Two obituaries of Robert Trivers

March 25, 2026 • 9:30 am

Although I did call attention to the death of Robert Trivers, age 83, on March 12, and I knew him slightly, I did not have the chops to summarize his many contributions, nor did I know him that well (we overlapped at Harvard). Fortunately, Steve Pinker has produced an absolutely terrific bio of Trivers at Quillette: a piece that summarizes the many contributions to evolutionary biology made as a young man, and then his many eccentricities, quirks and obnoxious or even illegal behaviors that made Trivers somewhat of an apostate. He was a complex and fascinating person, and I hope someone will write his biography (he did write an autobiography, Wild Life: Adventures of an Evolutioanry Biologist, but deserves a thorough, disinterested, and Cobb-like treatment).

Steve’s obituary, which you can access by clicking on the screenshot below or seeing it archived here, is roughly in three sections: Trivers’s contributions to the field, an analysis of why they came so young and so fast (he did almost nothing during the last five decades of his life), and a description of his complex personality and behavior. It’s long for an obituary, but Trivers deserves long, and of course Pinker summarizes his life eloquently.

Trivers’s major contributions as Steve outlines them (Steve’s words are indented, bold headings are mine):

. . . two weeks after the death of Robert Trivers, one of the greatest evolutionary biologists since Charles Darwin, not a single major news source has noticed his passing. This despite Trivers’s singular accomplishment of showing how the endlessly fascinating complexities of human relations are grounded in the wellsprings of complex life. And despite the fact that the man’s life was itself an object of fascination. Trivers was no ordinary academic. He was privileged in upbringing but louche in lifestyle, personally endearing but at times obstreperous and irresponsible, otherworldly brilliant but forehead-slappingly foolish.

I still can’t see an obituary for Trivers in either the NYT or the Washington Post. That lacuna is shameful. On to his contributions (

Contributions:

Parent-offspring conflict:

Trivers’s innovation was to show how the partial overlap of genetic interests between individuals should put them in a partial conflict of psychological interest. The key resource is parental investment: the time, energy, and risk devoted to the fitness of a child. Parents have to apportion their investment across all their children, each equally valuable (all else the same). But although parents share half their genes with each child, the child shares all its genes with itself, so its interest in its own welfare will exceed that of its parents. What the parent tacitly wants—half for Jack, half for Jill—is not what Jack and Jill each want: two thirds for the self, one third for the sib. Trivers called the predicamentparent-offspring conflict.

Sex differences in parental investment:

Trivers explained the contrast by noting that in most species the minimal parental investments of males and females differ. Males can get away with a few seconds of copulation; females are on the hook for metabolically expensive egg-laying or pregnancy, and in mammals for years of nursing. The difference translates into differences in their ultimate evolutionary interests: males, but not females, can multiply their reproductive output with multiple partners. Darwin’s contrast can then be explained by simple market forces. And in species where the males invest more than the minimum (by feeding, protecting, or teaching their offspring), males are more vulnerable than females to infidelity (since they may be investing in another male’s child) and females are more vulnerable to desertion (since they may bear the costs of rearing their mutual offspring alone).

Reciprocal altruism:

In another landmark, Trivers turned to relations among people who are not bound by blood. No one doubts that humans, more than any other species, make sacrifices for nonrelatives. But Trivers recoiled from the romantic notion that people are by nature indiscriminately communal and generous. It’s not true to life, nor is it expected: in evolution as in baseball, nice guys finish last. Instead, he noted, nature provides opportunities for a more discerning form of altruism in the positive-sum exchange of benefits. One animal can help another by grooming, feeding, protecting, or backing him, and is helped in turn when the needs reverse. Everybody wins.

Trivers called it reciprocal altruism, and noted that it can evolve only in a narrow envelope of circumstances.

This to me is Trivers’s most important contribution, explaining not only why we sacrifice for unrelated people, but also making testable (and largely verified) predictions about human behavior, including morality.  Now that humans no longer live in small groups of acquainted people—conditions under which reciprocal altruism presumably evolved—we can expect some of those behaviors to disappear, but civilization is a mere eyeblink compared to the long, long period in which the conditions were right for the evolution of altruism (and deceit; see below).

