TGGP, your description of what group selection is is not in contradiction with mine. I merely described one isolated group, but the concept can apply to more than one of course. Imagine two groups of foxes and rabbits, one in which restraint is developed and selected for because of the greater health of their youth in times of famine, and one in which restraint is not in any gene, in which case the health of that population is generally lower than the restrained group, but still alive because it is not competing with any internal restrained-breeding individuals. This concept even works when the fox groups are isolated and the rabbit population is shared (however unlikely, that is possible.)
As for your last comment,
“However, all those populations would be vulnerable to the overbreeding mutation suddenly appearing, so it would not be a good explanation.”
...I addressed the mechanics of why this wouldn’t be a problem to group selection in my first post.
TGGP, your description of what group selection is is not in contradiction with mine. I merely described one isolated group, but the concept can apply to more than one of course. Imagine two groups of foxes and rabbits, one in which restraint is developed and selected for because of the greater health of their youth in times of famine, and one in which restraint is not in any gene, in which case the health of that population is generally lower than the restrained group, but still alive because it is not competing with any internal restrained-breeding individuals. This concept even works when the fox groups are isolated and the rabbit population is shared (however unlikely, that is possible.)
As for your last comment,
“However, all those populations would be vulnerable to the overbreeding mutation suddenly appearing, so it would not be a good explanation.”
...I addressed the mechanics of why this wouldn’t be a problem to group selection in my first post.