There's an anthropologist out there who's got a theory that the Neanderthal people went extinct because they lacked gender roles. They've found evidence that all adult Neanderthals participated in big-game hunting. Females would have been hurt and killed doing this just as often as males. For the population, this is much worse than losing males, since a bunch of females sharing one male could have just as many babies as if each female had a male, but a bunch of males sharing one female will produce just the same number of babies as one male and one female.
Homo sapiens living in stone-age societies and upward invariably have a division of labour based on gender which assigns somewhat less dangerous tasks to females. Probably it's written in our genetic code to tend to do this.
But, y'know. Every group has a few raging egos. Those people are always keen to say that they are better than others because of one thing or another. So a tendancy that was of evolutionary advantage to early humans has become lame cultural ideals about men (or in rarer cases, women) being 'better'.
