Most human females have a relatively wider pelvis than males because the human brain (even in a newborn) is too large to pass through a narrow birth canal. Thus, one of the reasons sexual dimorphism is so much more pronounced in humans than in most other primates is relative brain size. ("Don't trust me," I told her, "check it--the skeletons are there!") Bigger brains require bigger hips.They get the hips so well all can get the brains! Now THAT's science!
It's more than hips. We birth early and the bulk of brain development occurs outside the mother's body. Stimulation by lights, sounds and adults while the brain is growing must have huge implications for intelligence.
The soft skull, cartilaginous fingers, reduced jaw, and underdeveloped lungs indicate the human infants are born "prematurely" compared to the other primates. To reach an equivalent stage, humans would have to have a gestation of about 18-20 months.
Yeah, but my brains disappear when I get near a good set of hips.