David Sloan Wilson reports:

The newest issue of Science Magazine includes a lovely demonstration of multilevel selection by Omar Tonsi Eldakar, my former graduate student, who is currently at the University of Arizona’s Center for Insect Science.

Readers who have been following my “Truth and Reconciliation for Group Selection” series will be well prepared to appreciate the import of the Science article. Group selection requires variation among groups. Variation among groups is eroded by dispersal. Therefore, group selection can only take place in groups that are highly isolated from each other. That is part of the reasoning the led to the conclusion that group selection can only take place under highly restrictive conditions.

But wait. This argument assumes that dispersal is random. What if dispersal is conditional? What if individuals stay in groups when they are sufficiently cooperative but leave when they become overrun by selfish individuals? In this case, dispersal might increase variation among groups, improving the conditions for group selection. John Pepper and Athena Aktipis (featured in T&R XII) are two theorists who have studied this “walk away” process in agent-based simulation models.’