Pinker takes on group selection

I was surprised at the easy run that group selection has recently had in social science circles, so I am pleased to see that Steven Pinker has waded into the fray with an essay in Edge. Pinker’s whole essay is worth a read, but there were a couple of parts of it that I particularly liked.

The first was Pinker’s highlighting that when many social scientists talk of group selection, they are talking of cultural group selection. Pinker writes:

[M]ost of the groupwide traits that group selectionists try to explain are cultural rather than genetic. The trait does not arise from some gene whose effects propagate upward to affect the group as a whole, such as a genetic tendency of individuals to disperse which leads the group to have a widespread geographic distribution, or an ability of individuals to withstand stressful environments which leads the species to survive mass extinction events. Instead, they are traits that are propagated culturally, such as religious beliefs, social norms, and forms of political organization. Modern group selectionists are often explicit that it is cultural traits they are talking about, or even that they are agnostic about whether the traits they are referring to are genetic or cultural.

What all this means is that so-called group selection, as it is invoked by many of its advocates, is not a precise implementation of the theory of natural selection, as it is, say, in genetic algorithms or artificial life simulations.

Cultural group selection is less prone than “biological group selection” to the criticism that migration and gene transfer between groups prevents genetic differentiation from emerging. It may be possible to argue that when someone joins the group, they absorb the culture or that it is the culture of the whole population that matters. However, you then run into Pinker’s broader question of whether the concept of cultural group selection adds anything to “history”.

Another interesting point Pinker makes is that apparently altruistic behaviour may be more a case of manipulation than evidence of a generally selfless inclinations.

What we don’t expect to see is the evolution of an innate tendency among individuals to predictably sacrifice their expected interests for the interests of the group—to cheerfully volunteer to serve as a galley slave, a human shield, or cannon fodder. … What could evolve, instead, is a tendency to manipulate others to become suicide attackers, and more generally, to promulgate norms of morality and self-sacrifice that one intends to apply in full force to everyone in the group but oneself. If one is the unlucky victim of such manipulation or coercion by others, there’s no need to call it altruism and search for an evolutionary explanation, any more than we need to explain the “altruism” of a prey animal who benefits a predator by blundering into its sights.

This manipulation extends into the manner in which we treat non-kin as kin.

The cognitive twist is that the recognition of kin among humans depends on environmental cues that other humans can manipulate. Thus people are also altruistic toward their adoptive relatives, and toward a variety of fictive kin such as brothers in arms, fraternities and sororities, occupational and religious brotherhoods, crime families, fatherlands, and mother countries. These faux-families may be created by metaphors, simulacra of family experiences, myths of common descent or common flesh, and other illusions of kinship.

Pinker makes some other good points, but one element I alluded to above is missing from Pinker’s argument - the critique of group selection on the basis of migration and gene flow between groups. While advocates of group selection in humans often spend much effort on showing how human groups experienced regular conflicts and wars, little is focused on the likely transfer of people between groups through capturing women from the losers in war or through exogamy. It takes little inter-group migration to prevent genetic differentiation between groups. If you were to ask what it would take for me to believe that group selection was a significant force in shaping human traits, it is on this point that you would need to change my mind.

*I make some comments on the responses to Pinker in this later post.