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George C. Williams (1926–2010)

Williams was an evolutionary biologist whose Adaptation and Natural Selection (1966) provided the rigorous conceptual argument that Dawkins’ Selfish Gene later popularised. The book’s central move: treat adaptation as a special and onerous concept, not to be invoked without evidence of selection at the appropriate level. Most apparent cases of group-level adaptation — traits that seem designed to benefit the species — can be explained more parsimoniously as consequences of individual- or gene-level selection. The argument did not prove that group selection never occurs; it demonstrated that the explanatory bar for invoking it is far higher than mid-century biology had assumed. The effect was to displace group-selectionist reasoning for two decades and to establish the gene-centric perspective as the default framework in evolutionary biology.

Life

Born 12 May 1926 in Charlotte, North Carolina. Grew up in a working-class family. Drafted into the US Army during the Second World War; served in Italy. After the war, BA in zoology from the University of California, Berkeley (1949). PhD from the University of California, Los Angeles (1955), working on fish biology.

Joined the faculty at what was then the State University of New York at Stony Brook in 1960, remaining for his entire career. Professor of ecology and evolution; retired in 1990 but continued to publish. Awarded the Crafoord Prize in Biosciences (1999, jointly with Ernst Mayr and John Maynard Smith) — the Royal Swedish Academy’s equivalent of the Nobel in fields the Nobel does not cover.

Suffered from progressive dementia in his final years. Died 8 September 2010 in Stony Brook, New York, aged eighty-four.

Adaptation and Natural Selection

Adaptation and Natural Selection: A Critique of Some Current Evolutionary Thought (1966). The book that reshaped how evolutionary biologists think about the units of selection.

The target was the loose group-selectionist reasoning that had become common in post-Synthesis biology — the habit of explaining traits by appeal to species benefit. V. C. Wynne-Edwards’ Animal Dispersion in Relation to Social Behaviour (1962) was the most systematic expression of this tendency, arguing that animals regulate their populations for the good of the species. Williams argued that this reasoning was both unnecessary and methodologically careless. If a trait can be explained by selection on individuals or genes, there is no warrant for invoking group-level selection. Group selection requires that groups behave like individuals in a population of groups, with differential group fitness and group-level heritability — conditions that are restrictive and rarely demonstrated.

The parsimony argument was not Williams’ invention — Fisher had been sceptical of group selection, and Haldane had noted the implausibility of altruism evolving without kinship mechanisms. Williams gave the argument its most sustained and rigorous expression, and he did so at a moment when biology was ready to hear it. Hamilton’s inclusive fitness theory (1964) had just provided a gene-level mechanism for the evolution of apparent altruism; Williams’ critique provided the conceptual framework that made the gene-level perspective a programme rather than a collection of results.

The book also introduced a distinction between adaptation and fortuitous benefit. A trait is an adaptation only if it was shaped by selection for its current function. Many useful features of organisms are by-products of other adaptations or consequences of physical and developmental constraints — useful, but not designed. The distinction anticipated debates that Gould and Lewontin later sharpened in the Spandrels critique (1979), though Williams remained more firmly adaptationist than either.

The evolution of senescence

Williams’ 1957 paper “Pleiotropy, natural selection, and the evolution of senescence” (Evolution 11) proposed the antagonistic pleiotropy hypothesis: genes that confer benefits early in life but exact costs late in life will be favoured by natural selection, because selection pressure declines with age. Organisms that have already reproduced contribute less to future gene frequencies; genes that boost early survival and reproduction at the expense of later health face weaker opposing selection than they enjoy supporting selection.

The hypothesis, alongside Peter Medawar’s mutation accumulation theory (1952), became one of the two main evolutionary accounts of ageing. Both invoke the declining force of selection with age; they differ on mechanism. Medawar proposed that deleterious mutations with late-acting effects accumulate because selection cannot efficiently remove them. Williams proposed that selection actively favours genes with early benefits and late costs. The two mechanisms are not mutually exclusive and both are now considered to contribute.

The evolution of sex

Sex and Evolution (1975). The problem: sexual reproduction is enormously costly. An asexual female passes all her genes to her offspring; a sexual female passes only half — the “twofold cost of sex.” Why, then, is sex so nearly universal among complex organisms?

Williams approached the question from a gene-level perspective. If sex exists, it must provide a gene-level advantage sufficient to overcome the twofold cost. He explored several candidate mechanisms — the lottery model (sex produces varied offspring better suited to unpredictable environments), the tangled-bank model (varied offspring reduce competition among siblings) — without arriving at a single definitive answer. The book opened the problem as a major research programme in evolutionary biology. Hamilton and colleagues later developed the parasite hypothesis — the Red Queen — as a leading explanation: sex generates the genetic variation needed to stay ahead of coevolving parasites. The question remains an active field.

Darwinian medicine

With Randolph Nesse, Williams co-founded the field of evolutionary medicine. Their 1991 paper “The Dawn of Darwinian Medicine” (Quarterly Review of Biology 66) argued that many features of disease and vulnerability — fever, pain, nausea, anxiety — are not malfunctions but evolved defences whose logic becomes visible only when understood in evolutionary terms. Why We Get Sick: The New Science of Darwinian Medicine (1994, with Nesse) brought the argument to a general audience.

The programme does not claim that all disease has an adaptive explanation. It claims that evolutionary thinking — why has selection left this vulnerability in place? — is a necessary complement to the proximate, mechanistic explanations that dominate clinical medicine.

Where Williams stops

Williams’ framework is gene-centric and methodologically adaptationist: it demands that every claim of adaptation meet a gene-level selectionist standard. The parsimony principle — do not invoke group selection when individual selection suffices — is a rule of argument. It tells you how to evaluate claims, not what processes exist. The revival of multilevel selection theory (Sober and D. S. Wilson 1998, and later including E. O. Wilson’s own late-career turn to group selection) reopened the question Williams had largely closed, arguing that the issue is not which level is real but how selection at multiple levels interacts in particular cases. Williams’ programme provides the critical standard but not the multi-level framework that subsequent work has built around it.

Key works

See also: Darwinism · Dawkins · Hamilton · Maynard Smith · Fisher