New Scientist is carrying this summary of one scientist's hypothesis that at least some changes toward "handsomeness" in hominids were driven by females choosing better-looking mates over time.

While this may well be true, the evidence she seems to rely on, the size of canines and width of facial features, are heavily influenced by dietary factors as well as any purported sexual competition. It's equally possible that females chose mates who would help them raise increasingly more dependant children instead of fighting with other males for reproductive rights. There is such a strong correlation between sexual dimorphism (the size difference between the sexes of any primate) and male competition that it's one of the few anatomical indicators of behavior. The more males fight over females, the larger they become, and visa-versa.