HUMAN ORIGINS, personal origins. These two revealing, but often purposely reticent, books uncover the fascinating bones of our present paleoanthropological knowledge and also of their authors' linked individual histories -- without, however, answering a few of the questions that these same disclosures raise. But reading an autobiography is a little like fossil hunting: the untold bits of gossip and the missing lower jaws tug as hard at our curiosity as the items so meticulously excavated for display.

Inevitably, one of the most interesting skeletons unearthed in these autobiographies is that of Louis S.B. Leakey, Mary's husband and Richard's father. Arguably the most successful, and surely the most controversial, paleoanthropologist of this century, Louis died in 1972. No one was more instrumental than he in discovering and then publicizing the strong likeihood that the human species had its earliest origins in Africa. Without his influence, support, and (late in life) occasional jealous opposition, neither his wife nor his son would have forged their own remarkable careers as fossil hunters. Indeed, Mary Leakey divides her life into three parts: "the years with Louis" and distinctive pre-and post-Louis periods, while Richard Leakey calls a chapter at the heart of his narrative "Out of My Father's Shadow."

What picture of the Leakey patriarch emerges from this binocular view? Although the child of missionaries, Louis had a strong streak of the iconoclastic maverick. He was not afraid to defy convention, either in the area of public morality or that of received scientific writ. In England, in the mid- 1930s, to give his first wife grounds for divorce and himself the freedom to wed again, he lived in adultery with the archeologically inclined Mary Douglas Nicol. When the Rhodes Trust gave him funding to do a major study of the Kikuyu tribe in Kenya, he wrote 700,000 words of ethnogaphy between 1937 and 1939 and then refused to cut his manuscript to make it economically feasible to publish. Over the next three decades, at Olduvai Gorge in Tanzania, he and Mary accomplished field work that totally reshaped the family tree of the human species.

As an arthritic sexagenarian, Louis drove himself ruthlessly. To raise money for his digs, he lectured all over the United States -- but tarnished his scientific credibility by claiming to have found evidence of early man in Southern California. Richard's upstart climb to fame alternately bemused and buoyed him, while Mary's successsul independent researches at Olduvai must have underscored for him the fact that he was no longer the indispensable star of the clan. Separated from her from 1968 on, he probably spent more time doing whirlwind PR than meaningful archeology. The heart attack that killed him occured in the London flat of the mother of one of his most famous prot,eg,es, Jane Goodall, renowned for her pioneering work among the wild chimpanzees of the Gombre Stream Preserve in Tanzania.

THE ERRATIC alpha-male behavior of her husband was finally less a puzzle than a sadly comprehensible irritant to Mary. In Disclosing the Past, she attributes their separation to her disagreement with him over the issue of early man in North America. She attributes the frenetic pace of his lecture tours to his need to prove that neither professionally nor personally was he over the hill. Perhaps, too, his women, "some of whom were girls barely out of their teens, who gave him tenderness and affection," acknowledges Mary. "On this I do not wish to dwell. Of course I knew, and of course I minded, and perhaps what I minded most was the deplorably low standard . . . of his choices in some cases." But the decline of Louis Leakey represents the only major melancholy note in a life story that is more often quirkishly doughty and upbeat.

The scientific triumphs of Mary Leakey include the discovery of a Proconsul hominid skull on Rusinga Island in Lake Victoria in 1948, the unearthing of a new hominid species (Australopithecus boisei) at Olduvai in 1958, and the supervision of the team that found three sets of fossilized hominid footprints in a layer of petrified volcanic ash at Laetoli in Tanzania in the late 1970s. These footprints, one of the most dramatic paleoanthropological finds ever made, established that a possible human ancestor was walking upright as long ago as 3.5 million years. They suggest, too, that bipedalism antedates tool making, a matter previously much debated. But these several triumphs are merely notable highlights in a career of undeniable brilliance, and learning that Mary Leakey has a fondness for hard liquor and after-dinner cigars is one of the human bonuses of this welcome book.

Another is her wittily indignant critique of Donald Johanson and Maitland Edey's Lucy: The Beginnings of Humankind (1981), an account of Johanson's field work in Ethiopia's Afar Trangle between 1973 and 1977: "A great deal of verbatim conversation is quoted in the book; some of it even purports to have taken place in my camp at Laetoli . . . But wherever these pseudo-quotations come from the fact that I know so many of them to be inaccurate is bound to throw grave doubt over the rest of the account. To give just one example: I was the only person present to hear what Louis said when I showed him my find of the Zinjanthropus skull, and it certainly was not, as needlessly quoted in Lucy, 'Nothing but a . . . robust australopithecine.'" Pointedly, Mary's book eschews dialogue and makes extremely sparing use of direct quotation.

LIKE MOTHER, like son: Richard's One Life adopts the same strategy. Nevertheless, it manages to convey a sense of novelistic high adventure absent from Mary's autobiography, probably because he relates such anecdotes as his embarrassing self-imprisonment in a trap set out for a leopard, a near-disastrous attack by a crocodile on the Omo River in Ethiopia, and various other suspenseful encounters with snakes, camels, armed bandits, and his own "long-suffering" father. Moreover, the final two chapters turn on the chronic kidney disease that almost killed him at age 35. Indeed, Richard wrote his book while hooked to a dialysis machine waiting out the conclusion of an election in Kenya that would permit his younger brother Philip to fly to London to donate a kidney. His frank confession that for 10 years he and Philip had not been on good terms heightens the drama of their reunion, as does Philip's matter-of-fact disclosure that either before or after the crucial transplant operation his political foes might try to assassinate him. And Richard may be in danger because he and Philip look so much alike!

One Life seems a more forthright document then Disclosing the Past -- but this may be true only beacuse Mary employs irony or indirection where Richard relies on self-effacing humor and disarming admissions of bad judgment or unfortunate lapses of tact. He freely chronicles his struggle to obtain scientific credibility without an academic degree, his unpopular efforts to Kenyanize the National Museum in Nairobi, and his unbending support of an erroneous date for an important fossil-bearing layer at his Koobi Fora digs in northern Kenya. (In her book, Mary reports that after she expressed her doubts about Richard's preferred date, he was decidedly cool toward her until the issue was clearly resolved.) On one question, however, the son is undeniably more forthcoming than his mother, who, curiously, altogether ignores it. That question is the matter of religious faith.

Evolutionary research has many implications for those who interpret their Bibles literally. Although Richard sees no conflict between faith and the scientific wiew of the world, his own credo is nontheistic: "I myself do not believe in a god who has or had a human form and to whom I owe my existance. I believe it is man who created God in his image and not the other way round; also I see no reason to believe in life after death." He then acknowledges that the mystery of life -- of the "spirit" animating living things -- continues to nag at him; he suggests that science may ultimately solve this riddle.

Mary, raised a Catholic, mentions a brief contretemps with creationists in Arkansas during a 1981-82 lecture tour, but otherwise avoids discussing the metaphysical ramifications of her researches. Does she assune them self-evident? Has she made a conscious decision not to step on the toes of her religious friends and supporters? Or, the most dismaying of these three alternatives, does the question simply fail to interest her? "Basically, I have been impelled by curiosity," Mary writes toward the end of her book, but Disclosing the Past provides no evidence that her curiosity gets past Who, What, Where, and When . . . to Why.

Still, four out of five isn't bad, and the Leakey family has probably done more to prompt debate about human origins than anyone since Charles Darwin himself.