Why do boys look at girls hips?

There's a scientific study that states that women with a narrower waist than hips are the most desirable to men. It also indicates that a female with wider hips, will have enough energy required to obtain offspring. Studies have also shown that to a male, larger hips promotes good health and it is indeed true. Those with an ideal waist to hip ration, are less likely to have health problems in the future and if a guy doesn't know this intuitively, then chances are he is looking at a girl's hips because its a personal quality he admires about them.