Robert Ludlow Trivers (; February 19, 1943 – March 12, 2026) was an American evolutionary biologist and sociobiologist who profoundly influenced both fields. Trivers proposed the theories of reciprocal altruism (1971), parental investment (1972), facultative sex ratio determination (1973), and parent–offspring conflict (1974). He has also contributed by explaining self-deception as an adaptive evolutionary strategy (first described in 1976) and discussing intragenomic conflict. Growing up in a diplomatic household, Robert Trivers attended schools in Berlin, Copenhagen and Washington D.C, before attending Phillips Academy in Massachusetts and going on to study American History at Harvard.
Trivers was open about his diagnosis of bipolar disorder, which was first misdiagnosed as schizophrenia Trivers and Newton became close friends: Newton was godfather to one of Trivers's daughters. Trivers joined the Black Panther Party in 1979. He and Newton published an analysis of the role of self-deception by the flight crew in the crash of Air Florida Flight 90. Trivers was "ex-communicated" from the Panthers by Newton in 1982 for "his own good".
Trivers died in Mount Vernon, New York, on March 12, 2026, at the age of 83.
Career
Trivers studied evolutionary theory with Ernst Mayr and William Drury at Harvard from 1968 to 1972, when he earned his PhD in biology. At Harvard, he published a series of some of the most influential and highly cited papers in evolutionary biology. His first major paper as a graduate student was "The evolution of reciprocal altruism", published in 1971. The primary insight of Trivers was that the key variable underlying the evolution of sex differences across species was relative parental investment in offspring.
He was on the faculty at Harvard University from 1973 to 1978, where he continued his work, publishing an influential paper on facultative sex ratio determination (1973), and parent–offspring conflict (1974). He has also contributed by explaining self-deception as an adaptive evolutionary strategy (first described in 1976) and discussing intragenomic conflict.
Trivers was awarded the 2007 Crafoord Prize in Biosciences for "his fundamental analysis of social evolution, conflict and cooperation". In 2015, years after Epstein's conviction, Trivers defended Epstein's reputation by minimising his crimes and saying that he already served his prison sentence and settled lawsuits against him. Of Epstein's assaults on underage girls, Trivers told a reporter, "By the time they're 14 or 15 they're like grown women were 60 years ago, so I don't see the acts as so heinous." In 2017, Trivers described his relationship with Epstein as "valuable mostly because he is extremely bright, open-minded and widely travelled... he gives me consistent, warm support without me having to write endless applications for grants, and trusts me to put it to good use".
Rutgers teaching controversy
In 2015, Rutgers University suspended Trivers with pay for refusing to teach a class on "Human Aggression" that had been assigned to him. Trivers told the class that he knew nothing about the subject and that he would do his best to learn the subject along with them with the help of a guest lecturer. Rutgers suspended Trivers for refusing to teach and for involving the students in the controversy. In an interview with the student newspaper The Daily Targum, Trivers described himself as "one of the greatest social theorists in evolutionary biology alive, period", and stated that the assigned subject was out of his area of expertise, adding "You would think the university would show a little respect for my teaching abilities on subjects that I know about and not force me to teach a course on a subject that I do not at all master."
Significant publications
Papers
- Trivers, R. L. (1972). Parental investment and sexual selection. In B. Campbell (Ed.) Sexual selection and the descent of man, 1871-1971 (pp 136–179). Chicago, Aldine.
- Trivers, R. L. (1991). Deceit and self-deception: The relationship between communication and consciousness. In: M. Robinson and L. Tiger (eds.) Man and Beast Revisited, Smithsonian, Washington, DC, pp. 175–191.
Books
- Trivers, R. L. (1985) Social Evolution. Benjamin/Cummings, Menlo Park, CA.
- Trivers, R. L. (2002) Natural Selection and Social Theory: Selected Papers of Robert L. Trivers. (Evolution and Cognition Series) Oxford University Press, Oxford.
- Burt, A. & Trivers, R. L. (2006) Genes in Conflict : The Biology of Selfish Genetic Elements. Belknap Press, Harvard.
- Trivers R, Palestis BG, Zaatari D. (2009) The Anatomy of a Fraud: Symmetry and Dance TPZ Publishers
- Trivers R (2011) The Folly of Fools: The Logic of Deceit and Self-Deception in Human Life Basic Books
- Trivers R (2015) Wild Life: Adventures of an Evolutionary Biologist. Plympton.