FearGod
Freedom Of Mind
It's not needed. It's just wanted.
Ducks don't pick pretty ducks to mate with because they need to. They do it because they want to. They live in rich and easy environments, so finding food and avoiding predators is not a big concern for them.
Chimps live in a tough environment. The beauty of their mate is not the first thing on their mind. Being strong, tough, and resourceful is.
Do you mean the ugly ones can't rape the beautiful ones because food is easy to find?
or maybe rape isn't allowed in their environment.