By Elizabeth Marshall Thomas

Houghton Mifflin. 289 pp. $19.95

We want to believe that if we track the footprints of Homo sapiens, no matter how far back they lead, we will encounter a recognizable man. The setting will have changed. There will be caves and campfires instead of condos and central heating, and the wearers of furs will be safe from pickets marching in protest. But in that primitive place we will find our fellow man, susceptible to the loves and fears that haunt us still.

It is this premise that lies behind the popularity of such books as Jean Auel's "The Clan of the Cave Bear" and Elizabeth Marshall Thomas's "Reindeer Moon," set, like her present novel "The Animal Wife," in Siberia 20,000 years ago. Her people are a small tribe of hunter-gatherers living in an intricate connection of kinships and in crucial closeness to the skin of the earth. They command their place by cunning, not by strength, since man and mammoth are not created equal.

Reading the world around them the way we read the daily paper, they use their knowledge of signs and seasons to store food and to protect themselves from predators. Their strength comes from the group, with each member helping so that all will survive. People who live together in a small, dark cave through the long winter cannot afford to destroy their cohesion with quarrels.

Kori is new to the group. Raised with his mother's people, he has now joined his father's clan. A boy on the edge of manhood, he yearns for his father's praise. He also yearns for his father's new wife, Pinesinger, and though his desire is briefly appeased when he learns he himself is to be given a wife, Frogga, his happiness is short-lived.

Arriving at his father's camp, he sees "a little girl who had just learned to walk, which she did rather badly, as if she were about to fall forward with each wobbling step. A charm against diarrhea was tied around her belly on a string -- her only clothing. She drooled and her nose ran... . Maral ... held her up, and said, 'Frogga!' "

The marriage is a way of strengthening kinship, but to Kori it is an insult to be given a baby wife. When he sees a strange woman swimming alone in a pond, he seizes her, stealing her from her people and making her his own. Muskrat, he calls her, and her foreign ways and her foreign tongue make him treat her as a possession rather than a person. Even though he is warned that his hasty act has put the group in danger, he swaggers with pride at his catch. "All by myself I had taken this woman whose bare feet stepped neatly in the tracks. ... As in the very best of hunting, I had seen at once what should be done and I had acted quickly and bravely."

Twenty thousand years ago, and Kori is behaving like a typical teenager, testing his limits, challenging his parents, driven to folly by his raging hormones. Kori is in a car where there is no designated driver. He is also in a world where careless acts have fatal consequences.

Thomas, an anthropologist, has used information that she collected while studying the African Bushmen to show how a primitive tribe of hunter-gatherers lives. Her Siberia is not the icy wasteland we know today, but a colder version of the African savanna, and the methods her people use to hunt and to cook are little different from those used by primitive tribes through all the ages that have layered themselves on the land.

Thomas reasons, probably rightly, that new inventions are what changed the traditional ways and that the life lived by the Bushmen would be recognizable to our early ancestors. One of the things that perplexes Kori is how Muskrat's people could have killed a man with a tiny little spear. The bow and arrow as a weapon is known to Muskrat's clan but is still strange to Kori's.

It is neither the plot, which is simple, nor the characters, who are conventional stereotypes transported back in time, that give strength to "The Animal Wife." What makes it worth reading is the convincing way Thomas is able to re-create lives lived in a long-gone culture, making the reader feel the cares and pleasures of a people who, with their fellow animals, walked warily through a world where those who were not watchful did not survive.

The reviewer writes frequently about contemporary fiction for Book World.