John Maynard Smith was one of the most important figures in modern biology, his main contribution being to use game theory to show how unexpected or counterintuitive results could arise and remain stable. He also worked out how sex could lead to more viable and better protected creatures despite the loss of half the genome in every sexual exchange.

The ESS or evolutionarily stable strategy is the biological equivalent of the economist's Nash equilibrium. Evolution stabilises onto a mixed strategy or a mixture of strategies such that no alternative strategy can be more successful. An animal may have powerful antlers, but seldom uses them in their full offensive capacity. The cost of growing better antlers to win more fights has to be offset against the danger of injury in entering more fights. This explains why competition between males is usually not a fight to the death, but a lot of ritual and posturing.

Maynard Smith was born in London on 6 January 1920, and went to live in the West Country on his father's death eight years later. Here his fascination with nature began. At Eton, the masters' loathing of the great Marxist biologist J.B.S. Haldane impressed itself on the young Maynard Smith's mind as a good reason for learning more about him.

However, he read engineering at Cambridge, not biology; and here he exploited the rules so as to become the first married undergraduate in Trinity by the expedient of installing his new wife Sheila as his landlady, in 1941. He then worked for an aircraft company.

He became a biologist by doing a degree in zoology under Haldane at University College London. He became professor of biology at the University of Sussex in 1965, and remained there emeritus, retiring in 1985, up to his death on 19 April 2004. He was a fellow of the Royal Society from 1977.

His work on ESSes was published in the 1972 essay 'Game Theory and The Evolution of Fighting'. In The Evolution of Sex (1978) he worked out a model for the advantage gained by sexual reproduction, namely faster evolution for resilience to parasites. Other books include The Theory of Evolution (1958), Mathematical Ideas in Biology (1968), Models in Ecology (1974), and Theory of Games (1982).

In 1997 the European Society for Evolutionary Biology established the biennial John Maynard Smith Prize for young researchers in evolutionary biology.

Obituary, The Daily Telegraph, 22 April 2004

Long 1999 interview with him at: