Robert Trivers, the revolutionary evolutionary biologist whose theories on human cooperation, competition, and self-deception reshaped understanding of social behavior, died on March 12 at age 83. His death, confirmed by family, leaves a void in a field he fundamentally challenged. Trivers, often compared to Charles Darwin for his intellectual audacity, proposed groundbreaking concepts like reciprocal altruism – the idea that helping non-relatives is evolutionarily beneficial through future exchanges – and parent-offspring conflict, arguing familial relationships are a battleground of genetic interests rather than pure harmony.

His 1971 paper on reciprocal altruism, applying game theory to evolution, and his 1974 work on parent-offspring conflict were seminal. Yet, his career was as tumultuous as his theories. He clashed with Harvard colleagues, joined the Black Panthers, and controversially defended convicted sex offender Jeffrey Epstein, whom he acknowledged funded his research.

Mental health struggles, including bipolar disorder, led to hospitalizations and delayed tenure. Despite academic friction, his 1976 foreword to Richard Dawkins' 'The Selfish Gene' on self-deception was profoundly influential, arguing humans evolve to unconsciously lie to avoid detection. He won the Crafoord Prize in 2007, the field's highest honor.

His legacy is complex: a brilliant, disruptive mind whose work forced a re-evaluation of human nature, even as his personal life remained intensely controversial.