ELI5: Explain Like I'm 5

Group selection

Group selection is when animals in a group help other animals in the same group survive, even if it means that the animal might not be able to survive as well on their own. For example, if one monkey in the group was about to be attacked by a predator, other monkeys in the group might help him fight it off, even if it puts them in danger. This is group selection because the group of monkeys are working together to make sure that the group survives, even if it means that some individuals might not survive.