IA... chimpanzee dominant males frequently beat females into submission to show their dominance.
A couple of reasons for that:
1. A new female wants to be a part of the group, the dominant male(s) harrass, scare, and
even will beat her so that she knows her place in the hiarchy of the group.
2. To keep order within the group, preventing further chaos.
3. A female who refuses to submit, or comply with the group culture will also be beaten
by the dominant male(s) as a severe punishment and warning to others.
Yes, these are man's closest living relatives

EDIT:
Also when baboons run into rival groups, they fight, and some of the females
get kidnapped by the other group. SOME of the females CHOOSE to go with
the other group in order to potentially improve her status. The ones that choose
to leave, but wind up back in their own group get severely punished by dominate
males for trying to leave