The evolutionary game theory of conditional cooperation

In my mathematician’s incarnation, and in my loitering around the Institute Vienna Circle, I came across Austrian Karl Sigmund, the 2003 Gauss Lecturer. Along with John Maynard Smith (the “Etonian communist”) and American George Robert Price, he is at least one parent of evolutionary game theory, a fascinating branch of mathematics that applies game theory to biology or, rather, the evolving populations of life forms. Its tools are valuable to my interest in crowd phenomena. It defines a mathematical framework of contests, strategies and analytics for Darwinian competition. There are indeed mathematical criteria to predict the resulting prevalence of such competing strategies, and evolutionary game theory establishes a rational basis for altruistic behaviors within the Darwinian process. Unlike classical game theory, it centers on the dynamics of strategy change; its determinants that are not just competing strategies but, more importantly, the frequency of occurrence of these strategies within a given population.

Humans have superior adaptive abilities. They are far better than apes at imitation. And they are receptive to praise and reprimand. Man is the perfect pet – domesticated like no other, by ourselves. It is not unusual that a species practices selective breeding on its own kind. Sexual selection is well known since Darwin. An oft-cited example is the peacock’s tail: it does not facilitate survival but only impressing the female of the species – although recent research puts that in question. A male characteristic and the female preference for it spread across the population.

Of course, domestication does not only require selective breeding of just any given characteristic. Said characteristic must also have an economic benefit. What is the economic utility of humans? They don’t contribute commodities such as wool or eggs, but they contribute services. There are other service animals as well: horses serve as means of transportation, dogs as a hunting tool or an alarm device. What purpose do humans serve? They serve as partners of other humans. A partner is someone amenable to assistance, but only on condition of reciprocity.

Indeed, human readiness to cooperate with partners, their “conditional cooperation,” is a salient characteristic. And it is unique. While bees or ants also cooperate on a large scale, they do so only within their beehive or anthill, that is to say, with their own siblings. Humans are rather unique in that they are capable of cooperating also with individuals to whom they are not related.

Such cooperation is grounds for the success of our species. There appear to be no natural limits to the degree of our communal enterprise. That seems odd: should evolution not favor creatures that primarily maximize their own interests?