Banning women from combat is essential to survival. Keeping one's fertile females safe from harm has been with us since the first humans banded together into tribes for mutual defense. If your fertile females are all killed or captured, your tribe dies out. Protecting females from harm is still with us today. Don't believe me? Try slapping your wife/girlfriend in a public place with other men around sometime and see how quickly the rest of the males descend on you and proceed to kick your butt. What is there justification for attacking you? "You never hit a girl" will be their response every time. Even if the "girl" is more than capable of killing you, you will be expected to die rather than be allowed to lift a hand to defend yourself.