John Maynard Smith

John Maynard Smith is presented as a central architect of the book’s account of evolutionary strategy: he turns questions about fighting, cooperation, and mating into comparisons among inherited behavioral policies, asking which ones can persist against alternatives. His importance lies not in portraying animals as conscious calculators but in showing how selection can produce behavior that operates as if costs, benefits, and rivals had been assessed. Across these examples, his methods also expose the limits of simple models and attractive explanations.

Strategy and the evolutionarily stable state

In the discussion of aggression, Maynard Smith is credited with expressing forcefully and clearly an idea that ethologists had recognized only vaguely: whether an animal should fight, escalate, or retreat can be understood through a cost-benefit analysis. The costs include time and energy as well as the possibility of injury; the benefits depend on what is at stake. The book illustrates the calculation with an elephant seal weighing whether to challenge a rival who controls a harem. A challenger might eventually gain the resource by waiting, feeding, and growing stronger rather than fighting immediately. The seal’s imagined reasoning is explicitly a device for explaining selection, not a claim that an animal consciously deliberates.

Working with G. R. Price and G. A. Parker, Maynard Smith used game theory to make this strategic approach precise. A strategy is a pre-programmed behavioral policy: an animal behaves as though it follows instructions, without consciously formulating them. An evolutionarily stable strategy is one that, once adopted by most of a population, cannot be bettered by a deviant alternative. The outcome depends on what others do, and selection penalizes departures from a strategy that has become stable. The concept therefore shifts attention from identifying an individually “best” action to asking which policy succeeds in the population it encounters.

The book first makes the framework concrete through the deliberately simple Hawk–Dove model. It then stresses that the model is an aid to thought, not a literal account of animal life. Maynard Smith and Price’s Retaliator strategy adds conditional response: it begins with conventional threatening, responds forcefully if attacked, and behaves less aggressively when facing another Retaliator. Other strategies in the comparison include Bully and Prober-retaliator, which test an opponent’s response in different ways. In a computer simulation of the five strategies, Retaliator emerges as stable; Prober-retaliator comes close, while Hawk, Dove, and Bully each can be invaded under the conditions described. A substantial drift toward Dove could alter the balance, giving more aggressive strategies an advantage and allowing a mixture of strategies, perhaps with gentle oscillations, to predominate.

This result helps explain the book’s image of a “gloved fist”: aggression need not be either unlimited attack or harmless display. Its form depends on the costs and rewards of the contest. An elephant seal’s potential prize—a near-monopoly over a large harem—can make a fight worth substantial risk. For a Great tit feeding nestlings, by contrast, time spent in a contest competes with the need to catch prey at an average rate of one every thirty seconds. The model’s strategic logic remains useful, but its outcomes depend on the actual payoffs of the animals’ circumstances.

Asymmetry and convention

Maynard Smith and Parker extend the analysis beyond contests between equally matched opponents. Contestants can differ in size or fighting equipment, in the amount each stands to gain, or in an apparently arbitrary feature such as who arrived first. The second kind of difference matters, for example, when an older male has less of his reproductive life ahead of him and therefore may have less to lose from injury than a younger rival.

The arrival-order example shows how a convention can become stable even when the distinction itself confers no inherent advantage. A population might settle on the rule that the resident attacks and the intruder retreats; the reverse convention could also become stable. Once either rule is common, deviants are penalized. Under the resident-wins convention, opponents can settle disputes promptly, each winning half the contests without injury or wasted time. A mutant that always attacks risks injury when it meets a resident, while the mutant following the reverse convention loses more often and is also exposed to injury. If chance instead allowed the reverse convention to become the majority, it could set the stable norm. The theory thus accounts for the possibility of occasional flips between alternative stable conventions without treating either as intrinsically correct.

Applications beyond fighting

The same strategic method is applied to sexual behavior, where the book rejects the idea that a coordinated “conspiracy of females” can simply be assumed. Instead, it sets out competing behavioral programs: Coy females require prolonged courtship, while Fast females mate immediately; Faithful males continue courting and help rear young, while Philanderers leave to seek other mates and do not remain as fathers. These are presented as a simplified set of strategies, not as the only possible behaviors. The point of invoking Maynard Smith’s method is to analyze their outcomes through interacting strategies and evolutionary stability rather than assume that one sex can impose a common plan on the population.

