I think it suffices to show that selection can operate at the level of the group. Even if all of the traits involved provide some advantage to individuals, if they also provide an advantage to the group, then group-level selection needs to be considered.
It is more interesting if you can show that a trait that does not confer an advantage to an individual, has an effect on group selection. But it is an unreasonable bias to demand that group selection requires traits that do not provide any advantage to an individual, and yet at the same time not insist that the theory of individual selection requires traits that do not provide any advantage to the group.
I should clarify—“group selection” connotes what Tim is describing: Selection for altruistic traits in individuals, by selection at the group level. That’s because, historically, group selection has been invoked only to explain things that individual selection can’t.
However, this has led to people excluding selection at the group level from models and simulations, because “group selection bad”.
I think it suffices to show that selection can operate at the level of the group. Even if all of the traits involved provide some advantage to individuals, if they also provide an advantage to the group, then group-level selection needs to be considered.
It is more interesting if you can show that a trait that does not confer an advantage to an individual, has an effect on group selection. But it is an unreasonable bias to demand that group selection requires traits that do not provide any advantage to an individual, and yet at the same time not insist that the theory of individual selection requires traits that do not provide any advantage to the group.
I should clarify—“group selection” connotes what Tim is describing: Selection for altruistic traits in individuals, by selection at the group level. That’s because, historically, group selection has been invoked only to explain things that individual selection can’t.
However, this has led to people excluding selection at the group level from models and simulations, because “group selection bad”.