "Florida's springs have produced an unparalleled record of these first people, examples of their craftsmanship and hunting expertise, including razor sharp flint spear points." "The area was rich in flint for making weapons, and in animals to hunt." "And with the milder climate, these people probably had an easier life than their contemporaries further north." "Small clues to their arrival have survived undamaged over 13,000 years." "Spear points, fishhooks and other glimpses of their daily life, showing the versatility of these first inhabitants of the sunshine state." "They hunted a wide range of Ice Age animals, and Florida possesses a unique record of one such encounter." "The skull of an extinct bison, restored here, was discovered in one of the rivers." "Planted deep in the top of the skull was a flint spear-point." "But how did one man and a spear produce the huge force behind this blow?" "The answer lies with small bits of ivory, like this." "They were once part of an 'atlatal', or spear thrower." "An atlatal acts as a sort of catapult, magnifying the strength of a hunter's throw, allowing him to launch a spear up to 200 metres" "with enough power to drive the point through a bison's skull." "It's this kind of sophisticated technology that helped these early North Americans to spread throughout the entire continent." "But what else did they find once they reached Florida?" "Florida's Ice Age wildlife was remarkably rich and diverse." "There were many familiar animals normally found further north, but also creatures unique to the tropics." "The result was a mixture of species unlike anything we see today and an abundant food source for the human immigrants." "So what produced Ice Age Florida's wealth of wildlife?" "Part of the answer comes from the ice itself." "At the peak of the last Ice Age, massive glaciers up to 2 miles thick covered over half the North American continent." "The ice destroyed the habitat over which it lay, but it also had a profound impact on regions far away." "It created a domino effect that rippled down the continent." "The cold-climate conifer forests of the north displaced broadleaved woodlands." "Plants and animals were gradually pushed south to find a warmer climate." "Florida became a refuge from the cold." "Down here is where the Ice Age north met the sub-tropical south." "Today in a cool, wooded part of the sunshine state, you can still see some of these northern refugees." "The valleys along the Apalachicola River are home to many species that were forced here in the Ice Age and now remain far away from their main populations further north." "Like the copperhead snake" "and an astonishing variety of amphibians." "During the Ice Age," "Florida was crucial to the survival of many such mild weather species." "They couldn't have withstood the cold up north, and without this refuge they would simply have become extinct." "Another leftover, but one that arrived from the opposite direction." "This is the Virginia opossum, a tree dweller found throughout many of the southern states." "It's the only North American marsupial - the young are born premature and nurtured in the mother's pouch." "And its only close relatives today are found in Central and South America." "The opossum is a rare survivor from a South American invasion." "In the Ice Age there were many other species that had travelled north to Florida including a giant." "This spectacular claw is 40 centimetres long." "And it belonged to a creature whose fossil remains have been found throughout Florida." "It's the claw from a giant ground sloth." "And it really was a giant," "6 metres long and weighing up to 4 tons, it rivalled the mammoths in size." "Although the giant ground sloth is now extinct, like the opossum, it has family ties in South America." "The family resemblance is easy to see." "These menacing claws are used as grappling hooks, not weapons." "They belong to the tree sloth, a peaceful vegetarian that spends its time eating leaves." "It seems a far cry from our vision of an Ice Age beast." "It's likely giant ground sloths used their claws in a similar way to hook branches and pull them within reach." "Like tree sloths, they were vegetarians, and probably not fussy about what they ate, chewing their way through leaves, fruit, twigs and all." "The big difference between the two is their size." "Giant ground sloths were 500 times bigger than their modern relatives and standing upright on their back legs, they towered as tall as a giraffe." "So far we have pieced together something of the people who first explored the south east of the continent, and the wildlife they must have encountered and hunted." "But what about the climate and the landscape they all lived in?" "Florida is tropical today but how warm was it 13,000 years ago?" "This is Little Salt Spring in central Florida, the source of one of the most unlikely clues to the climate of the past." "Brought up from a ledge more than 20 metres below the surface, was the fossilised shell of a tortoise, a giant tortoise, much like this one." "Giant tortoises are now only found basking in the heat of a few islands along the equator." "They can grow more than 2 metres long and weigh as much as 3 men." "But the giant tortoises of Ice Age North America were even larger." "Florida does have tortoises today, but on a much smaller scale." "This is the gopher tortoise." "Tortoises are cold-blooded animals - they rely on external temperature to keep themselves warm." "Although Florida is plenty warm enough for much of the year, during the winter months it can get cold." "So to survive the winter gopher tortoises must burrow and hibernate underground." "The colder it gets, the deeper into their burrow they go." "Giant tortoises, however, can't burrow and they sleep above ground." "They need relatively warm temperatures all year round." "The fact they were in Florida during the Ice Age means that, paradoxically, the climate must have been more stable and even milder than it is today." "So we know something of the climate, but what about the vegetation and the landscape?" "How did that look 13,000 years ago?" "Today Florida is one of the wettest parts of the continent, especially the vast swampy area known as the everglades." "Flooded grassland stretches as far as the eye can see." "But despite their name, the mighty everglades did not exist during the Ice Age." "So what did prehistoric Florida look like?" "There's one place in Northern Florida that has revealed more Ice Age secrets than almost anywhere else " "the dark, slow moving waters of the Aucilla River." "Here, ideal conditions for fossilisation created a hidden store of Ice Age evidence." "Unlike in the crystal clear spring waters, these clues were never on view for all to see." "But the Aucilla has now been studied intensively for more than 20 years." "Along some stretches of the riverbed were massive bones, recreated here, perfectly preserved for more than 13,000 years." "One of the most significant discoveries was the huge skull of an American mastodon." "Mastodons, close relatives of mammoths, were widespread all over North America during the Ice Age." "They grew over 3 metres tall - the size of African elephants today." "We know a lot about the mastodons, especially their diet, thanks to the preserved dung they left behind." "Some of this Ice Age dung was found beneath the skull in the Aucilla." "The dung contained plant remains that tell us what the mastodon was browsing on" "13,000 years ago or more." "A mixture of trees and grasses." "This suggests that Ice Age Florida was drier than it is today a mix of woodlands and savannah, rather than swamps." "And mastodon teeth found in the Aucilla held a more important revelation." "The enamel contains chemical signatures of the local soil, passed via the plants the mastodons ate." "But some of the chemicals found in the Aucilla teeth could only have come from soils hundreds of miles further north." "The inescapable conclusion is that these mastodons migrated making a round trip of more than 400 miles every year." "And since their dung also contains remains of summer fruits from the Aucilla region, they must have travelled north for the winter." "The question is why?" "Why leave a place, which, as we have seen, was abundant with food, and a refuge from the cold?" "And why go north for the winter, when most migrants move south?" "Perhaps the present climate can provide a clue." "Florida has a peculiar seasonal quirk." "Although the winter months are cooler, they are also drier - much drier." "Between October and February there's almost no rainfall at all." "Could it be that drastic water shortage was the reason for the mastodons' epic migrations?" "Another big piece of this puzzle lies far out to sea." "This is the ocean floor," "but this isn't rock sprouting out of the bottom, it's wood." "It's the remains of prehistoric tree stumps, some dated at more than 12,000 years old." "This sunken forest is unmistakable evidence that what is now seabed was once dry ground." "And what is now Florida's coastline was once many miles inland." "But why?" "To answer that we have to go back to the mighty Ice Age glaciers that covered almost half the continent." "These glaciers contained immeasurable amounts of ice." "So much water was locked up in this ice that it lowered sea levels by over 70 metres." "The south east coastal shelf was exposed and Florida doubled in size." "The Everglades were dry land." "This triggered other dramatic changes." "As sea levels dropped, so did the inland water tables." "Florida's fresh water drained away through the porous limestone rock." "Pools dried up and springs diminished." "Florida was on the brink of drought, and animals would have had to travel to find food and water." "So each year mastodons