Maynard Smith also appears as a critic and mathematical tester of the handicap principle. The proposed explanation is that a costly handicap can advertise a male’s underlying quality: females that prefer handicapped males might thereby choose males whose other genes have enabled them to survive despite the cost. For the account to work as described, the genes producing the handicap must affect sons, while the genes for the preference affect daughters. The book reports that geneticists who tried to formulate the principle mathematically had not succeeded in producing a workable model. Maynard Smith was among them, and the author’s judgment is that the difficulty may indicate a flaw in the principle rather than a lack of ingenuity among its modelers. This episode gives his role a critical edge: an evolutionary story that sounds plausible still has to withstand formal analysis.

Cooperation and scientific exchange

Maynard Smith’s strategic framework also bears on delayed cooperation. In discussing reciprocal altruism, the book notes that W. D. Hamilton’s concept of the evolutionarily stable strategy could have provided a natural way to express R. L. Trivers’s argument. Trivers had already invoked the Prisoner’s Dilemma, suggesting that he was thinking in a related game-theoretic direction. This places Maynard Smith’s work within a wider intellectual development: concepts used to analyze aggression can also clarify the conditions under which favors are returned rather than exploited.

That connection becomes explicit in the account of Robert Axelrod’s second Prisoner’s Dilemma tournament. After Axelrod circulated the first results, Maynard Smith submitted the unusually forgiving Tit for Two Tats. The tournament drew 62 entries, with Random added for 63; unlike the first contest, the number of moves per game was left open. Entrants divided between those who adopted the lesson that nice and forgiving strategies did well and those who expected others to do so and tried to exploit them. Tit for Tat, submitted by Anatol Rapoport, won again, scoring 96 percent of the benchmark. Nearly all of the top fifteen strategies were nice, and nearly all of the bottom fifteen were nasty, but Tit for Two Tats did not win: subtler exploitative strategies could prey on such extreme forgiveness. The changed result also demonstrated that tournament success depends on the strategies included in the field.

The author did not enter the second tournament. Instead, after Axelrod invited submissions and circulated his early results, he urged Axelrod to consult W. D. Hamilton, who was in another department at the University of Michigan. Axelrod contacted Hamilton, and their collaboration produced a 1981 paper in Science, which received the Newcomb Cleveland Prize of the American Association for the Advancement of Science. The author credits that paper with giving due recognition to the evolutionarily stable strategy approach. The contrast is between a round-robin score—performance against an arbitrary set of submitted strategies—and the broader question of whether a strategy resists invasion. Tit for Tat was robust across the tournament’s field, but robustness against that field was not by itself a general answer to what makes a strategy evolutionarily stable.

Theoretical significance and limits

Across the book, Maynard Smith’s contribution is a way of translating apparently purposeful conduct into selection among behavioral alternatives. Animals need not calculate consciously for a strategy to be described as a set of instructions; the language makes the logic tractable while leaving the mechanism non-conscious. The same caution applies to talk of genes behaving as agents: such purpose-language is a metaphor for the differential persistence of variants, not evidence of intention. Maynard Smith’s game-theoretic work is important because it supplies a disciplined structure for that shorthand, making the assumptions, alternatives, and conditions of stability visible.

The account does not present every model as a direct description of nature. Hawk and Dove are explicitly simplified; the results of the contest models depend on payoffs, and actual contexts can differ sharply, from the high prize of an elephant seal’s harem to the time pressure facing a feeding Great tit. Likewise, the handicap principle remains unresolved in the account: its verbal appeal does not settle whether its proposed mechanism can be made coherent mathematically. The recurring value of Maynard Smith’s work is therefore both explanatory and methodological. It shows how competition can generate conditional restraint or cooperation, while insisting that the stability of a strategy depends on its alternatives and on the conditions under which they meet.