Asymmetries in human relationships:

. . . in a passage that even fewer readers noticed, Trivers anticipated a major phenomenon later studied in the guise of “partner choice.” Though it pays both sides in a reciprocal partnership to trade favours as long as each one gains more than he loses, people differ in how much advantage they’ll try to squeeze out of an exchange while leaving it just profitable enough for the partner that he won’t walk away. That’s why not everyone evolves into a rapacious scalper: potential partners can shun them, preferring to deal with someone who offers more generous terms. Just as a store with a reputation for fair prices and good service can attract a loyal clientele and earn a bigger profit in the long run than a store that tries to wring every cent out of its customers only to drive them away, a person who is inherently generous can be a more attractive friend, ally, or teammate than one who dribbles out favours only to the extent he expects them to be repaid with a bonus. The advantage in attracting good partners makes up for the disadvantage in forgoing the biggest profit in each transaction.

And since humans are language users—indeed, reciprocity may be a big reason language evolved—any tendency of an individual to reciprocate or cheat, lavish or stint, does not have to be witnessed firsthand but can be passed through the grapevine. This leads to an interest in the reputation of others, and a concern with one’s own reputation.

The evolutionary significance of deceit and self-deception:

Trivers’s fifth blockbuster was laid out not in an academic paper but in a pair of sentences in his foreword to The Selfish Gene:

If (as Dawkins argues) deceit is fundamental to animal communication, then there must be strong selection to spot deception and this ought, in turn, to select for a degree of self-deception, rendering some facts and motives unconscious so as not to betray—by the subtle signs of self-knowledge—the deception being practiced. Thus, the conventional view that natural selection favors nervous systems which produce ever more accurate images of the world must be a very naïve view of mental evolution.

We lie to ourselves the better to lie to others, protecting compromising private knowledge from emotional tells or factual contradictions (as in the Yiddish saying, “A liar must have a good memory.”) In his book Social Evolution(1985), Trivers muses on how this can play out:

Consider an argument between two closely bound people, say, husband and wife. Both parties believe that one is an altruist of long standing, relatively pure in motive, and much abused, while the other is characterized by a pattern of selfishness spread over hundreds of incidents. They only disagree over who is altruistic and who selfish.

The theory of self-deception is deeper (and more enigmatic) than the commonplace that people’s views of themselves are mistuned in their favour. The self, Trivers implied, is divided: one part, seamless with the rest of consciousness, mounts a self-serving PR campaign; another, unconscious but objective, prevents the person from getting dangerously out of touch with reality.

Trivers wrote an entire book about this, a book that he intended to co-author with the (in)famous Huey Newton, a founder of the Black Panthers (Newton was murdered before it could be written): The Folly of Fools: the Logic of Deceit and Self-Deception in Human Life. It’s an uneven book, larded with bizarre personal anecdotes, but it also contains a lot of intriguing food for thought. In other words, it’s pure Trivers.

Why did Trivers make these contributions?  A few of Steve’s thoughts:

. . . Trivers revelled in explaining the contradictions of the human condition, and he himself was a mess of them. Foremost is how he revolutionised the human sciences in a fusillade of ideas he had between the ages of 28 and 33 (I didn’t even mention a sixth one, on how parents should invest in sons versus daughters). But then he did nothing comparable for fifty years. He wrote some good books, but they were reviews of his and others’ contributions, breaking little new ground. How do we explain this shooting star?

Part of the answer is that, as with all intellectual revolutions, the right mind found itself in the right era. In 1971 the gene’s-eye view of evolution was new and counterintuitive, as it remains to this day. People, including scientists, project their moral and political convictions onto the things they study, and the ideal that we should love our neighbours, act for the good of the group, and strive for social betterment is easy to read into nature, even if it flouts the logic of natural selection. And whenever the word “gene” comes up, readers get distracted by hallucinations such as that humans are robots controlled by their genes, that each of their traits is determined by a single gene, that they may be morally excused for selfishness, that they try to have as many babies as possible, that they are impervious to culture, and other non sequiturs.

