In 1995 I traveled to the University of California, Santa Barbara, for the annual meeting of the Human Behavior and Evolution Society, which turned out to be a pep rally for psychologists, anthropologists and others who view humanity through the lens of evolutionary theory. Attendees heard Darwinian takes on lust, love, infidelity, status-seeking, mental illness, violence, patriotism, politics, economics and religion, as well as keynote addresses from such luminaries as Richard Dawkins and Steven Pinker.

The most influential thinker there, arguably, was a scruffily bearded fellow, wearing sunglasses and a knitted cap, who never gave a talk. He lurked around the margins of the conference; at one point I spotted him puffing a joint outside a meeting hall. This, at any rate, is how I remember Robert Trivers, although as he points out in “The Folly of Fools,” memory often tricks us. He also confesses to being a pothead, so I’m pretty sure my recollection is accurate.

As a Harvard graduate student in the 1970s, Trivers wrote a handful of papers showing how our genes’ relentless drive to self-replicate underpins even our most apparently magnanimous impulses. According to his theory of reciprocal altruism, we occasionally act kindly toward strangers because our ancestors — over time and in the aggregate — received a quid pro quo benefit from acts of generosity. In other papers, Trivers proposed that families roil with conflict because parents share no genes with each other and only half of their genes with children, who unless they are identical twins also have divergent genetic interests.

These concepts were popularized by others, notably Edward O. Wilson in “Sociobiology,” Dawkins in “The Selfish Gene” and Pinker in “How the Mind Works.” All have credited Trivers, whom Pinker has called “an underappreciated genius, and one of history’s greatest thinkers in the analysis of behavior and emotion.” If Trivers is not better known, that may be because he has struggled with bipolar disorder since his youth. He is also, by his own admission, an irascible anti-authoritarian, whose sharp tongue often gets him into trouble. He left Harvard in the late 1970s, eventually ending up at Rutgers. He also has a home in Jamaica.