Ass men unite! (Not like that!)
Apparently we are genetically wired to like rear ends. Early in mans history, we "did the deed" from behind, and firm buttocks also indicated a good runner, thus better equipped to deal with running away from predators. That's also why we like cleavage, it reminds us of rear ends. More usless info from the brain of Zebrazuk.
Speaking of rear ends, is it Zafira?