It's difficult to make any sweeping statements as to the motivations present in power dynamics across cultures and throughout history. Many books can and have been written on the subject. One can speak in generalities, and I tend to agree with Machiavelli that it is in our nature to amass power for ourselves and our tribe, an impulse that is not monopolized by one gender.

Certainly biology can to some degree explain why men outnumber women in positions of power. I don't know if it's fair to say that men are naturally more aggressive (although the evidence points in that direction), but in small-group tribal settings, certainly those members who possess superior physical strength will be at a great advantage when exerting their will. This initial leg-up will multiply across generations as power is cemented and patrilineal inheritance entrenched as a cultural norm.