We previously linked to Steven Pinker's excellent essay on John Brockman's EDGE site, about The False Allure of Group Selection. It elicited about 20 replies from those invited to do so by John Brockman, including one from me and an especially good one from John Tooby.

Now, after all the replies have been gathered in, Steven Pinker himself has written a masterly reply, not back-tracking at all in his criticism of the deeply unhelpful idea of group selection.

Richard

Steven Pinker Replies

According to the defenders of the theory of group selection among the commentators, group-against-group competition is the only way to explain why humans have morality, empathy, culture, language, social norms, and locally useful adaptations such as digesting milk and breathing thin air. At the same time, the theory is mathematically equivalent to standard evolutionary theories based on gene selection or inclusive fitness, so the two theories make identical predictions and can never be empirically distinguished.

This muddle confirms the point of my essay: that the concept of group selection is making a shambles of the application of evolutionary biology to human psychology. It has led commentators to equate human goodness with prowess in tribal competition—as if the only reason we feel compassion for a lame puppy is that it helped our ancestors massacre the villagers across the river. It has prevented them from asking elementary questions, such as whether digesting milk or breathing efficiently could conceivably provide any benefit to the digester or breather as opposed to the group. It has led them to maintain both that group selection is empirically indistinguishable from gene selection and that it is the only theory that can explain of a raft of empirical phenomena, from punishing free riders in experimental games to obeying the categorical imperative when deciding whether to vote.

Group selection has become a scientific dust bunny, a hairy blob in which anything having to do with "groups" clings to anything having to do with "selection." The problem with scientific dust bunnies is not just that they sow confusion; as Tooby notes, the apparent plausibility of one restricted version of "group selection" often bleeds outwards to a motley collection of other, long-discredited versions. The problem is that it also obfuscates evolutionary theory by blurring genes, individuals, and groups as equivalent levels in a hierarchy of selectional units; Tooby and Dawkins remind us that this is not how natural selection, analyzed as a mechanistic process, really works. Most importantly, it has placed blinkers on psychological understanding by seducing many people into simply equating morality and culture with group selection, oblivious to alternatives that are theoretically deeper and empirically more realistic.