would have migrated to the wetter regions." "But in a few key places, water was still pushed up from underground as a spring " "a vital oasis where wildlife would have converged from many miles around." "Many animals would have fed on the surrounding vegetation and others come here to drink." "And predators would have lain in ambush for the unwary." "It's no wonder that so many fossil bones have been found on the bottom of these springs - clues that can open up a window on the Ice Age past." "Bringing this evidence together, we can create a living picture of this region as it was then." "We can now go back 13,000 years and see what a day around one of Florida's springs might have been like." "Dawn on the southeast tip of Ice Age North America..." "On the banks of a spring-fed pool, the early grazers stir." "Today there is a group of larger visitors here too." "A herd of mastodons, led by the matriarch, have just returned from their annual migration, hundreds of miles to the north." "Now the winter drought is over and the spring water has been topped up by recent rains." "Another group has also set up camp nearby." "Hunters, descendants of the first human settlers that entered the continent in the far north." "Compared to the harsh conditions their ancestors faced, this place is paradise." "Targets for the hunters' spears are plentiful." "Around the spring, lush vegetation attracts the giant ground sloth, too." "Both mastodons and sloths are browsers, but the mastodons roam far and wide to find the kind of plants they need." "The giant ground sloth isn't built to travel far, but it makes up for that by having the reach of a giraffe." "Its huge claws may also be used for self-defence, although even the most powerful predator would think twice before tackling so large a prey." "In any case, this female jaguar is little threat right now." "Once she's quenched her thirst she'll find a shady place to doze in the heat of the day." "Meanwhile the ground sloth, like the mastodons, must eat most of the day to fuel its huge bulk." "This may be the Ice Age, but by midday temperatures soar drawing another predator to the spring to drink " "the notorious sabre-toothed cat." "Most creatures give the sabre-tooth a wide berth, but this skunk seems unconcerned." "The sabre-tooth may be the ultimate Ice Age predator but the skunk is feared, too because of its unique system of self-defence." "These stripes serve to warn off most attackers, but perhaps the sabre-tooth has yet to learn exactly what they mean." "Stamping his feet, the skunk issues a final warning, but this big cat is still curious and now the skunk has had enough." "The dreaded sabre-tooth, killer of mastodons and other Ice Age giants, is defeated by a small but very smelly skunk." "In the heat of the day, hunters can afford to slow down and rest in the shade." "It's one of the advantages of a high protein diet." "Llamas originated here in North America and are regular visitors to the spring." "The strange looking tapir is common too." "And there's another animal that is even more bizarre - a glyptodont." "This lumbering vegetarian is no threat to the llamas, but it does arouse their curiosity." "The glyptodont is short-sighted and wary, but it has little to fear from llamas." "They're easily warned off and soon head back towards the spring." "But as the day cools down, another scent is in the air alerting the tapir's ultra-sensitive nose to danger." "The llamas pick up the signals too." "It's the jaguar, back on the prowl." "Though very powerful, she's not a sprinter and she needs to get close to her prey before she strikes." "This time she's run too soon and it's a fruitless chase." "Then her attention is diverted to a slower-moving target." "Slow but not defenceless, she backs off and tries a different approach." "There's obviously a meal in there, but how to get to it?" "She homes in on the head and bites straight through the skull." "The glyptodont is dead, but the jaguar still goes hungry." "Unable to crack her victim's tough armour, all she manages to walk away with is a bony scute." "The jaguar will vanish from North America, and glyptodonts, like many Ice Age beasts, become extinct." "But at the bottom of a spring, one tiny fragment of an Ice Age giant will remain undisturbed for 13,000 years, while above it the landscape of Florida will change forever." "Seattle on the west coast of North America." "One of the world's most high tech cities, it draws thousands of workers and visitors every day." "But how did the very first travellers get here and what would they have seen?" "When people first set foot in the Northwest they were to encounter some of the most impressive beasts ever seen on the continent." "Using clues from the present to revisit the past, we reconstruct life in the far Northwest at the end of the Ice Age and discover how people and animals came face to face at the edge of the ice." "As we shall see from evidence left behind, people were present in North America 13,000 years ago." "But how did they travel here and where did they come from?" "The answers may lie in the northwest region of the continent." "In this programme we uncover clues not only to a journey taken by people, but to a wilderness that they became part of, a wilderness that no longer exists." "In doing so we get a glimpse of the life and death encounters in this corner of the continent at the end of the Ice Age." "And we reveal how the Northwest offered people a route into North America, which until recently was thought impossible." "It happened just as the huge ice sheets that covered most of the continent were breaking up, sometimes with a devastating impact on the people and animals living in the shadow of the ice." "Today we can examine the evidence of that dramatic era using it to recreate the landscape and the wildlife of the distant past." "Bones and fossils can also tell us about the lives of the first people." "To get a picture of how much this region of the continent has changed since the end of the Ice Age we must look at the present day landscape of the Northwest." "Today this area is home to some of the world's most spectacular temperate rainforest ranging 2,000 miles from modern day Seattle up into Alaska." "The Pacific Northwest thrives on water more than three metres of rain falls every year to swell the forest rivers." "Mist and fog are as important to these coastal forests as rain." "All this moisture helps produce some of the planet's tallest trees towering 100 metres above the ground." "These ancient forests are one of the few true wildernesses left in North America and are home to creatures that have come to symbolise the wild." "But these dense forests aren't as old as you might think." "They certainly weren't here at the end of the Ice Age 13,000 years ago." "The trees were sparser then and mixed with open grassland." "So were the animals that lived here different too?" "This small town in central Oregon has proved to be a window on the past." "Some of the region's most important fossil evidence has been unearthed beneath its streets." "Bones like these help to paint a picture of the living creatures they belonged to." "This was the largest grazer in the Northwest, standing 4 metres at the shoulder - the Columbian mammoth." "And its biggest enemy - the predatory scimitar toothed cat." "As the great melt began, grazers and meat-eaters alike were faced with massive change." "Vast areas of land were transformed, gradually reviving after hundreds of thousands of years buried under the ice." "The glaciers we still see today in the North West are mere remnants of immense ice blankets that once dominated North America." "Their sheer scale is still impressive." "Some are several miles wide, hundreds of metres deep." "But now the glaciers are in retreat, as they have been for over 13,000 years." "Remarkably, some of the icebergs set free by the melt consist of water frozen tens of thousands of years ago." "These floating fragments now provide a temporary resting place for harbour seals and their pups." "Imagine these glaciers at their peak." "It's thought they covered half the continent in layers almost 2 miles deep." "When the planet starting warming up, the ice sheets melted, usually over thousands of years." "But this process wasn't always slow and gradual." "This scarred landscape was created by one of the biggest flash floods the world has ever seen." "The waters from that flood scoured deep into the bedrock, and sculpted canyons such as these in Washington State." "These cliffs are known as Dry Falls." "They are geological ghosts, reminders of the great flood that once swept across this region." "Around 12,000 years ago a giant ice dam in a lake 180 miles long collapsed under the weight of water." "A huge wave up to 600 metres high raced across the land at speeds of more than 60 miles an hour." "This floodwater cut deep into the landscape, forming a giant waterfall several miles wide and more than twice the height of Niagara Falls." "The roar of the advancing tidal wave would have been heard by animals hundreds of miles away as much as half an hour before it reached them." "Two days later the lake was empty and the torrent started to subside, but by then millions of animals had died." "Some of the fossils found beneath the streets of Woodburn show it may have been hit by these floods." "And there may have been people living here at that time." "A strand of human hair discovered deep underground has been dated at around 12,000 years old." "While many stone tools from the ice age have been found, evidence such as hair is very rare." "The dating of the Woodburn hair is controversial but if correct, it represents one of the oldest human relics on the continent." "But is there other evidence to back it up?" "Another