As you go further up the complexity of the animal kingdom you find that there is less and less spreading of seed by the males as the females give birth
to increasingly dependent young. By the time you get to humans at the top of the complexity scale and at the extreme end of the infant nurturing scale,
you get offspring that are so useless they take years of intense looking after before they are capable of fending for themselves and hopefully
living to reproductive age.
There’s a myth perpetuating in our society that men are “naturally” more promiscuous than women. One of the reasons given for this is that men have evolved to “sow their seed widely” so as to have more children and therefore ensure the continuity of their genes.
I'm never sure whether to pull my hair out in frustration or laugh at the ludicrousness of such as suggestion, which I hear so often, even from intelligent thoughtful people.
The fact is that the “sow seed widely” form of reproduction is generally only practiced by the lower orders of animals, such as amphibians and fish and coral. In these species the female lays huge quantities of eggs, which hatch into offspring, most of which don’t survive until reproductive age. The males conversely, have to spread huge amounts of sperm around, to catch the widely scattered eggs.
The reason that human infants are so helpless in the beginning is that they have such huge brains that they have really big heads, and the baby has to be born before its head gets so big that it can’t get out of the womb through the birth canal. So babies are born when their large brains are still relatively undeveloped. They require years of care until their brains have developed to a point where they can fend for themselves (around seven years of age).
Now, given that there were no single mother benefits in prehistoric days, it would have been virtually impossible for a woman to raise children on her own. The human race would not have become as successful as it has if the men were wandering around impregnating women randomly and leaving them to fend for themselves.
No, rather, both parents were required to work together to provide for themselves and their family. In fact, the whole group would have helped in child rearing. When you look at hunter-gatherer societies it’s very much the whole tribe looking after the children, because the tribe needed the children to survive in order for the tribe to survive. Humans are a very cooperative bunch. We've had to be. It’s our ability to cooperate that has enabled us to become so successful as a species - especially given our pathetically useless young!
The result is that humans have evolved (or been designed) to have frequent and highly pleasurable sex so that the parents can feel good about staying together as they need to stay together for the sake of the children. If sex was just about reproduction then women would only be attractive to men when they were ovulating, and there would be no need for either sex to have enjoyable sex (as is the case with almost all other species).
All of which doesn’t deny that there are still highly promiscuous men. The point is though, that they can’t use the “sowing the seed” theory as their excuse!