Interfacing in the Ice Age : THE PLAINS OF PASSAGE<i> By Jean M. Auel (Crown: $24.95; 752 pp.)</i> ; THE ANIMAL WIFE<i> By Elizabeth Marshall Thomas (Houghton Mifflin/Peter Davison: $19.95; 289 pp.) </i>

“Judge the goodness of a book by the energy of the punches it has given you,” wrote Gustave Flaubert, author of “Madame Bovary.” According to him, “the greatest characteristic of genius is, above all, force.”

Two new novels about prehistoric hunter-gatherers--”The Plains of Passage” by Jean M. Auel and Elizabeth Marshall Thomas’ “The Animal Wife”--both exemplify the kind of narrative power that Flaubert equated with virtuosity. Nevertheless, these are vastly different renditions of broadly similar themes.

Auel, a superlative raconteur. has crafted a consistently engaging adventure story with a solid historical underpinning. Set in Ice- Age Europe, it also incorporates numerous touches commonly found in commercial fiction: lusty, protracted sex scenes (the heroine’s sweetly ingenuous euphemism for intercourse is “pleasures”); natural and man-made adversity; and a suspenseful “Perils of Pauline” atmosphere in which the protagonists must grapple with unanticipated, potentially lethal hazards ranging from mammoths to mudslides.

Anthropologist Elizabeth Marshal Thomas approaches her material in a more detached, meditative manner than does Auel. Somber verisimilitude supersedes dramatic embellishment in “The Animal Wife,” which concerns the daily exigencies of survival in Siberia 20,000 years ago.

Simply put, what Thomas actually presents is a nearly 300-page “snapshot” of Paleolithic life. Filled with evocative descriptions of an environment that offers sustenance as well as daunting hardships, this tale features the interrelated members of several hunting groups. As narrated by an earnest, unworldly young man named Kori, we see these people gamely struggling to retain their fragile unity even while friction between the sexes jeopardizes it.

The last book in Jean Auel’s multivolume “Earth’s Children” series was “The Mammoth Hunters” (1985). In “The Plains of Passage,” she brings back Jondalar and Ayla, itinerant lovers who now attempt to traverse a continent in order to join Jondalar’s kin, the Zelandonii. Three personal qualities help them to withstand this seemingly interminable trek: ingenuity, fortitude and mutual devotion.

Once again, Ayla is depicted as possessing “knowledge beyond the ken of ordinary people.” This dazzlingly innovative 18-year-old outshines everyone around her, including the able Jondalar. Clearly blessed with a more sophisticated intelligence than her peers, versatile Ayla can sew, cook delectable meals, utilize the medicinal properties of certain vegetation, aid the sick and instantly start a fire merely by rubbing iron pyrite with a piece of flint.

However, Ayla’s most wondrous feat involves two horses and a wolf. While her Ice-Age contemporaries slaughter such animals for their hides or to be consumed as food, she chooses to tame the beasts, transforming them into benign companions. Strangers whom Ayla and Jondalar meet along the way are inevitably transfixed--and highly alarmed--at the bizarre sight of humans astride horses, accompanied by an obedient wolf.

Ayla’s eagerness to demonstrate to these people that they can trust creatures whom they customarily dislike illustrates a pivotal message conveyed by “The Plains of Passage”--that good will, open-mindedness, toleration and patience are almost always preferable to unthinking hostility. Consequently, those with selfish, belligerent attitudes who display no respect for the rights of others or the sanctity of life are the villains of this novel, villains whom Jondalar and Ayla jointly vanquish.

A corollary subplot of the book concerns the callous mistreatment of women by men, a theme dealt with far more extensively in “The Animal Wife.” As Auel shows, females make vulnerable targets for the unchecked lust and violence of aggressors. In her view, though, even victims of barbarism can be physically and spiritually reinvigorated via salutary doses of love.

Misogyny surfaces repeatedly in “The Animal Wife,” which Elizabeth Marshall Thomas calls “a companion piece”to her 1987 novel, “Reindeer Moon.” The narrator, Kori, declares, “My story is the story of women.” With electrifying clarity, Thomas soon reveals that the abuse of women will figure prominently in his saga.

The characters in “The Animal Wife” confront the same conditions that Jondalar and Ayla face. They require food and shelter, cope with harsh weather and constantly need to outwit predators. Since these tasks are better accomplished through collective action than individual effort, Kori’s relatives all try to cooperate. Regrettably, genuine harmony isn’t sustainable due to the men’s overt chauvinism and their conception of women as chattel.

“Marry as many as you can,” Kori’s father, Swift the shaman, cavalierly instructs his son. Virile and authoritative, Swift--like other men--puts high value upon wedding often, as well as advantageously. His latest bride, Pinesinger, is a seductive young woman whose past contains an eyebrow-raising entanglement. Unbeknownst to Swift, she and Kori have had a sexual liaison, and Kori’s now forbidden yearning for Pinesinger hasn’t abated.

With all the fiery bravado of youth, he sets out to claim the emblems of swaggering manhood: a wife, prowess as a hunter and true camaraderie with adults. Pinesinger is beyond his grasp, so Kori devises alternative ways to flaunt his maturity. During one unforgettably graphic episode, he, Swift and Swift’s brothers kill a bison, then gulp down its blood in a grotesque ritual of male solidarity. “When my turn came,” Kori rhapsodizes, “a rush of strength and heat from the fresh blood filled my body.”

Eventually, Kori notices a strange new woman whom he decides to nab. Assisted by his uncle, Andriki, he punches her, hoists her inert body over one shoulder and transports her to his people’s lodge. Like an ecstatic child with a delightful plaything, Kori proudly names this acquisition Muskrat, and thrusts her amongst his startled folk. They immediately bristle, fearing that she might have relatives who will retrieve her by force.

In addition, Muskrat suffers ostracism because she is different. Her language sounds peculiar; she has lice, and out of ignorance, she eats without sharing, a trait that affronts others. Kori, thinking mainly of amorous gratification and not of Muskrat’s feelings, does little to integrate her with the group.

She and Pinesinger finally stalk out of the camp together, livid about the numerous humiliations they have received from their mates. When tragedy occurs as a direct result of their departure, it seems virtually preordained. “Everyone was unhappy, but it was to be,” Kori fatalistically concludes.

Both Auel and Thomas excel at portraying complex social interactions, along with the richly dynamic milieu of a long-ago epoch. Beyond some obvious similarities in content, however, “The Plains of Passage” and “The Animal Wife” have little in common.

Auel’s book consists of pure entertainment at its sublime, wholly exhilarating, best. Brimming with thrills, emotionally charged confrontations and moments of high passion, the novel resembles a fairy tale in that every impending catastrophe is averted, thus allowing the saintly hero and heroine to flourish. Such contrivances in “The Plains of Passage” are forgivable, for Jondalar and Ayla enchant us so completely that we revel in their charmed destinies. By coaxing readers to suspend disbelief, Auel beckons them into her comforting fantasy world of ideal resolutions and triumphant valor.

“The Animal Wife” relies upon hard-edged authenticity for its impact. The wanton misconduct of various characters is eerily modern and thoroughly repugnant, yet Thomas refrains from tossing in any lighthearted frills to make it more palatable. Instead, she focuses on the grave reverberations of certain acts, such as shunning a hapless outsider and blithely degrading women.

This novel imparts no gleeful reassurances about decency inevitably prevailing over injustice. Only one chilling message emanates from Elizabeth Marshall Thomas’ sleek prose: Human nature has improved very little over thousands of years.