Robert Trivers, an American evolutionary biologist and sociobiologist, died on March 12, 2026, at age 83.
He was known for proposing the theories of reciprocal altruism, parental investment, facultative sex ratio determination, and parent–offspring conflict. Trivers also contributed to evolutionary explanations of self-deception as an adaptive strategy and wrote on intragenomic conflict.
Born in Washington, D.C., on February 19, 1943, he profoundly influenced evolutionary biology, animal behavior, and sociobiology.
Robert Ludlow Trivers (/ˈtrɪvərz/; 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.