Using footage shot by naturalists all over the world, the film presents the evolution of animal life on earth, beginning with single-celled creatures that existed in the ocean more than a billion years ago and ending with the multitude of animals that exist today. Millions of years after their first appearance in the sea, life forms developed genders, and protective shells, plates or skin. After the development of spines, some creatures evolved into amphibians that became ancestors of land vertebrates. Although frogs, crabs and other creatures made their home on land, reptiles conquered it. For thirty thousand years, dinosaurs reigned, but then came to a mysterious end. The reason for their demise is uncertain, but geologic disturbances, climate change and the unnatural lack of mother love for offspring probably contributed to their downfall. Flooding, an ice age, volcanic fires and earthquakes sealed the fate of the dinosaurs, whose remains sank into the earth. Adaptable creatures such as termites and ants survived, perhaps because of their sophisticated division of labor and social order. As the climate warmed over the passage of time, abundant sun and plant-life provided food for lowly mammals, the next species of animal that came to dominate the earth. However, when the earth froze again, only the adaptable mammals, such as the walrus, survived. Man's appearance on earth is estimated at approximately a million years ago, and his history is intertwined with animals. Throughout history, man deified certain animals, and remnants of these relationships have survived as superstitions and sayings, such as "three wise monkeys," "lucky black cats" of Egypt or the "lucky" rabbit's foot. From the Bible we know that man's first villain was the snake. The Bible, folklore and fantasy all describe animals in stories like Daniel in the lions's den, Little Miss Muffet, and Jonah and the whale, and many animals have been important to human history, such as the horses ridden by Paul Revere and Alexander the Great. The lack of horses led to the fall of the Roman Empire and horses helped settle the new world. Man has learned much from the animals, including how to swim, fly and hunt. Although animals live together peaceably, protected by man, in sanctuaries such as Africa's Krueger National Park, nature has brutal ways of maintaining the status quo in the wild. As shown in the film, a lioness pursues an impala for food, and vultures and hyenas wait for their turn to eat after a kill. Insects, which appeared two hundred fifty million years before man, now outnumber him by 750,000 species. However, nature keeps a balance by making insects food for other insects, birds and carnivorous plants. A struggle between man and beast has always existed, but man is better equipped for that struggle, having conscious reasoning ability, sharp eyes, free moving hands and arms, opposable thumbs, ability to make tools, speech and communication skills and a faculty to walk erect. Because man can imagine, remember and record his acquired knowledge, he is, so far, the highest form of animal life in approximately a million and a half known species of birds, fish, reptiles, insects, mammals, amphibians and micro-creatures. Ten billion animals are domesticated for food, clothes and other byproducts used by man. Some animals are hunted for sport, and some, like the elephant, may be hunted to extinction. A tiger, which is shown stalking an antelope, winds up in a zoo or circus. Animals have provided entertainment for hundreds of years in rodeos and chariot races. Parrots, a chicken and a pig are shown doing tricks they have learned using instincts, adaptability, forethought and capacity to reason, thus proving their ability to think. As shown in the film, normally fierce enemies, such as a fawn, a baby bear and baby mountain lion, befriend each other, when they are not taught to fight. Animals often win in impossible situations. For instance, when a ferret and a cobra face off, the ferret often wins. By kicking sand in its enemy's eyes, kangaroo rats discourage an attacking hela monster. Although a nearsighted sow bug is caught by a trap-door spider, it manages to walk away unharmed. The film concludes with the assertion that man is sovereign over the animal world, but that only man willfully destroys himself. Because man has a soul to help him distinguish right from wrong, the film hopefully suggests that man's reign has just begun and "this is not the end."