crucial hint that people did exist here as the Ice Age ended was discovered to the north of Woodburn on the Olympic Peninsula." "A two and a half metre long tusk was found and led to the unearthing of a giant skeleton, recreated here." "Just the left hand side remained, but it was enough to identify one of the most impressive creatures of the Ice Age " "a mastodon." "Mastodons, like mammoths, disappeared soon after the Ice Age ended, and this skeleton revealed one possible reason why." "Between the ribs of this large male was found what seems to be a spear point, which implies this mastodon had encountered human hunters." "A closer look reveals the rib bone healed around the injury, showing that even if the mastodon had been attacked, he survived." "Mastodons were distant relatives of woolly mammoths, but slightly smaller at around 3 metres." "It's thought that while the mammoths grazed the open grasslands, mastodons favoured patchy forests and swamps." "They moved in small herds, browsing on large shrubs and trees." "We know what they ate partly from the fossil teeth they left behind." "Their teeth had high, ridged cusps, thought to be used for grinding tough material like branches." "And plant remains found near the teeth suggest the mastodons preferred to dine on pines and other conifers, using their trunks to pull off branches, much like modern elephants." "Today, the largest browsers on the continent are moose." "Moose weren't present in the Northwest during the last Ice Age, but can their feeding habits give us an idea of how the mastodons lived then?" "Moose spend most of their time browsing on deciduous trees." "But at certain times of year they try something a little different." "It seems that water plants in lakes and ponds provide essential nutrients that moose can't get from trees." "Mastodon remains are often found preserved in ancient bogs and swamps suggesting they too may have varied their tree diet with seasonal water plants." "We know that mastodons and moose did not overlap in the Northwest." "But if the large male found on the Olympic peninsula was victim of a spear attack, it seems that mastodons and people did." "But how did human hunters reach this area to start with?" "To retrace their steps we need to travel further north to the islands off the coast of South East Alaska." "This is Admiralty Island, famous for its brown bears." "Until recently it was assumed that 13,000 years ago it was covered in ice, just like most of the mainland." "But a recent study of Admiralty's bears reveals they are genetically different to those on the Alaskan mainland." "This suggests they must have been cut off here on the island for tens of thousands of years." "So could it be that Admiralty island was an ice-free zone during the Ice Age?" "The genetic evidence suggests it was." "Bears are usually solitary creatures, but in summer they are drawn together by the need for food." "Mothers with spring born cubs begin to congregate around the coastal rivers, as they would have done during the Ice Age." "They're here to catch migrating salmon on their way upstream." "In these tidal shallows it's like fishing in a barrel." "For the cubs, it's time to look and learn as mother shows them how it's done." "But sharpening those predatory instincts takes a lot of practice." "The study of the Admiralty bears suggests these coastal islands may have been like stepping stones, allowing animals to move around during the Ice Age, island hopping down the coast before arriving on the mainland." "And this idea is backed up by other evidence nearby." "This weathered limestone on Prince of Wales Island is riddled with caves." "And one cave in particular, recreated here, turned out to be a treasure trove of fossils." "Some of the bones found belonged to a large brown bear, dating from the peak of the last Ice Age." "There were there other animals apart from bears." "In the same cave on Prince of Wales island, a smaller skeleton was found." "An Ice Age Arctic fox which would have used the cave to stash its food." "There were the scattered bones of seabirds too, probably leftovers from the fox's meals." "Foxes need open ground to breed and it seems that Prince of Wales island, like Admiralty, provided this during the Ice Age." "We now know some regions of the northwest coast offered an ice-free sanctuary throughout the Ice Age." "So could people have been travelling between these islands too?" "The evidence suggests they were." "The Prince of Wales Island cave also held the fossilised remains of at least one human," "including a complete lower jaw." "The position of the wisdom teeth suggests the jawbone came from a man in his early twenties." "But his teeth were deeply pitted for his youthful age." "What could have caused this damage?" "Again, the coastline seems to hold the answer." "There is a saying in Alaska that the tide lays the dinner table twice every day." "With each low tide the newly exposed rocks present a seafood platter." "And it's available all year round." "So shellfish would have been an easy and accessible source of protein for these early North Americans." "There's even evidence that they used bags and baskets to collect food along the coast." "But shellfish, while nutritious, can be very gritty, which may help explain the deep pits in the fossil teeth." "Chemical analysis of other bones seems to confirm that what the man ate did indeed come mostly from the sea." "And there are other clues relating to his death." "One of his hips was marked with scratches." "Where did these come from?" "Perhaps a scavenger that found the young man's body." "Or were they made while he was still alive?" "Humans weren't the only animals that used caves for shelter." "The attacker may have been a bear, quite common in these caves during the Ice Age." "Although the young man's bones date back just to the end of the last Ice Age, scientists think Prince of Wales island was probably habitable even earlier, when the mainland was still deep frozen." "These islanders were far removed from the cliche of primitive stone age man." "Able to sew and weave, they made different clothes for different seasons and even decorated themselves with jewellery." "But how did they first arrive here on these offshore islands?" "Their skills must have included making and navigating boats." "Exactly where they sailed from isn't certain, but they may have come from Northeast Asia, island hopping across the Pacific until they hit the coast of North America." "At first they probably relied more on the sea's resources than the land." "They may even have traded goods between the islands." "But they didn't stay islanders forever." "As the mainland glaciers receded, a brand new land began to open up to them." "They may have travelled partly with the seasons, guided by the best time and places for fishing." "This spectacle would have been a golden opportunity." "Every year in early spring vast schools of herring gather off the coast to spawn, attracting sea lions from miles around." "These same events took place here 13,000 years ago and could not have gone unnoticed by the bands of seafaring hunters." "While the sea lions hunted herring, people no doubt hunted both." "As herring near the time of spawning they draw closer to the shore." "Here they begin releasing eggs and sperm into the tidal waters." "The sheer scale of this reproductive frenzy can turn miles of coastline milky white, just as it did during the Ice Age." "As the Ice Age glaciers melted and the rivers opened up, another kind of fish began to head inland." "Without the barriers of ice, migrating salmon penetrated upstream deep into the continent." "These freshly flowing rivers and the fish they carried lured people further inland too." "In small groups they branched out to continue their passage into the new world." "They were continuing a journey that had started with their ancestors on the other side of the Pacific Ocean somewhere in Asia." "These inroads brought their first contact with the large beasts of the continent including the Olympic Peninsula mastodon." "Although it seems to have survived its first attack by human hunters, there is evidence that in the end people dined on its meat." "Marks on its bones appear to show that it was butchered after death." "A large bull mastodon was quite a prize, alive or dead." "But if the hunters didn't actually kill the mastodon, what did?" "Another cave discovery reconstructed here has shed light on an Ice Age predator that may have been the biggest enemy of mastodons and mammoths " "the scimitar-toothed cat." "Like its notorious relative, the sabre-tooth, the scimitar possessed long lethal canines, used to slash and kill its victims." "The inside of this cave is testament to its success." "More than 400 remains of baby mammoth and mastodon were found alongside the scimitar skeleton." "The fearsome canines had serrated edges and we can learn more about the scimitar's hunting techniques from its skull." "Like a modern cheetah, it had larger nasal passages than most cats." "In the cheetah these deliver extra oxygen for short fast sprints." "A good grip is essential to the cheetah in a chase, something the scimitar cat also possessed." "And like tigers, scimitars had powerful jaws helping them to dismantle the bodies of their prey." "These crushing jaws are also used to carry large kills back to dens." "Like most cats, the scimitar was probably a solitary hunter, and like generations of earlier occupants, it would have used this cave to store fresh carcasses." "This may also have been a birthing den, a safe place for the scimitar to leave its young while hunting." "In the quiet of its hideaway, the scimitar could rest after a kill and this one, perhaps old or injured, seems to have come home to die." "Scimitar cats