"Narrator:" "Our planet is alive." "From the shores of Antarctica to the plains of Africa it's a world of great beauty and stunning diversity." "But there is also a dark side." "Life is a war filled with predation ... rivalry... and brutality." "But what created this great drama called life with its beauty and its violence?" "Breakthroughs in our understanding of evolution can now explain how animal life arose how it fought to survive in the ancient past... and still struggles today." "We now know how behavior has been shaped by conflict... and battles for mates... by predators chasing prey... through the tensions in family life... and by mindgames of intelligence." "We share the earth of life's four-billion-year war for survival." "The astounding variety of winners in this ancient struggle is the triumph of life." "NARRATOR:" "A tropical shore, 65 million years ago." "Life has already existed for more than three billion years." "The struggle to survive continues." "Trudontid dinosaurs scavenge the beaches." "Primitive seabirds return from a hard day's fishing." "Below the waves, turtles navigate dangerous waters." "Pliosaurs, huge predatory reptiles, patrol the coast." "The fastest and most alert survive." "Like all living things, they fight to continue their lives and are compelled to nest, despite the dangers." "In the ancient battle for survival there have always been winners and losers-- those that live and those that die." "But dinosaurs, not turtles, were doomed." "Today, only fossil bones testify to the dinosaurs' ancient rule." "But life itself survived." "Turtles still hatch on tropical beaches." "The world has changed in 65 million years." "But the fight to survive remains the same." "Many set out, but not all will reach the sea." "Today's predators are waiting." "But they must run the gauntlet." "The race of their lives is on." "Life's path is full of obstacles the journey always a struggle." "Survival odds are not random." "Each individual is a unique product of its parents and some have the edge on others." "Moving swiftly in company is safest." "Getting left behind or lost can be fatal." "While the weak succumb, the strong struggle on." "Vultures take a heavy toll on both." "Frigate birds now launch aerial attacks." "Stragglers fall prey to forest mammals coatis and coyotes." "While the race for the sea continues one hatchling heads inland." "But this is no place for a sea turtle." "For other creatures the land has long provided huge opportunities." "Myriad animals have escaped the sea and now carve out a living here." "Crocodiles have barely changed since the age of dinosaurs while birds have taken many forms." "Mammals have also diversified in body and behavior." "All living things are triumphant veterans of the four-billion-year war called evolution which has raged since life first appeared." "Survival skills stay sharp as they are tested anew every moment of every day." "The cast of life's drama is never fixed and changes over time as the victorious prevail." "The rules of the war are harsh." "Some individuals fail;" "others triumph." "Only winners emerging from the battleground of life carry their family line forward through time." "Despite the losses some youngsters do make it through the ranks of predators which have gorged until they can eat no more." "They now face life's continuing challenge." "Those fittest for the rigors ahead may one day return to breed themselves." "As the secrets of each generation's success are passed on, life evolves." "But clues to life's shared ancestry remain hidden within every animal." "Skeletons reveal remarkable similarities." "Bony fingers, limbs and backbones, though subtly changed are recognizable in very different vertebrates." "Birds, whales and turtles are far more alike than they appear on the surface." "Each living form began the journey that shaped it way back in the past." "A turtle about to hatch is clearly a turtle with an obvious shell and flippers." "A week or so earlier, these features are less distinct." "A young embryo could be almost any vertebrate with spine, eyes and four stubby limbs." "Beyond that, it's more fishlike then just a mass of dividing cells." "Finally, it's a single cell but one containing the complete blueprint for a turtle." "At the heart of the cell lie the chromosomes... and within them lies the key to life itself the most incredible substance on earth a unique molecule in the shape of a double helix:" "DNA." "Evolution is driven by the way DNA copies itself with near-perfect accuracy and the information it contains." "Its genes shapes life's varied patterns." "African hunting dogs are distinct from other kinds of dog and individuals differ from each other in many ways including the unique markings on each dog's coat." "They get their looks from their parents, through their genes but they also inherit much more." "Even the urge to hunt, vital to their survival is built into them from birth." "Only good hunters live to breed." "A pack has just one breeding male and his distinctive white tail is mirrored in some of his pups back at the den." "Not all look the same since half their genes come from their darker mother." "With a mix of genes from two successful parents they've a chance to grow up strong and to continue their family line." "Genes shape every detail of animal form." "Some have brought recent innovations but many originated way back in time and have flowed through countless generations of triumphant life." "But how did life begin?" "What kind of creatures were the ancestors of those alive today?" "And how did the first genes, the original threads of life, arise?" "Primeval earth, four billion years ago." "The toxic air was devoid of oxygen." "Molten lava spewed into a noxious sea." "And yet these were the perfect conditions for the building blocks of life to form." "Such foul waters may have been the crucibles of creation." "Chemicals rained in and ultraviolet radiation and lightning bombarded them." "An organic soup gradually formed." "All was chaos, but order and complexity somehow emerged." "A very special molecule with an elegant spiral shape arose." "It alone copied itself faster than it was destroyed and multiplied." "This renewal was the origin of life and once it found protection inside cell walls life was set to transform the planet." "When cells first trapped the sun's energy 3½ billion years ago, life began to blossom." "The oceans teemed with simple plants and mats of them layered with sediment built the world's first living monuments-- stromatolites." "For over a billion years, these three-foot-high mounds were the pinnacles of life's progress but the Earth would be transformed by their waste-- oxygen." "This new gas, at first toxic to all life gave rise to the ozone layer." "Shielded for the first time from the sun's damaging ultraviolet rays life now made huge advances." "Plants, which had produced oxygen in the first place now came under threat from primitive animals that thrived on oxygen and consumed them." "Amoebae engulfed plants." "Ciliates wafted them inside." "Two billion years ago single-celled animals first did what grazing mammals do now." "They used oxygen to burn up plant food." "But how did the spectacle of today arise from such simple origins?" "Progress came when identical cells teamed up to form co-operative bodies." "Then life really moved on as cells specialized." "In jellyfish, some gave propulsion, others caught food." "Multicelled life was now taking shape." "The advance was driven by genes deep within." "A recent breakthrough in understanding how genes organize bodies has shed new light on the evolution of complex animals." "As embryos develop, some genes control which cells do what." "It was the emergence of these special genes which organize bodies into segments with head ends and tail ends that allowed life to take off like never before." "550 million years ago life exploded into a multitude of new, complex forms." "Many of those classic designs survive today." "Segmented worms marched over the seabed." "Life began to move in more elaborate ways." "New, strangely shaped animals appeared encased in tough skeletons with flexible joints." "The ancestors of sea spiders and crustaceans were on the move." "Genes that built better eyes and successful body shapes survived." "The pace of life increased and new dynamic breeds of animal preyed on one another." "Defense became vital and armor plating and spines proliferated." "Predatory worms could be defeated by tough shells and escape maneuvers." "With genes shaping life like never before all the basic animal groups alive today emerged in just 50 million years." "The previous three billion had led to nothing more complex than jellyfish." "Life was also threatened by the first large predator." "More than three feet long" "Anomalocariswas the scourge of the ancient seas." "But the big predator's days were numbered for a little creature had evolved whose line would take over the world." "Pikaia gently filtered food from water as lancelets still do today." "What made Pikaia special and ancestral to our own vertebrate line was its spine of cartilage supporting its muscles." "This light, strong design allowed speedy escapes." "But the ancient seas were still dominated by invertebrates." "Their heavily armed hordes were the top predators and scavengers for another 100 million years." "Today's crustaceans reflect that ancient armored world." "But the invertebrates are not the force they once were." "Alongside these hardened battlers the vertebrates survived, and one line evolved into fish." "They had no jaws like today's lampreys but compared to most invertebrates they had better eyesight and sharper brains." "When it came to alertness and reaction speed the invertebrates were beaten." "Fish became faster and sleeker, and far more numerous." "They developed a bony spine, and crucially, toothy jaws." "The sea became a much more dangerous place." "While the oceans were full of life the virgin land beyond the sea lay empty." "But 450 million years ago things were about to change." "Life invaded from the sea." "These strange creatures are horseshoe crabs ancient relatives of spiders." "To this day they emerge on just a few tides a year as their ancestors have done for hundreds of millions of years." "They come to mate at the edge of the sea." "Females burrow into the sand and lay their eggs beyond the reach, of the oceans hungry hordes." "Once, they had the beaches to themselves but today, flocks of birds descend." "Gulls gorge on eggs exposed by the waves... and vast numbers of shore birds join this annual feast." "Ancient life and modern life now converge as horseshoe crabs and birds fight the ongoing battle for survival." "Flipped over by waves, some crabs are stranded." "They soon die as their gills dry out." "But most live on." "Horseshoe crabs have barely changed in hundreds of millions of years and continue a successful way of life." "Strong skeletons allow them to venture briefly onto land but they remain creatures of the sea." "But such pioneers were just the first wave of life to reach the land." "By 400 million years ago much of the earth was cloaked in green." "Plants had colonized fresh waters and spread onto land." "Once they were established, animals soon followed." "Centipedes were among the first land creatures." "They developed simple lungs and skin that kept vital water in." "Scorpions, cousins of the horseshoe crabs also made an early move onto land." "Their line of eight-legged predators has spread far and wide since then." "The invertebrates were the first animals ashore but others were not far behind." "Fish penetrated weed-choked lagoons." "Using bony fins they forced their way through the tangles to stalk prey." "As competition increased fish sought new pastures to hunt in." "Fins became more and more like legs." "The vertebrates were on the verge of a breakthrough." "The first amphibians emerged from the swamp some 370 million years ago." "Their soft, moist skins absorbed some oxygen and simple lungs allowed them to breathe air." "The exertion of hauling themselves over land required plenty of fuel." "But the land was now crawling with life." "The first flightless insects made easy prey." "Despite delicate skin many amphibians came to live on land as the feeding was so good but they were confined to damp places." "The insects went much further." "320 million