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John Maynard Smith (1920–2004)

Maynard Smith was a theoretical evolutionary biologist who brought mathematical rigour to questions about animal behaviour, sexual reproduction, and the structure of evolutionary history. He trained first as an aeronautical engineer, then retrained as a geneticist under J. B. S. Haldane. Two of his most influential contributions — evolutionary game theory and the concept of the evolutionarily stable strategy (ESS), and the framework of major evolutionary transitions developed with Eörs Szathmáry — each opened a field that continues after him.

Life

Born 6 January 1920 in London. His father, Sidney Maynard Smith, a surgeon, died in 1928 when John was eight; the family moved to Exmoor, where he developed an early interest in natural history. Educated at Eton College — unhappy with the lack of formal science education, but inspired by reading the work of old Etonian J. B. S. Haldane.

First degree in engineering at Trinity College, Cambridge. He worked on military aircraft design during the Second World War. After the war he took a second degree in genetics under Haldane at University College London, working on fruit fly (Drosophila) genetics. He joined the Communist Party as a young man and left after Hungary in 1956. He underwent a life shift from pacifism and from Christianity to atheism.

In the early 1960s he was a founding member of the University of Sussex and founding dean of the School of Biological Sciences — a post he held while the school was built from scratch. He remained at Sussex for the rest of his career. Elected FRS in 1977. Awarded the Darwin Medal (1986), the Balzan Prize for Genetics and Evolution (1991), the Crafoord Prize (1999, jointly with Ernst Mayr and George C. Williams), and the Kyoto Prize (2001). He died at home on 19 April 2004, aged eighty-four.

Evolutionary game theory and the ESS

The idea of applying game theory to evolutionary biology had been suggested by Richard Lewontin in a 1961 paper. Maynard Smith developed it into a sustained programme around the concept of the evolutionarily stable strategy. The collaboration began when he encountered George R. Price’s work while peer-reviewing one of Price’s papers; together they mathematically formalised the concept.

The ESS was first presented as a verbal argument in the 1972 essay collection On Evolution, then published with Price in the 1973 Nature paper “The Logic of Animal Conflict,” with a full treatment in Evolution and the Theory of Games (1982):

“An ESS or evolutionarily stable strategy is a strategy such that, if all the members of a population adopt it, no mutant strategy can invade.”

The Hawk–Dove game — two strategies competing over a resource, one escalating, one retreating — became the paradigmatic example. The framework has had broad uptake across biology and beyond: behavioural ecology in its native domain; economics, anthropology, evolutionary psychology, and political science outside it.

The evolution of sex

The Evolution of Sex (1978) drew attention to a paradox: an asexually reproducing mutant in a sexual population doubles in frequency each generation, since it does not pay the cost of producing males. The “two-fold cost of sex” had been suggested by earlier workers, but Maynard Smith was the first to articulate it as a central explanatory problem — why does sexual reproduction persist despite its apparent disadvantage? The question generated a large research programme. He had anticipated elements of “good genes” theory — the idea that female mate choice evolves because choosy females obtain heritable fitness benefits for their offspring — in a 1958 article for the Darwin centennial.

The major transitions in evolution

Developed with Eörs Szathmáry; published as The Major Transitions in Evolution (Oxford, 1995) with a popular companion, The Origins of Life (1999). The framework identifies a series of events in which entities capable of independent replication came to replicate only as part of a larger whole, with associated changes in how information is stored and transmitted:

“Entities that were capable of independent replication before the transition can replicate only as part of a larger whole after it.”

The 1995 list of transitions: replicating molecules to populations in compartments; independent replicators to chromosomes; RNA as gene and enzyme to DNA and protein; prokaryotes to eukaryotes; asexual clones to sexual populations; protists to multicellular organisms; solitary individuals to colonies with non-reproductive castes; primate societies to human societies with language.

The list is not a settled inventory. Szathmáry himself updated it in 2015, removing sex as a transition and adding endosymbiotic events. Other workers — Richard Michod, David Queller, Matthew Herron — have proposed alternative versions. The 1995 framework remains the canonical reference point, but it has itself evolved.

Signalling and animal communication

Later work, including with David Harper, applied ESS reasoning to the evolution of honest signals. Animal Signals (2003) developed the theory of when signals can be trusted — under what conditions natural selection maintains honest communication between organisms with conflicting interests.

Drosophila and the biology of ageing

Maynard Smith’s early experimental work pioneered the use of Drosophila as a model organism for the study of ageing. In the late 1950s and early 1960s he produced one of the earliest demonstrations of the survival cost of reproduction and evidence against the somatic mutation theory of ageing.

Exposition

He was an unusually clear writer. The Theory of Evolution (1958, with later editions) and Evolutionary Genetics (1989) were widely used textbooks. His expository gift — the use of simple models to illuminate complex problems — is itself part of the contribution; several generations of evolutionary biologists learned the field through his prose.

Where Maynard Smith stops

The ESS framework models evolution as a game between strategies — powerful for analysing conflict and cooperation, but operating within the assumption that the relevant strategies and payoffs are given. How new strategies arise, how the game itself changes, how the space of possible strategies expands over evolutionary time — these are not questions the ESS framework addresses. The major transitions framework describes what happened — entities that could replicate independently coming to replicate only as part of a larger whole — but the mechanisms driving each transition are specific to each case; the framework identifies the pattern without providing a single causal theory that unifies them. Whether the transitions share a common mechanism or are united only by the pattern of individuality-recomposition is a question the framework leaves open.

Key works

See also: Mutualism · Maturana · Solé