The young Trivers, mentored at Harvard by the biologists William Drury and Ernst Mayr, immediately grasped the new way of looking at evolution, and never got hung up by these misconceptions. A jaundiced view of animals, not excluding Homo sapiens, came naturally to his rebellious temperament, and many puzzles he observed in his field work (including on ants, lizards, gulls, songbirds, caribou, baboons, and chimps) fell into place when he considered their reproductive interests from their viewpoints.

. . . In the early 1970s, then, Trivers was standing on the shoulders of giants, looking with a gimlet eye over a rich array of poorly explained animal behaviour (not excluding humans, since he had recently binged on novels). In this virgin landscape, the implications of the overlapping conflicts of genetic interests were waiting to be discovered, foreshadowed in scattered passages from Hamilton and Williams. Someone had to see them first, and Trivers was there.

. . . But Trivers rapidly spotted what everyone else missed, and still misses, together with the less biologically obvious concept of self-deception, so there must be another piece to the puzzle. During his junior year at Harvard, Trivers suffered two weeks of mania and then a breakdown that hospitalised him for two months. Bipolar disorder afflicted him throughout his life. I can’t help but wonder whether Trivers’s fecund period was driven by episodes of hypomania, when ideas surge and insights suddenly emerge through clouds of bafflement.

I had never thought of that, though Trivers made no secret of his diagnosis.  Finally, a bit about his behavior:

Though his upbringing was patrician and cosmopolitan (son of a poet and a diplomat, schooled in Europe and then Andover and Harvard), he was afflicted with a strong nostalgie de la boue. This contributed to his adoption of Jamaica, originally the site of his research on lizards, as a second home. Trivers’s life in Jamaica was filled with boozing, brawling, whoring, and of course toking, together with a stint in jail and a narrow escape from death during an armed robbery. His memoir Wild Lifeis peppered with homicidal fantasies and expressions of admiration for thuggish vigilantes, including Huey Newton, co-founder of the radical Black Panther Party. Trivers befriended Newton, made him godfather of his daughter, coauthored a paper with him on the role of self-deception in a fatal plane crash, and became a white Black Panther himself before Newton ushered him out of the organisation for his own safety.

. . . But Trivers’s neuroatypicality shaded into eccentricity and downright boorishness. He might try to drop off a passenger without stopping the car, or miscount the number of dinner guests and force two of them to share a chair. He repaid the colleagues who offered him professional lifelines at their universities with truancy, belligerence, and gross inappropriateness (greeting female students in his underwear when they had been sent to his apartment to fetch him to a late lecture; requesting that straitlaced academic hosts supply him with cannabis). His violent musings could make acquaintances genuinely fear for their safety. His last graduate student, Robert Lynch, spoke for many when he ended his affectionate obituary, “I’ll miss you, Robert. You asshole.”

. . . As for himself, Trivers liked to poke fun at some of his eccentricities and indignities. But he never squarely faced his record of betrayals, hurts, and squandered talent. All this is exactly what Trivers’s greatest theoretical brainchild would predict.

That “greatest theoretical brainchild” must be self-deception, of course, but I think that was perhaps the least important of his contributions.

Trivers’s had an erratic life, but also a rewarding one and a tumultuous ones. It makes me want to paraphrase Nagel: “What was it like to be Robert Trivers?”

There is also a shorter obituary in The Times of London, which you can see by clicking below or reading it archived here. Although author Finkelstein is not a biologist, he does a pretty good job summing up Trivers’s contributions, though he concentrates too much on the deceit and self-deception part, seeing it mirrored in modern politicians like Donald Trump and Liz Truss. If you want a short read it is okay, but given the choice, you should read the longer Pinker obituary. It will also teach you a lot about modern evolutionary psychology—known as “sociobiology” when Trivers and I overlapped at Harvard.

10 thoughts on “Two obituaries of Robert Trivers

  1. Regarding altruism :

    A good practical test :

    it sounds corny, but I think it’s true : make something – like a dish you enjoy – and give it as a gift to someone you appreciate.

    What happens in that experience?

    Can this program be run with someone you neutrally do not appreciate or even disapprove of?

    It’s for the individual to find out. IMHO it’s win-win.

    Even if they throw the food out!

    Repeat as necessary.

