Women need two things.
They need great genes, and they need a mate who will stick around to help
raise the child. As we now know, these two goals aren‘t always achieved by
the same man.
But keep these two drives in mind as we move forward.
The ̳Keep-Him‘ Strategy
To encourage a man to commit, women have developed an unusual
strategy...
Humans are unique in the animal kingdom for having ―lost estrus‖ and
―hidden ovulation‖. While most animals outwardly signal they are sexually
receptive, such as a chimpanzee‘s red and inflated butt, human females do not
reveal (or even know themselves) when they are fertile.
How did this unusual state of affairs come about? Women who were able to
keep a man around for the duration—rather than just during a brief fertile
period—had more support raising their weak and burdensome human child and
thus were more likely to successfully pass on their genes.
Since a man has no signs to tell when a women is at her most fertile peak,
and since she‘s willing to have sex at any point in her cycle, he feels compelled
to mate with her throughout that cycle. Furthermore, if he is not around her all
the time, another male might mate with her and distract her resources from
his child.
This need to prevent others from impregnating a woman has even lead to
the evolution of ―sperm warfare‖. As it turns out, only one percent of sperm
are road worthy, while the other ninety-nine, once thought to be defective,
have recently been discovered to be designed to fight other sperm that came
from other men!
Men now have to balance the advantage of having sex with many different
women with making sure that they are actually impregnating them and that
their offspring receive her resources.
By the same token, women too must strike a reproductive balance.
Why Women Cheat
What‘s interesting is that we are socially programmed by our families,
religions, and schools that monogamy is the way to go. Commitment to one
partner is in the interest of the safety and well-being of the children, and for
the most part we do a pretty good job of it. But our selfish genes have their
own means to their own ends.