mike, for interdemic selection (one form of group selecction) there are models where altruists help the group grow but decrease in frequency over time, but then there is a disturbance where the groups reassort. at this point the altruists are at less an advantage and the groups without altruists go extinct, and the process begins anew as altruist frequencies decrease globally. see d.s. wilson’s Unto Others for exposition (or an intro pop genetics book).
mike, for interdemic selection (one form of group selecction) there are models where altruists help the group grow but decrease in frequency over time, but then there is a disturbance where the groups reassort. at this point the altruists are at less an advantage and the groups without altruists go extinct, and the process begins anew as altruist frequencies decrease globally. see d.s. wilson’s Unto Others for exposition (or an intro pop genetics book).