Native American women were gatherers and physical healers, while men were hunters and 'mental' healers. The men were protectors, because that is exactly what they had to do, protect the women and children, because they were in fact stronger. Even Animals work this way. Chimpanzee 'men' must protect the female chimpanzees, because they are often caring for their young. Merecats live in a comunity, and it is often the eldest, alpha female merecat that 'babysits' the young while others go out, because she knows how to care for them, and is often the weakest because of old age.
Lions also have gender boundaries.
Besides the difference in hair, the men are again there to protect the female lion while she is pregnant and nursing her young. When the young are old enough, or there are no young, it is the female Lion who does all the hunting, often teaching the young lions how to kill antelopes. Bulls have horns to protect the cows, oxen, sheep, water buffallo, and many other hoofed animals are the same way. The male animals protect the female animals, because they often have children and are nursing. These are just my beleifs.