became extinct around the same time as the mastodons and mammoths - another hint that they depended on the elephant-like creatures for their food." "But the evidence suggests these cats normally attacked young animals, making it unlikely that a scimitar killed the Olympic Peninsula mastodon." "So if it wasn't killed by human hunters or by a scimitar, perhaps this mastodon was not the victim of a predator at all." "Another theory comes from the bones themselves." "The cheek teeth used for browsing were extremely worn almost down to the gum - a sign of heavy use over many years." "But this wear and tear may also have resulted from eating food outside the mastodon's normal diet." "Bones of grazers such as bison lay close to its skeleton, implying this was open grassland at the time." "Caribou were also found nearby - creatures that also favour open spaces." "Today they live mainly on the tundra of the far north." "The presence of these other animals suggests the mastodon was not surrounded by its normal forest habitat." "Instead, this area was treeless grassland grazed by caribou and bison." "Unlike a mammoth, mastodon teeth weren't designed for eating grass, which contains large amounts of erosive silica." "The silica may have destroyed this mastodon's teeth early and contributed to its death." "In the end it seems this bull was probably a victim of a bad diet and old age." "Now we've seen the evidence, we're equipped to travel back in time, back to the end of the last Ice Age 13,000 years ago to experience a day in the life of the Northwest, as witnessed by the first people." "This lake is a lifesaver for these mastodons." "It provides more than water." "As there are few trees to browse on, water plants are a valuable source of nutrition." "For some of these mastodons it's a temporary visit." "They will move on in search of open forests once they are well fed." "The search for food and water has brought a new arrival." "These people have used rivers to move inland from the coast." "This is the natural home of caribou and woolly mammoth - both tempting prey for these people." "They hunt smaller creatures too and use their fur for clothing to keep out the wind and cold." "These people bring many other skills and are highly adaptable." "But to most of the animals that live here, they are a new, unknown quantity." "As the ice begins to lose its grip, the land is in a state of flux and many different creatures mix." "The open grassy plains are favoured by mammoth herds." "But these mammoths have to share the lake with mastodons, their smaller cousins." "While some of these mastodons are migrants, travelling onwards searching for fresh forests to browse, for this old bull, at nearly 50 years of age, this is the last stop." "Weary and arthritic, he bears the scars of his long, arduous life." "The scimitar, a lion-sized cat, is never far away from mastodons and mammoths." "Although slighter in build than its relative the sabre-tooth, the scimitar is the biggest predator of North America's elephants." "Right now, though, opportunities are rare - even a scimitar cannot attack an adult in its prime." "But older animals, such as this feeble bull, could be potential targets." "A long and eventful life is drawing to a close." "Bull mastodons live most of their lives alone, but in their final hours they seem to attract company." "For a scimitar a mastodon near death is a temptation worth pursuing." "But mastodons, like many elephants, are fiercely protective of the dying." "For the scimitar, the mastodon's slow death becomes a waiting game." "The mastodon has died in peace, and now the scimitar has got his meal - a feast that soon attracts further attention." "There's far more meat than this cat needs, but it's still loathe to let in the others." "Against another cat, it holds its ground, but other hunters are arriving at the lake." "The scimitar is doomed to lose its meal and faces a potentially dangerous situation." "This is the first time this scimitar has encountered people." "On this occasion the cat gives way to these formidable new hunters." "Humans, like other animals, will find food where they can and scavenging is one way to survive." "It's a time consuming task but these people are well equipped to butcher as much as they need." "The mastodon carcass could provide food for a later date." "It's not uncommon for meat from large kills to be prepared and saved." "In the end they abandon what's left of the mastodon, and the carcass sinks into the boggy lake." "With it lies the story of its Ice Age life and death, remaining buried until its discovery 13,000 years later in the Northwest of modern day America." "Daybreak on North America's great plains." "Denver International Airport is coming to life and about to receive the first arrivals of the day." "By midnight, more than fifteen hundred aircraft will have touched down here, delivering tens of thousands of people to this modern metropolis." "But when did people first come to the plains?" "It's not so long ago in the life story of the continent just 13,000 years since this was virgin territory." "And back then different giants cruised the landscape." "Imagine if we could travel back in time and see these plains as they were then, emerging from the grip of the last great Ice Age " "an area of pristine wilderness, stretching for one and a half million square miles, untouched by man and brimming with extraordinary animals." "But 13,000 years ago, an even more extraordinary animal arrived." "What if we could follow in the footsteps of these first hunters, as they entered the unknown and staked their claim to these vast spaces?" "What would this wild new world have looked like through their eyes?" "And what strange creatures would they have encountered here on the American Serengeti?" "As North America emerged from the grip of the last Ice Age, the door was opened to outsiders for the very first time." "As these early immigrants pushed their way south, they found themselves in a land of unimaginable opportunity, overflowing with game animals," "animals with no experience of humans or their weapons." "The arrival of these hunters coincided with a time of great change on the plains." "Within the next few hundred years, many Ice Age animals vanished forever." "So 13,000 years on, how do we know anything about this lost world?" "There are still clues to be found if you know where to look." "In the Bighorn Mountains of Wyoming is a hidden cave, recreated here, where over the millennia, thousands of animals have fallen to their deaths." "Preserved below the surface are bones dating all the way back to the Ice Age." "Remains of bison lie alongside antelope and rabbit but they're mixed with those of camels, extinct horses, giant wolves." "Even the mastodon is buried here, a long-dead relative of modern elephants." "And this was once a bear, but not like any bear in North America today." "Claw marks gouged into the cave wall show the bear was not killed outright by the fall - it made a desperate attempt to climb back out." "It was a short-faced bear, an Ice Age heavyweight." "What else can we tell about it from its bones?" "Its weight was more than 700 kilos, twice that of a grizzly bear today." "Upright, it would have stood four metres tall." "It was the largest flesh-eating mammal that ever walked the earth." "The Wyoming cave, appropriately christened 'Natural Trap,' provides a unique window on the Ice Age." "During its coldest era, much of North America was covered by huge ice sheets up to two miles thick." "But as the continent began to warm, the ice sheets started shrinking." "Corridors began to open up along the coast and through the mountains, letting people migrate south from Alaska for the first time." "Before them lay the almost limitless great plains stretching all the way from the Rocky Mountains to the Mississippi River and beyond to Mexico." "Across this area, the shifting ice left deep scars on the land." "It carved out thousands of lakes and ponds, and left the tapestry of streams and rivers that drain the plains." "The death throes of the last great Ice Age left a signature that we can read today." "These giant 'potholes' were left behind by blocks of buried ice that melted, leaving hollows that later filled with water." "For thousands of years since then, they've been vital pit stops for migrating birds, the millions of cranes, geese and ducks that follow ancient routes across the plains." "These rolling hills are made of debris dumped by the retreating ice." "It also left rich grasslands, able to support hundreds of millions of bison - vast herds drifting with the seasons, always searching for fresh grazing." "Pronghorn antelopes are unique to North America and among the toughest creatures on the plains." "Surviving year round in the open they must cope with freezing winter temperatures and scorching summer heat." "Every spring these open spaces echo to the sounds of courting sage grouse, as males compete to win a mate." "Migrating sandhill cranes strut and dance for their partners before heading further north towards their nesting grounds." "Small birds breed here, after an epic journey from their winter home." "These cliff swallows have flown thousands of miles from South America." "Mud from the ancient riverbanks is good for building nests." "It also holds more evidence that will help us to reconstruct the Ice Age past." "Every now and then, new clues surface hinting at what else might lie beneath." "In this dried up pond in South Dakota, known as Hot Springs, scientists unearthed great piles of bones." "What kind of creature died here?" "The bones reveal it stood four metres tall and weighed more than 10 tons." "There's nothing fitting that description living here today." "Here's the give-away:" "a pair of tusks