Robert L. Trivers is an American evolutionary biologist and sociobiologist, most noted for proposing the theories of reciprocal altruism (1971), parental investment (1972), and parent-offspring conflict (1974). Other areas in which he has made influential contributions include an adaptive view of self-deception (first described in 1976) and intragenomic conflict. Along with George C. Williams, Trivers is arguably one of the two most influential evolutionary theorists alive today.

Trivers originally went to Harvard to study Math, but wound up studying U.S. history in preparation to become a lawyer. He took a psychology class after suffering a breakdown, and was very unimpressed with the state of psychology. He was prevented from getting into Yale law school by his breakdown, and wound up with a job writing social science textbooks for children (never published, due in part to presenting evolution by natural selection as fact).

This exposure to evolutionary theory led him to graduate work with Ernst Mayr at Harvard 1968-1972 (he never got a bachelor's degree anywhere). He was on faculty at Harvard 1973-1978, then moved to UC Santa Cruz.

He met Huey P. Newton, Chairman of the Black Panther Party, in 1978 when Newton applied (while in prison) to do a reading course with him as part of a graduate degree in History of Consciousness at UC Santa Cruz. Trivers and Newton became close friends, Newton was godfather to one of Trivers' daughters.

Trivers joined the Black Panther Party in 1979. Trivers and Newton published an analysis of the role of self-deception by the flight crew in the crash of Air Florida Flight 90 (Trivers, R.L. & Newton, H.P. Science Digest 'The crash of flight 90: doomed by self-deception?' November 1982, pp 66,67,111).

Trivers was a faculty member at UC Santa Cruz 1978-1994. He is currently a Rutgers University notable faculty member. He was named one of the 100 greatest thinkers and scientists of the 20th Century by 'Time' magazine.