  2. I was very aware of Trivers during graduate school and throughout my early career, and I read a number of his papers. (I never met him.) Pinker’s summary of his contributions reminds me how creative Trivers was. He made so many long-standing problems simply go away.

    How could altruism have evolved, as it is surely not in the altruist’s interest? His answer: It didn’t. Altruism is an illusion. The purported altruist isn’t committing self-harm at all. He’s anticipating a deferred benefit that justifies the original “cost.” So clever! I always thought that Trivers was super important in that he was able to tie up many of natural selection’s loose ends.

    I had no idea that he made few contributions over the last 50 years if his life, nor did I know about his personality defects. He must have been a tortured soul.

  3. I am friends with three psychologists and none of them have heard of Bob Trivers. Or Bill Hamilton.

    This would be like a football (soccer) coach never hearing about Rinus Michaels, Johan Cruyff, and Total Football.

    When Dawkins wrote TSG 50 years ago, he commented on the fact that the social sciences seem to have completely ignored Darwin. Theoretical frameworks for human behavior and mental illness seemed to have no correspondence with mechanics of natural and sexual selection.

    It seems that 50 years later…not much has changed.

  4. I was just giving a lecture about kin selection and reciprocal altruism in my evolution class. I did not really understand the thing about self-deception, so I googled it and got an AI summary that helped me to wrap my head around it better.
    That does seem like another mighty clever idea from this mad genius.

    It does remind me of another behavior we see in animals (and humans), where we distract or groom themselves as a way to relieve stress. These too seem like instances where there is selection for self-care.

    1. Everything in that Trivers musing is sincerely believed trans-sexual (MtF) mainstream ideology. I don’t even want to call it propaganda.

      “Transwomen” even on fastidiously censored YouTube insist that self-claimed heterosexual men find them attractive (commercially at least) for precisely the reasons that Trivers alludes to. This could jibe with his self-deception hypothesis as a gay-rights advocate that for homophobic men, sex with “transwomen” could be a plausibly deniable outlet for their homosexuality. (Trivers might not have been aware that an estrogenized man doesn’t have much in the way of a working “cock” and may not be able to reach “organism” [sic]. Estrogen is more than just adult castration. They are happy to tell this to the world, btw.)

      Trivers gives FtM “transmen” short shrift and so will I, for reasons of word count.

      The allusion at the end to three-year olds is not pedophilia. Rather, it is just what parents are encouraged to do: to “recognize” that Jason is not really a boy and to socially transition him to be a girl. Not with hormones at that age, no, but be ready with puberty blockers at Tanner 2 to keep him a beautiful and sexually immature Peter Pan forever. If he goes on to estrogen, he’ll never do adult things like have orgasm or father children. What Trivers was imagining would be in it for him as a groomer or a predator we’ll have to leave to our imagination. But even the mainstream trans activists argue that the point of doing this is to make it easier for these arrested adolescent boys to pass as pliant women. And predators and customers know that.

      Trivers’s letter to Epstein certainly reflects the trans movement darkly but it is hardly a novel reflection. We transphobes have been saying this all along just not with the same gleeful fascination. What it does for his legacy and reputation I can’t say, because I don’t know enough about him otherwise. I just don’t see the smoking gun for pedophilia that the X poster did. (That wasn’t Epstein’s bag, either.)

  5. Thanks for that. Pinker is always excellent, Trivers deserves a cool obit.
    To channel Tony Soprano: “In this house, Robert Trivers is a hero. End of story!”

    I won’t even address the insane Epsteinology herein b/c the entire moral panic is too stupid for my time. Trivers’ “contribution” to that is no more than de minimus correspondence, prob pushed into (like Pinker, Kraus, etc.) by a greedy dean looking for more donations. More use arguing pizzagate or Q anon. (sigh)

    D.A.
    NYC

  6. I started graduate study in 1980. Trivers’s ideas were central to what my mentors were hoping to get me to understand about the discipline, but I don’t think that I ever knew the name. Eventually, I drifted into bacteriology, where those ideas seemed not to be particularly relevant.

    Pinker links to a substack obituary from Robert Lynch, one of Trivers’s students, with the great line

    “Genius” is one of the most overused words in the language, with “asshole” not far behind, and I have known few people who truly deserved either label. Robert deserved both.

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