two metres long, the trademark of a Columbian mammoth, the biggest animal to roam the Ice Age plains." "By comparing it to elephants in Africa today, can we shed light on how those Ice Age elephants lived and what they lived on?" "These are mammoth teeth - huge molars the size of bricks." "They have deep ridges very similar to those of modern elephants, suggesting mammoths, too, survived by grinding vast amounts of grass." "Plant fragments trapped between the ridges can still be identified today." "Thousands of years after this mammoth died, we know exactly what it ate for its last meal." "Grass is a tough, abrasive food." "Even with protective enamel ridges, these teeth would gradually have worn down." "But just like modern elephants, the mammoths had evolved a way to deal with this." "As one set of teeth was eroded, another grew up to take its place." "The evidence suggests they had six sets in all, to last a lifetime - up to 60 years." "The South Dakota mammoth didn't make it to old age and it was not alone." "The site turned out to be a mammoth graveyard, hiding more than 50 skeletons, all from animals in their prime." "There's no sign they were killed by hunters, so how did so many healthy mammoths die?" "The site was once a spring-fed pond, full of water." "Mammoths were tempted in to drink, but when they tried to climb back out the banks were steep and slippery." "Just like the short-faced bear, imprisoned underground, some became trapped." "Scavengers would have been attracted by the mammoths' plight." "The bones of wolf, coyote and the short-faced bear have also been recovered from the dried up sediment." "The search for food was probably their downfall too." "These prairie ponds are like time capsules, and they store another kind of data showing how the plains have changed across millennia." "Each spring, pollen from nearby plants is blown into the water." "It sinks and settles layer upon layer on the bottom, building into a databank of local plant life that we can still read today." "And grass pollens aren't the only clues still sandwiched in the sediment." "There are a wide variety of tree pollens too, from aspens, spruce and other trees, both conifers and deciduous." "This store of pollen paints a picture of the plains of 13,000 years ago, a picture that looks very different from the open prairie grassland of today." "But why did this region look so different back then?" "The ice sheets to the north, although retreating 13,000 years ago, still dominated the climate here." "It was much milder and wetter than today, ideal conditions for woodland to flourish." "This is how much of the northern plains must have looked when the first people arrived;" "not open prairie as it is now, but a parkland of trees and grassy meadows." "This is a relic of those times - the Osage orange." "Every autumn it produces these enormous fruits, huge numbers of them, more the size of grapefruits than mere oranges." "But there's no animal alive today that's big enough to pick and eat them, so this bumper crop just rots." "The Osage orange glory days are long gone, but its harvest was once an annual feast for many Ice Age animals, including browsing mammoths." "Fruit must have been a real treat for these grass eaters." "The Osage orange seeds were carried far across the plains, before being deposited pre-packed in their fertiliser 'grow-bags' ready to take root." "As the Ice Age waned, the milder climate and the mix of vegetation meant the plains were able to support a range of wildlife as diverse as Africa's Serengeti today." "There were at least five kinds of horse including a wild ass and another that resembled modern zebra." "And North America's very own antelope - the pronghorn." "13,000 years ago several different species roamed the plains." "The pronghorn lived alongside other grazers still around today, including bison." "This animal was common, too, but now it would seem very out of place." "Bigger than its modern relatives, the Ice Age camel was extremely hardy, able to eat almost any kind of food." "Elk, like many Ice Age animals, survive almost unchanged." "The rich parkland was ideal for these large deer." "But one creature more than any other has remained a constant symbol of the plains since people first set foot here - the bison." "Adult bison are formidable - two metres tall and weighing more than a tonne." "They too sheltered near the trees in winter, taking to the plains again in spring when new grass started sprouting." "Bison calves are born in summer and can run within a few hours of their birth." "They have no choice - the herd won't wait in its eternal quest to find new grazing." "Smaller grazers are still found here, too, but they stay put instead of wandering the plains." "Prairie dogs inhabit rambling subterranean 'towns' that stretch tens of square miles." "These highly social creatures stay within a short dash of their door, ready to retreat from predators or bad weather." "There's always maintenance work to do, but major renovations have to wait until after rain, when the soil is soft." "All this working and re-working helps the land recover from the impact of so many bigger feet and appetites." "At summer's end, male bison help to move the sun-baked soil, as the rutting season starts." "They roll in dust and paw the ground to try to dominate their rivals." "The dust bath also helps to dislodge irritating insects." "A prairie dog colony is usually surrounded by short, nutritious grass thanks to the many teeth in town." "This constant grazing stimulates fresh growth and also keeps the field of vision clear for spotting predators." "Larger neighbours are attracted to these verdant meadows, just as they were 13,000 years ago." "Columbian mammoths had to feed almost round the clock, to fuel their bulky bodies." "But as the Ice Age ended, food was not the mammoth's biggest problem." "A new and deadly predator began to infiltrate the plains, a match for any prey, even the mighty mammoth." "These people knew how to make lethal weapons, they left spear points, knife blades and other tools scattered all across the plains." "And they spread fast." "The evidence suggests it took them only a thousand years to spread across the entire northern continent." "What can we learn today about the lifestyle of these butchers of the plains?" "They left a string of clues to how they lived, including strange pyramids of rocks." "Inside are bones of animals that show how they were slaughtered and cut up for meat." "These cairns are thought to be cold-weather larders, marking prehistoric hunting camps." "When hunting parties had more meat than they could eat or carry, they would stash the surplus under these rocks to be collected later." "They seem to have used bones as markers." "In a Colorado gully, hunters carried out a mammoth massacre, leaving behind the remains of at least 16 animals." "The site recreated here contains a treasure trove of evidence relating to the mammoths' daily life." "Again by comparing mammoth bones to elephants, we can calculate the sex and age of all the animals that died here and deduce the make-up of a Columbian mammoth herd." "These are the bones of juveniles, up to around 14 years old, both males and females." "Several adults lie here, too, all females," "including one huge specimen, at least 40 years old." "This range of age and sex exactly matches that of a modern-day African elephant herd." "An older matriarch, the leader of the herd, is accompanied by her daughters and other female relatives and they in turn are with their young, both male and female." "But where were the adult males when this herd was destroyed?" "A unique clue to their lives was uncovered in Nebraska." "Recreated here are the skulls of two gigantic males that died with their tusks interlocked." "But how could this have happened?" "Again, our best bet is to look at elephant society." "During the breeding season, sexually mature bull elephants fight for access to the female herds." "The tangled tusks are direct evidence that mammoths were aggressive, too." "Because these two bull mammoths both had broken tusks, they could have fought at closer quarters than they would do normally, twisting and turning they became locked in a deadly embrace." "Even more bizarre, this twist of fate then caused a third fatality - beneath one mammoth's shoulder blade was the skull of a coyote, pressed into the ground." "While we can only speculate on just how the coyote died, it's likely it was scavenging around the decomposing carcasses when one caved in and crushed it." "Coyotes are still on the plains today." "They hunt their food as well as scavenge carcasses, but small live prey can be more trouble than large dead ones." "Prairie dogs are always on alert and once a trespasser is spotted, the entire town vanishes into thin air." "Prairie dogs aren't really dogs at all - they're rodents - but coyotes are full-blooded members of the canine clan and like all dogs, they sometimes hunt in groups to tackle bigger prey." "Some prey, however, are just too big, even for a pack of coyotes." "But 13,000 years ago, there was another kind of canine hunter here one that gave even the bison a run for their money." "The wolf..." "the ultimate pack hunter." "A lone wolf weighs as much as four coyotes, but one on one it's still no match for a bison." "Wolves, though, live and hunt in packs of up to 15, and when they launch a co-operative attack, they're devastating." "First they get the bison on the run, then filter out the weak and vulnerable and select the perfect target." "Striking together wolves can bring down prey many times their own size." "A million such chases must have taken place across these plains and we can still find echoes of these distant life or death encounters." "Not all evidence lies