The animal kingdom has it's own way of dealing with life. An animal needs food and shelter. It needs to reproduce. Humans are in there ground essence an animal. Just like any other animal, with a view differences such as standing upstraight and less hairy than most land animals. The order in an herd of humans knows to basic rules. 

Old over young.

Male over female. 

If a female is the oldest in the herd she can be the alpha, the leader. But she has to claim it. She claims it by being the first of the females to step up to a male in order to mate. Since clothes didn't exist it all happened butt naked. The female would step up to a male, turn around, bend over and showed him her backside. That's why men are still fascinated by a womans butt, because at one time it meant sex was on the menu. However, in most cases a man was the leader of a herd. 

Males provided food such as meat and fruit. Males who stayed with the herd protected the females, the children and the retired elderly. Females between age twenty and thirty were almost all year round pregnant. Starting early april with mating and ending late january of the next year with the birth of a new born. To do it all over again with the start of mating season, early april. 

Every day when the males got back with food, the females, the children and the retired elderly were provided. They got their fair share of food without a hassle. Between the remaining males it was all for one. Not standing in line waiting for your share, but get out there and grab whatever you could grab. All to show and find out who is the strongest, the alpha, the leader. Yess, that could change on a daily basis. There was no election and no one was appointed. You only needed to be intimidating, being big, strong and blessed with a big and loud mouth. 

It became the ground reason for greed. Particurliarly amongst males, since they had to put up a fight to get some food. It was a real battle, because you only stayed healthy, fit and strong if you got enough food every day. For males food was what money is today.