years ago some forms underwent a remarkable change." "Under the control of new genes they transformed into very different creatures." "They grew wings." "Life was about to conquer the air as well as the land." "The power of flight gave insects a huge advantage." "They now number more than half of all kinds of animal on earth today and they've reached almost every corner of the planet." "They have invaded some of the driest places on earth." "Ants are by far the most numerous insects of all and their social habits have helped them to succeed around the world." "But here, they are not alone." "Reptiles evolved from amphibians but with a tougher, waterproof skin-- ventured where amphibians could not go." "The skin of horned lizards can even resist attack by ants... at least most of the time." "Reptiles also pioneered another survival strategy:" "Waterproof eggs allowed them to breed in dry places." "Developing young were now bathed in a miniature ocean within the eggs." "The reptiles were on the verge of global domination." "One thing held them back:" "With their skin now water- and airtight breathing became a problem." "Lizards breathe as their chests expand and contract but because of how they walk they often have to hold their breath." "Their sprawling gait, inherited from ancestral fish forces their chests to flex as they walk." "Their lungs can't expand to draw in air and lizards easily become breathless." "The ancestors of the crocodiles, though developed far more stamina." "By standing up on their legs the crocodile line began to walk tall." "No longer swaying from side to side these high-stepping reptiles breathed easily as they strolled relentlessly over the land." "And more than just walking, these reptiles could sprint." "Today, the crocodiles have returned to the water and only rarely trek overland." "But 200 million years ago the small steps their ancestors took led to a giant leap forward." "An athletic line of dinosaurs came to tyrannize the world." "But the future belonged to mammals living quietly in the shadow of the dinosaurs." "65 million years ago the world suffered a massive upheaval." "All the great dinosaurs disappeared." "But many creatures survived, including the mammals." "The earliest were small and furry quite like todays tree shrews." "They had evolved from reptiles whose scales became modified into hair." "Unlike the dinosaurs they survived a cooling of the climate and dinosaur doom led to mammalian triumph." "The mammals also had great strength in their family life." "Mothers reared their young by providing milk." "In the void left by the dinosaurs the mammals stepped into a world of new opportunities." "Many teamed up for survival and came to live in ever bigger families." "This successful but complex way of living led to higher intelligence." "In a dazzling range of forms around the world the mammals have followed in the dinosaurs' footsteps." "They have taken over the roles of powerful predators... resourceful scavengers... and grazers." "And they've ventured into the world's harshest regions." "They still share an ancient need-- water, where life itself was born." "A water hole is a meeting place for many mammals." "Their varied forms reflect both their different ways of life and the long evolutionary war their forebears fought to survive." "The battle to live has molded mammals into a huge variety of shapes and sizes." "Some now need to be wary of others." "Mammals have taken center stage but have the dinosaurs all disappeared?" "Perhaps not entirely." "Birds are really feathered dinosaurs." "One line of small, fast-moving and, most likely, warm-blooded dinosaurs evolved into birds." "Birds have become great successes thanks to their feathers." "As well as insulating them from heat and cold feathers gave birds a further power... a power that made life much harder for their predators." "Flight." "Birds have conquered the air just as mammals have mastered the land." "The vertebrates have come a long way since their lowly origns in the sea." "Evolution's products might seem perfect but the process never ceases." "Where opportunities arise, further change can always occur." "On the Galapagos Islands, a variety of creatures have returned to the cradle of their ancestors-- the sea." "Marine iguaas evolved from land lizards that found the best feeding on the seashore." "Many would have been washed in." "Those that swam survived drowning and today, their descendants dive in to reach the rewards below." "These bizarre reptiles, remolded in form and action by evolution swim daily out to sea." "Here, by harvesting the choicest seaweed they have carved out a unique way of life." "Fish have lured other animals to the sea." "Galapagos commarants evolved from flying birds but their wings have been shrinking in to feeble vestiges." "They're now grounded, but the sea provides their living." "Penguins also gave up flight further back in time and now have flippers where their ancestors had wings." "Sea lions, too, evolved from land creatures and like all sea mammals, they must still breathe air even when asleep in a rock pool." "All these creatures have returned to the water and have once more mastered the ocean." "These mammals and birds have developed the speed and skills to hunt the sea's abundant fish." "In the battle for survival evolution constantly reshapes life to seize opportunities wherever they arise." "Today, a sleek swimming mammal competes for fish with a supreme aerial master." "Sea lion and frigate bird-- winning designs evolved from reptiles and born of the battle for life." "Even at the ends of the earth, life has found a way to triumph." "Wherever animals are found they are molded for survival by the rigors they confront." "King penguins struggle ashore from Antarctic waters." "Conditions here are harsh but vibrant life carpets the frozen land." "Despite all adversities, countless new lives continue the battle for survival." "The young carry the genes of sucessful parents forward through time." "Their lives, and their genes, will be tested to the limits." "Our world is filled with triumphant survivors of evolution's four-billion-year war." "Life's struggle continues to shape everything that lives."