locked in bone and rock." "These pronghorn antelopes, among the great survivors of the Ice Age, reveal a lot about the distant past." "As well as being tough enough to stand extremes of temperature, they're famous for their speed." "A sprinting pronghorn can top 60 miles an hour and cruise at 30 for several hours." "This kind of speed requires a very finely tuned physique." "Pronghorn have a massive heart and run with their mouths gaping open, forcing extra air into their huge lungs." "But what's the point?" "No predator can run this fast, even the wolves can only manage 40 miles an hour." "So why do pronghorn feel this need for speed?" "This is why." "Once there was a predator here that could outrun the pronghorn - a cheetah." "13,000 years ago, the Ice Age cheetah was the pronghorn's greatest enemy and pronghorn would have needed all their amazing speed." "The American cheetah was larger than its African cousin, but it had the same Achilles heel." "A cheetah's high-performance muscles overheat in minutes and, unlike pronghorn, it can't switch to cruising speed." "So if the pronghorn managed to outrun the cheetah for the crucial first few hundred metres, it would probably survive." "The cheetah hasn't roamed the plains of North America for thousands of years, but pronghorn are still primed for the chase." "Other extinct links to Africa have been found in caves deep in the Ozark mountains of Missouri." "Preserved in mud were huge prints recreated here, more than 18 centimetres wide." "What could have made them?" "They belong to another Ice Age cat, the top cat of the plains - a lion." "Larger than any lion alive today, this would have been an awesome predator." "These caves were probably its winter den." "With such abundant game down on the plains, this hunter's life must have been pretty good." "Sheer size and power, and the benefit of life within a pride made it the unmatched ruler of the plains." "By looking at the lions of Africa today, we can imagine how these Ice Age cats once lived - in small prides based around a group of hunting females." "Like wolves, lions work together to win larger prey." "After a leading hunter launches the attack, the others move in, helping to dispatch the victim with a suffocating bite." "But even for these rulers of the plains, the good life had to end." "They would be toppled by another predator with even sharper skills." "The Ice Age lions joined the list of victims, animals that had lived here for hundreds of millennia, but were soon lost forever." "Today few signs remain that any of them were ever here - odd traces scattered far and wide across the plains." "But if we piece together bones and teeth, plant fragments and the clues from animals alive today, we can begin to bring a lost world back to life." "So let's go back in time, back 13,000 years, to relive one day in the life of North America's great Ice Age plains." "It's early morning at the end of a long, hot summer." "Even major rivers are beginning to run low." "A Columbian mammoth herd follows the river valley, they can't risk straying far from water." "Once they've quenched their thirst, the next priority is food." "They head out to the nearby meadows, where they'll graze most of the day, processing mountains of dry grass." "Autumn is mating season and a couple of nomadic males have started shadowing the herd." "By sparring, they decide who will have access to the females coming into heat," "who will father the next generation." "Most power struggles are resolved through ritual intimidation." "But if two evenly matched males cross paths, this posturing can escalate into a full-blown fight." "Both these opponents have a broken tusk letting them get closer to each other during combat." "Suddenly, a freak clash leaves them in a deadlock, inextricably entwined." "If they can't free themselves, they'll both end up the losers." "As a constant source of food and water, even when there's been no rain for months, this valley draws thousands of other grazers." "And all this meat in one small area attracts a scavenger - the short-faced bear." "Led by his super sensitive nose, his long limbs carry him many miles a day in search of carrion." "He's picked up a scent, but where's the carcass?" "Sometimes the smaller, speedier scavenger gets there first, on this occasion - a coyote." "Right now the short-faced bear will take whatever he can get - he hasn't had a decent meal in days, and needs at least one good-sized carcass every week to stay alive." "This time the coyote's left him nothing but the skeleton." "But with his huge, bone-crunching jaws the bear can crack them open for the marrow locked inside." "With water so scarce elsewhere, animals from miles around converge here in the valley," "which is good news for the local lions - their pride territory is now overflowing with food." "Once the midday heat subsides, the females rouse themselves to hunt." "The scene is set for a daily Ice Age drama." "Only the very largest are safe now." "Patience is the key." "The lionesses close in, waiting for their opportunity." "The first charge causes chaos but this is just what the lions want." "In the melee, they've already pinpointed their prey." "The leader pounces, and a horse is down." "Meanwhile, the spooked herds stampede up the valley." "But they're running straight into another trap - a hidden cave, already full of Ice Age victims." "And now it claims another." "Above ground, the members of the valley pride - mothers, sisters and cubs feast." "But their success hasn't gone unnoticed." "From many miles away, the short-faced bear can smell blood on the breeze." "He sniffs his way towards the source." "Meanwhile, satisfied and sleepy, the pride settles down for a snooze." "More than twice the weight of the pride's most powerful lion, the short-faced bear is a daunting sight." "Its trump card is to use its massive size to frighten hunters from their kill." "But the lions won't give up their hard-won meal without a fight." "This time, the bear's scare tactics just don't work." "The lions' numbers are against him and, despite his gnawing hunger, he backs down." "The autumn winds are rising, carrying another scent across the plains and once again the bear's nose sets his course." "This trail leads to the cave and the freshly dead bison, just out of reach." "Hunger makes the bear risk everything." "He falls and joins the bison in its tomb." "Now he can eat his fill, but after that there's no way out." "In time he'll be just one more Ice Age specimen." "Outside, another group of predators head for their cave at dusk, pack hunters even more effective than the lion or the wolf." "Still relatively new here, they'll eventually transform the Ice Age plains, and build their own future by exploiting the herds of the American Serengeti." "Even the giants that now dominate this Ice Age world will soon be gone." "But they'll leave clues behind, and one day distant generations will pick up their trail and tell their story." "Downtown L.A., the ultimate modern American city." "But Los Angeles' skyscrapers are built over the graves of thousands of extinct Ice Age beasts." "Today all we have are memorials to these vanished animals." "But imagine if they had survived into present day." "They would have had to adjust to a very human world." "The reality is mammoths never made it beyond the end of the last Ice Age," "but many other creatures did." "And over the past 14,000 years or so, they've had to adapt to an increasingly human landscape, a landscape of concrete and steel." "In this programme we will travel back into the past to investigate why the giant beasts of North America became extinct." "And to find out how those animals that did survive have adapted to life in our modern world." "To find the answers, we need to rewind history around 14,000 years to a time when the first people set foot in North America." "The continent was about to undergo a profound change, a change these new arrivals may have played a part in." "Throughout the Ice Age" "North America was home to a variety of giant creatures." "But in little more than a thousand years of the first humans arriving, almost two thirds of the largest animals were extinct." "What role did people play in this mass extinction?" "To learn about their lives you have to look at the clues they left behind." "Archaeological finds tell us that the first people in North America had an advanced stone age technology." "They were master flint knappers, meticulously chipping and sharpening pieces of flint to make spears and cutting tools." "From the examples they left behind, it's obvious they were well equipped to hunt." "And we know from spear points found alongside mammoth remains that these hunters tackled even the biggest beasts on the continent." "Mammoths would have been a prized source of protein, providing enough meat to feed their families for weeks." "The hunters probably worked in pairs or small groups." "Any mammoth straying from its own herd would have been singled out." "But even on its own, a mammoth was still highly dangerous and an attack required stealth and teamwork." "One of the hunters may have acted as a decoy, distracting the animal while others surrounded it." "And these hunters had another trick up their sleeve." "Using a specially crafted wooden stick called an atlatl, they were able to launch sharp pointed darts more than 40 metres." "So we know these people were efficient hunters, but could they really have wiped out all the mammoths on the North American continent?" "Today, the remains of mammoths, in particular their tusks, may help answer that question." "To read the clues contained within these tusks you need to look at the mammoth's closest living relative - the elephant." "Elephant tusks grow throughout their lives, with the