"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 a 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 lce Age, long before the first city was born  to look through the eyes of the very first people  and experience a Wild New World." "ln 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 lce Age," "14,000 years ago." "By searching for evidence that still survives today, we'll reconstruct the landscape and the wildlife of prehistoric North America." "During the last lce Age, massive glaciers covered half of North America." "But to the far Northwest 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." "North America was only colonised by people around 14,000 years ago and Beringia is believed to be the starting point from which they spread out across the continent." "ln this program 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 peak 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 tons 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 fourteen thousand 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, the mammoth's 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 four 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." "ln one remarkable discovery, recreated here, the head and hide of a large carcass was exposed a unique opportunity for scientists to tap some ice Age secrets." "The remains were of an extinct steppe bison, a longer-horned relative of the North American bison of today." "An adult bull that must have died and been 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 lce 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 harrying 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 gold mine 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 gouges 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 lce Age bison had a set of puncture marks on its snout around nine centimetres 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% 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 1 ,000 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 lce Age, the Bering Land Bridge formed once more and this time it allowed a different colonist to cross." "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'd choose to make a campsite." "But if you were a hunter what you needed 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 wet land of forests, boggy tundra, lakes and rivers." "Rivers that still churn out fresh clues to the ice age past." "This is a brick-sized tooth and it belonged to a woolly mammoth." "lts narrow ridges of enamel tell us more about how mammoths lived." "Studies of modern elephants suggest that the more grass you eat the more ridges you need ..." "And mammoth teeth have even more ridges than those of any elephants... lt 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 'mammoth 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 2 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." "ln 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." "ln the autumn Dall rams like the mammoths and the musk oxen become focused on the urge to mate." "The male flicks the air with his tongue, to test if a 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 minus 50 degrees Centigrade, thanks to their chill-proof woolly coats." "ln 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 a 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 helped to minimise heat loss... the opposite effect to 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 air sacs, which pre-warm cold air while breathing in and retain precious moisture before breathing out." "So saiga, too, were well equipped to live in the cold, dry climate of Beringia." "Today they're only found in another bleak environment the steppes of Central Asia." "Some lce Age animals took a totally different approach to surviving the winter." "Arctic ground squirrels feed up in autumn, building up as much body fat as possible and 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 minus three degrees Centigrade." "But thanks to a biochemical super-cooling 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 co-operate 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 brought 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 grow 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 gold mine 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 it taken by a predator?" "Perhaps young elephants provide some clues... they stick close to their mother's 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 rarely 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 early 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 of 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 who 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 wind chill 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 daunting 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're 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... but 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 wary 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 60 years' experience of putting lions in their place... ln 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." "Next week," "Wild New World explores the prehistoric canyon lands," "Home of vast Columbia mammoths and the most impressive hunters, the saber-toothed cat." "Meanwhile, find out how newly creative past on bbc.co.uk/nature"