Men and Women are very different. They have both different mating startegy. Women are selected on their fertility wich can be expressed as youthness and beauty. Men are selected on their providing ability and protect ability. Women have very limited eggs and thus they need to be more selective of who they mate with. The goal of the female is to select the male with the most strong genes so that she can give birth to a strong child. The goal of men is to spread their genes. Its important that they have many copies of their genes. So the important thing for women is quality and for men its quantity. This leds women to seek partners higher than themselfs. In order to choose a geneticaly strong men she will monkey branch. This means that she will go from a regular male to a stronger male. This hypergamous nature of females has no limits! They will keep monkey branch until their value drops heavily in their 30s. The Hypergamy of women leds to cheating and bastard children. She will often choose men way above her level. This will cause high quality men to pump and dump hypergamous women. The males goal is to spread their genes so that means that the male has a pump and dump strategy. The females goal is to select high quality genes so that means that she will be dumped by a high quality men. This is why monogamy has been implented in the past. Monogamy prevented the defective hypergamous instinct of women and it prevented high quality men of their pump and dump strategy.