visiting the theoretical biology department at the University of Chicago, he studied game theory and began to explore the ways in which evolution is like a game.5

Eventually, Maynard Smith showed that game theory could illuminate how organisms adopt different strategies to survive the slings and arrows of ecological fortune and produce offspring to carry the battle on to future generations. Evolution is a game that all life plays. All animals participate; so do plants, so do bacteria. You don’t need to attribute any rationality or reasoning power to the organisms—their strategy is simply the sum of their properties and propensities. Is it a better strategy to be a short tree or a tall tree? To be a super speedy quadruped or a slower but smarter biped? Animals don’t choose their strategies so much as they are their strategies.

This is a curious observation, I think. If every animal (plant, bug) is a different strategy, then why are there so many different forms of life out there, why so many different strategies for surviving? Why isn’t there one best strategy? Why doesn’t one outperform all the others, making it the sole survivor, the winner of the ultimate fitness sweepstakes? Darwin, of course, had dealt with that issue, explaining how different kinds of survival advantages could be exploited by natural selection to diversify life into a smorgasbord of species (like the specialization of workers in Adam Smith’s pin factory). Maynard Smith, though, took the Darwinian explanation to greater depths, using game theory to demonstrate with mathematical rigor why evolution is not a winner-takes-all game.

In doing so, Maynard Smith perceived the need to modify classical game theory in two ways: substituting the evolutionary ideas of “fitness” for utility and “natural selection” for rationality. In economic game theory, he noted, “utility” is somewhat artificial; it’s a notion that attempts “to place on a single linear scale a set of qualitatively distinct outcomes” such as a thousand dollars, “losing one’s girl friend, losing one’s life.” In biology, though, “fitness, or expected number of offspring, may be difficult to measure, but it is unambiguous. There is only one correct way of combining dif-



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