A friend who was asked to write a blurb for “Participant Observer” had just finished reading Joyce’s “Portrait of the Artist as a Young Man,” and she was tempted to compare Robin Fox’s book very favorably with Joyce’s. She thought that might seem improbable, however, and so chose other words. But the comparison is apt, especially in the way both authors treat the subject of religion, belief, personal integrity, and swirling eddies of doubt about granite assertions of faith.

For Joyce the sanction for godlessness and the subsequently unavoidable misbehavior was the steamily elegant threat of Dantean hell. For Mr. Fox the penalty is the necessary acceptance of human irrationality, fantasy, and a strange realm of consensual unreality. Reluctantly, he has embraced the explanatory force of the illogical. Perhaps it was this that drove him to biology in the first pace.

I’ve known Mr. Fox for 40 years. We wrote a book together in 1971, “The Imperial Animal.” Since 1969, we’ve both been members of the Department of Anthropology at Rutgers University. For decades we’ve been stubborn warriors in the effort to align the natural and social sciences. Our consistent question: Does the formal separation in the halls of learning between the two suggest that social behavior is somehow not natural? Of course it is. How and why and when is the issue, and it’s a substantial one.

In 1965, I spent three days talking in Mr. Fox’s office at the London School of Economics. What was a very exciting conversation resulted in a nine-page paper published in the Journal of the Royal Anthropological Institute. With punctilious modesty we called it nothing less than “The Zoological Perspective in Social Science,” and both its hubris and argument attracted lively attention. We were co-research directors of the Harry Frank Guggenheim Foundation for a dozen years, and I figure somewhat in “Participant” as a factor in Mr. Fox’s life.

As a person, Mr. Fox can be hilarious, finds it impossible to be mean, and possesses the occasionally irritating capacity to recall and try to sing all of Gilbert and Sullivan. He is also one of the world’s experts on the anthropology of kinship, and his 1967 “Kinship and Marriage” is in print in umpteen languages and double-digit editions. He has conducted field research among the Hopi of the American Southwest and the Celtic fishermen of Tory Island.

“Participant” tells of his threadbare but doughty youth during World War II in Bradford, in northern England. As pointedly as Kingsley Amis but without the bitterness of John Osborne, he describes his puzzled but implacable mastery of grammar school, his glorious First in Sociology at the London School of Economics (one of two awarded that year), and a subsequent series of unplanned accomplishments in the Department of Social Relations at Harvard and the LSE. Mr. Fox received a Ph.D there and in 1967 became the youngest person ever to be promoted to the particular English status Professor, which then was near-Princely.

There is scarcely a misplaced word or unconvincing sentence throughout the 575 pages of this memoir, which both an intellectual adventure story and a coolly wry self-analysis of a person encountering, with surprised innocence, varied turbulences ranging from ill babies to World War II to the discovery of DNA to the relentless busyness of well-meaning American concernocrats saving the world from the Offices of Deans. Even a learned description of the complexities of Pueblo linguistic analysis delivers a fair lesson in the power of traditional anthropology.

The book follows three themes. The first is the room-at-the-top-or-club-chair-in-the-Senior-Common-Room adventure, with all the complex reflection on English society that subject can generate – the eager young Englishman makes guilelessly good. The second is a comedic but warm exploration of the meaning of America as an occupational challenge and a fruitily exotic place to live and work – he and his family first inhabited Princeton, where they were proudly told there was no synagogue but instead a “Jewish Center.” The third and most central is the importance of challenging regnant assumptions in social science not only because they may be wrong but because they are too readily employed by makers of social policy, who fail to understand the species whose zoo they are managing.

This adventure is embellished with tales of the rollicking oddity of his human relations with spiky and cortically adroit characters ranging from Isaiah Berlin to E.O. Wilson to Richard Rorty to Ashley Montagu to Robert Ardrey to Hugh Trevor- Roper to Jimmy Dolittle to Senators Fulbright and Moynihan. The man’s memory is frighteningly capacious – it is never agreeable to relearn episodes of one’s own life from another person’s book, even if they’re funny.

But the book is a complex and responsible account of international intellectual life during the decades it covers. This is important because, as the lessons of genomic and paleontological research continue to establish the facts of human evolution and biology, they only seem to provoke more noisy debate.

There is ever-growing certainty about the vast arc of evolutionary time: Daily newspapers regularly report on discoveries about the intricate complexity of bodily operation. Yet there are ever more zealously disputed by well-funded creationists, who confidently attribute a godly origin for life as we know it but take a lunch break when it’s time to ponder the origin of gods as they describe them. They have been joined in unacknowledged alliance by the postmodern culturologists, for whom even obvious sex differences are an artifact of coercive magazines and cunning patriarchs (yet who have embarrassingly failed to attend to reversing the five- to eight-year female advantage in longevity).

At last these folk have begun to stimulate the oxygenated ridicule their post-empiricism deserves. Nevertheless, they have largely appropriated the humanities and much social science in contemporary universities, and it will be many wearying years before their fashionable influence ebbs. Meanwhile, the cool thoughtfulness of someone like Mr. Fox who is affably obedient to the Law of Parsimony, remains a cultural resource – not only for scientific reasons but for literary ones.

Which takes us back to James Joyce and the issue of belief. Joyce was fortunate as a writer. The miseries his church encouraged him to expect because of his normal banal fecklessness were fabulous and high-toned colorful – the Roman Catholic Church instantly upgrades its antagonists. Mr. Fox had no such advantage. Nevertheless, we’re in luck with his exacting and accomplished analysis of his fall from Official Grace and what this grace business was in the first place. It’s funny, too, and you meet some interesting people. Even the ones you already know begin to look better.

Mr. Tiger is Darwin Professor of Anthropology at Rutgers University.