I have just realized that I keep mentioning David Sloan Wilson a lot (see the list of links below), always in a positive light as I think he is one of the pioneers of modern evolutionary theory (as soon as those drunk on Williams 1966 and Dawkins’ opus retire or die) but have never really written a good post on group selection. I’ll have to do this one day soon – that may be my contribution to the Basic Concepts collection.
Anyway, Wlison just gave a talk in which he presented my favourite example of the test of group selection – in chickens:
Two experiments using chickens show another aspect of evolution regarding selection. In the first experiment, groups of chickens in cages were evaluated for egg-laying. The best egg-layer within each cage was chosen and put together with the other prolific egg-layers. The second experiment took the best caged groups of egg-layers. The result of the second experiment after a few generations was healthy, sociable, egg-laying chickens. The result of the first experiment after a few generations was fighting and anti-social chickens that maimed and killed each other.
“You pick the best,” Wilson joked, “and in six generations you get sociopaths.”
Those two papers actually came out in Poultry Science, not Evolution, thus they are not as well known by the evolutionary community as they should be. What Wilson did not mention in his talk is that the group-selection experiments resulted, over just a few generations, in a greater egg-production than ever achived in a couple of thousand years of selective breeding of chicken. It also resulted in a complete loss of need for de-beaking of chickens, which is a nasty procedure in poultry industry.
Perhaps these chicken don’t peck each other to death because they all adopted the identical religious beliefs LOL!
Update: Mike has more.