Robert Trivers

Robert Trivers (Washington, 1943 – 2026) was an American evolutionary biologist and sociobiologist whose ideas reshaped how scientists study cooperation, sex differences and deception in animals, including humans. Trained at Harvard, he is one of the central figures of sociobiology, the school that applies natural selection theory to social behaviour.

Trivers earned his doctorate in biology at Harvard in 1972, after studying evolutionary theory with Ernst Mayr and William Drury. His early papers, published between 1971 and 1974, remain classics. In "The Evolution of Reciprocal Altruism" (1971) he explained how cooperation between unrelated individuals can arise, suggesting that natural selection would favour ways of detecting cheaters. The following year, in "Parental Investment and Sexual Selection", he argued that the key variable behind differences between the sexes is how much each parent invests in the offspring. He then worked on facultative sex ratio adjustment and on parent-offspring conflict. Later he extended his research to self-deception as an adaptive strategy, a theme he developed in "Social Evolution" (1985) and in his book on the logic of human deceit.

His academic career took him through Harvard, the University of California at Santa Cruz and Rutgers University, where he taught until 2015. That year he was suspended for refusing to teach a course on human aggression. Trivers was also linked to Jeffrey Epstein, whose funding he accepted, and his remarks defending Epstein drew sharp criticism, for which he later apologised.

His influence is considerable: concepts such as reciprocal altruism, parental investment and parent-offspring conflict are part of the foundations of contemporary evolutionary biology and evolutionary psychology.