tip being the oldest part." "Mammoth tusks show the same pattern of growth as modern elephants." "Each year of life is represented by a ring just like tree rings." "But tusks can also be a record of the more stressful periods in an elephant's life." "As bulls mature, they're forced out of the family group and have to fight to survive." "During this stressful time, they don't have so much energy for growth, so the space between each ring is narrower." "These same signs appear in young male mammoth tusks, but those living in North America at the end of the Ice Age laid down their stress rings 3 years earlier than usual." "In other words, it seems that young males were leaving the herd at an earlier age." "Some scientists believe the only thing that could cause such a major change in mammoths' social structure would be hunting by humans." "If hunting pressure was extreme enough to push the mammoths to extinction, then we would expect them to survive in areas that people couldn't reach." "And for a while they did here, on Wrangel Island, off the coast of Siberia." "There are no mammoths on Wrangel Island today, but it is home to another large animal - the polar bear." "And there is evidence that polar bears and mammoths once lived side by side during the last Ice Age." "They would have shared the island's meagre offerings." "This inhospitable and isolated place seems to have been a sanctuary for mammoths." "The Wrangel Island herds were the last on the planet to survive." "Remarkably, they survived here long after their North American relatives had all died out." "But they were still on borrowed time." "When people finally reached Wrangel Island 4,000 years ago, these last remaining mammoths also became extinct." "The events on Wrangel Island mirrored what had happened on the North American continent." "Mammoths only became extinct after they came into contact with people." "But there is a problem with the idea that hunting caused the mass extinction." "Mammoths were not the only animals to disappear." "Camels survived for millions of years in North America, but disappeared around the same time as the mammoths." "Wild horses first evolved here and became dominant grazers." "Yet they, too, vanished soon after the Ice Age ended." "But there's little evidence to suggest that humans hunted horses or camels." "This seems to go against the hunting argument." "So what else could have triggered such large-scale extinctions?" "The other major possibility is climate change." "The ending of the Ice Age was a turbulent, erratic period." "In some areas rain patterns were shifting, bringing moisture back to dry landscapes and turning grassland into forest." "Other regions of the continent were plunged into prolonged periods of drought." "For grazers such as horses, this led to a massive change in habitat, one they were not flexible enough to overcome." "As the land dried out, many grass-eaters disappeared." "We may never know for certain what killed off most of the larger animals at the end of the Ice Age." "We do know it was a time of coincidence - people were arriving just as the climate was in a state of change." "Both may have played their part." "Whichever was responsible, more than 70 species vanished for good." "But some large animals did survive, and still live here today." "Sabre-tooths died out, but another big cat survived." "The puma may have been more able to adapt because its diet is more varied, and includes small prey." "The grizzly bear also lived through the post Ice Age changes and now thrives in North America." "Once again, a varied diet of meat and plants made it a versatile survivor." "The moose is now the largest browser on the continent." "During the last Ice Age moose were restricted to the far north but, after the ice melted, they spread south." "They took the place of mastodons and the larger stag moose, both of which became extinct." "Bison, too, were to benefit from the post Ice Age changes." "They managed to survive the drought, eventually expanding in number to replace the horse as dominant grazer." "As ruminants with multi-chambered stomachs bison can extract more nutrients from grass and this may help explain why they survived when other grazers such as the wild horses did not." "While all these creatures were adapting to their changing landscape, another animal was just beginning to make North America its home." "It's thought the dog arrived with early people and its descendants are still with us today." "The Carolina dog lives in the woods of South Carolina." "Like most primitive dogs, it makes its den in the ground or in hollow tree trunks." "The Carolina dog is often called the American dingo." "It does look like its Australian relative, but links between the two may go deeper than that." "Genetic analysis of the Carolina dogs suggests they are closely related to primitive wild dogs like the dingo and may trace their ancestry all the way back to the first dogs to enter North America." "The Carolina dogs are pack animals, with a strict hierarchy topped by an alpha male." "Like most wild dogs they hunt in groups, but many of the kills they make are small." "Rabbits and small rodents make up a large part of their diet in what can become a collective feeding frenzy." "At the end of the Ice Age these dogs' ancestors also had access to other sources of food." "They may have hung around the camps of early native people, scavenging for scraps." "But although they lived on the fringes of human society, the early wild dogs were certainly not pets." "Exactly when they arrived in North America is still uncertain, but it's likely that they slipped in after the extinction of the Ice Age beasts, during a time of massive change." "Eventually, the continent became more settled." "Over the next few thousand years, people adapted to the many regions of the continent and their varying lifestyles were shaped by the landscape they lived in." "Then, more than 14,000 years after the first people set foot in North America, another wave of immigrants brought changes that would have a dramatic impact on the landscape and wildlife of the New World." "Just over 500 years ago," "Europeans arrived in North America." "And with these colonisers came an animal that hadn't been seen here for thousands of years." "The horse returned to the Americas, now tamed and carrying the Spanish conquistadors." "This new form of transport was rapidly adopted by the native people, which was bad news for some native animals." "Bison had once lived alongside the wild horses of North America and had prospered at the end of the Ice Age while the horses became extinct." "But now the new tame horse became the bison's enemy." "The horse's speed and stamina gave native people an advantage over their prey that they never had before." "The horse was an even bigger ally to the increasing number of European settlers spreading out across the continent." "They killed millions of bison for their meat and hides." "By the mid-1800s the horse and the cowboy had come to symbolise the wild west." "And of course, with the cowboys came cattle." "As the bison quickly vanished from the landscape, cattle filled their place." "Meanwhile increasing numbers of the tame horses escaped into the wild." "These feral horses became known by the Spanish name: mustang." "They put extra pressure on the dwindling bison numbers by competing for their grazing sites and drinking holes." "Mustangs formed social groups led by a dominant stallion, echoing their prehistoric relatives that lived here during the Ice Age." "Bred to carry the weight of a rider, mustangs are larger than those early wild horses but they still display the same kind of behaviour." "By the early 1800s the wild horse was well and truly back in North America." "But how did other wildlife on the continent survive alongside growing human populations?" "Some wild creatures did the reverse of mustangs by becoming tame and choosing to live close to people." "The purple martin became an unofficial mascot for native inhabitants in the eastern half of the continent." "Here people erected special nesting sites to encourage the birds to stay." "Where purple martins had once laid their eggs in hollow trees, in time they came to rely almost totally on people to provide nests for them." "These artificial nests were made from dried out squashes known as gourds." "The shape made them perfect nesting sites for these birds." "But what triggered this special relationship in the first place?" "It's possible the insect-eating martins helped to control pests living around native American camps." "Whatever the original reason, the traditional tie between people and purple martins survives to this day." "But now, in keeping with the modern world, hollow gourds have often been replaced by high-rise apartment blocks." "This special relationship between purple martins and people is one of the few in North America to cross cultural boundaries between native groups and European settlers." "Other animals to cross this cultural divide did so for different reasons." "More than 50 million wild turkeys were living in North America when the first Europeans arrived." "They were occasionally hunted by the native people, but the European settlers had a taste for turkey and they took this to extremes." "As hunting intensified, wild turkey populations plummeted." "The turkey became a central part of Thanksgiving Day celebrations and was almost hunted to extinction." "At first the Europeans relied heavily on local food supplied by native people." "But as they settled in, their farming practices began to shape the landscape of North America." "The plough allowed them to farm larger areas of land, helping to feed the expanding population." "While this new type of agriculture robbed many animals of their habitat, others were to reap the benefits." "Birds such as grackles, cowbirds and redwing blackbirds, exploded in numbers, feeding off the waste remains of farming." "These pest birds were already common around small native farms in the east." "Now large scale farming of crops such as corn, wheat and barley fuelled their numbers to epidemic proportions." "Despite these pests," "North America's agriculture kept on booming, becoming big business." "Great swathes of a once wild landscape have been turned over to farming." "And farming fuelled the growth of another habitat, one that would become an even bigger challenge to North America's wildlife." "The modern city was born." "The city is an artificial environment, built around the needs of millions of people." "And yet it also offers unexpected opportunities for wildlife." "This burrowing owl lives in one of the biggest, hi-tech urban sprawls of North America." "It maintains a tenacious foothold in Silicon Valley." "Burrowing owls originally lived on open prairies, but they've been forced to adapt to city life because the urban environment has grown around them." "They survive by occupying any tiny sliver of grassland that remains." "Like many city animals, they take advantage of the darkness to protect them, and move around mostly at night." "These adaptable birds traditionally nest in the burrows of prairie dogs, but in the city a piece of old pipe will do." "The parents split their duties the father does much of the hunting, but in this case it's the mother that actually feeds the chicks." "The burrowing owl's ability to hover gives it time to judge an attack before pouncing on its prey." "The owls can raise anything from one to 12 chicks in a summer season." "To survive, their young will have to quickly learn to negotiate the dangers of city life." "Longer hunting trips are sometimes necessary as open land disappears." "But so long as the city can still provide food and shelter, these owls will remain a part of the urban landscape." "A few hundred miles south of Silicon Valley, another city has grown up on the edge of a desert." "This is Bakersfield, California." "It sits on an underground reservoir of water, enabling its residents to live in a suburban idyll." "This modern day oasis has provided sanctuary for a rare animal, one that emerges at night." "The San Joaquin kit fox is one of the smallest and rarest foxes in the world." "Yet, remarkably, it flourishes on Bakersfield's busy street corners." "Although many of these city foxes do get killed by cars, the population as a whole is thriving." "That's because the regular supply of water means a regular supply of prey, including voles and ground squirrels." "Playing on the streets at night is dangerous, but for the pups, it's vital for improving their co-ordination." "Parents keep a vigilant eye on their antics." "Despite the hazards of city life, the Bakersfield kit foxes are now crucial to the overall survival of the species." "The promise of an easy source of food is a good reason why animals live in cities, especially at times of year when food is hardest to find in the wild." "During the winter months Anchorage in Alaska is home to North America's largest browser - the moose." "But a moose during the day is a little obvious, so they prefer to move around by night." "While most of the human population sleeps, the moose wander the streets in search of food." "Moose mainly browse on trees and shrubs but they will also sample something new - they have a soft spot for pumpkins left out after Halloween." "As many as a thousand moose may enter Anchorage in winter." "Snowfall here is lower than in surrounding hills and gardens offer a tempting spread of food." "In fact, moose were in this area long before the city existed and Anchorage inhabitants are understanding of their local vandals." "Unfortunately, this tolerance sometimes comes at a cost." "Christmas decorations are a minor inconvenience to a hungry moose." "But there's another reason why the city centre is a tempting winter hangout." "It's one place where their major predator, the wolf, rarely dares to go." "It may seem strange, but human habitats are often safer for wildlife than the real wild." "Black skimmers usually nest on beaches, but not here in Texas." "This disused car park is a near perfect location for raising chicks" "and only a short flight from a plentiful supply of food." "Skimmers get their name from their unusual feeding technique - their extended lower bill detects fish just below the water surface." "The heavy use of east coast beaches by people has threatened skimmer numbers." "It's ironic that this man made car park, made out of crushed oyster shell, should become a substitute." "Skimmers raise their chicks on a fish diet." "But they serve the portions whole, which can cause problems for their young." "The increasingly human landscape of North America can make wildlife spectacles a rare event." "But there are situations when it brings nature closer to people." "That's exactly what has happened here at this power plant in Florida." "These are West Indian manatees - residents of the Florida coast." "People and manatees don't usually get along." "Increasing boat traffic has become a big threat to manatees and some bear the scars of painful encounters with boat propellers." "But there is at least one place in Florida where the manatees benefit from humans being around." "Clean, hot water released from this power plant turns a man-made inlet into a hot tub." "And during winter months, when sea temperatures drop below 20 degrees centigrade, manatees gather here to keep warm." "It's actually an artificial version of the natural hot springs where manatees traditionally congregate." "But this particular location seems to be extremely popular." "During the coldest spells, more than 300 manatees can gather here." "With so many of these shy creatures in one place, the power plant has become a tourist attraction." "It may not be the most scenic setting, but this is a unique chance to see one of the largest gatherings of manatees in the world." "People have become dependent on industry to support their modern lifestyle." "So too it seems has some of North America's wildlife." "Every September, the skies over Portland, Oregon become crowded with Vaux's swifts." "These birds have chosen a 30-metre chimney stack as a place to roost." "Tens of thousands funnel down into the disused chimney, where they huddle together for the night." "Vaux's swifts traditionally roost communally in hollow trees, but as many of North America's forests are destroyed, they've turned to man-made structures." "This mass roosting takes place soon after the summer nesting season." "It's a chance for the birds to moult before they fly south for the winter." "As Vaux's swift numbers reach a peak in mid September, they attract attention from the locals." "Coopers hawks and peregrines pluck a meal from the tumbling mass of birds." "In as little as 20 minutes, as many as 40 thousand swifts pack into the chimney for the night." "While a Portland chimney has become a substitute for a tree, another roosting creature has chosen a road bridge in Austin, Texas as its cave." "Visitors to Austin have to wait till evening for a glimpse of what lurks within the bridge." "As the sun goes down," "Mexican free-tailed bats begin a breath-taking commute out of the city." "This exodus only takes place in summer." "Free-tailed bats arrive in Texas for the spring, returning to Mexico for the winter." "More than a million of them leave the city at dusk and head into surrounding countryside to feed on insects." "The sky over Austin swarms with these aerial commuters." "It's incredible that so many bats cram into tiny spaces underneath the bridge." "But the battle for living space is now an everyday fact of city life." "The most populated North American city is New York." "Here, space is a precious commodity, with more than 8 million people fighting for their share." "With so little ground space left, having a garden can require a head for heights." "It's difficult to imagine any animal getting a foothold in this bustling city." "But some do." "The red-tailed hawk is well known in mid town Manhattan." "It manages to survive here because New York has the ultimate in urban gardens " "Central Park." "This park, created in the mid 1800s, has become a focal point for wildlife and the people of Manhattan." "It's also prime hunting ground for red-tailed hawks." "And they have the perfect nesting site right next to it." "They've moved in on the top floor of this expensive Manhattan apartment block." "It acts like a surrogate tree supporting their large nest." "Their high-rise residence also provides a perfect lookout and a launch pad for ambushing prey." "A meaty New York diet means these birds continue to survive in North America's most hectic city." "Despite our increasingly urban lifestyles, we still have a deep-rooted desire to connect with nature." "And in modern day North America it's possible to fulfil that desire in all manner of ways." "This may look like a safari through the African savannah." "In fact, it's a theme park in Florida, and it allows people to experience a world outside their own." "In some ways they are visiting a land from another time." "14,000 years ago large parts of North America's landscape and wildlife were just like the savannah of modern Africa." "With a stretch of our imagination, we can still put ourselves in the shoes of the first people who explored that vast, dramatic landscape and encountered giants never seen before." "In this series we have seen how fossil bones and other evidence can provide clues to that distant past." "And that evidence has helped to recreate a continent that no longer exists " "a lost Wild New World."