Based on what - other than your say so? Haven't you learned by now that I always have plenty of data and evidence to back up any assertion that I make?
Prior to patriarchy, which arose 6-9 thousand years ago, sexual exclusivity was almost non-existent. Lineage went through the mother so it was fairly irrelevant who the father was. Genetic diversity is in our evolutionary best interests. The cervix is an organ that sorts sperm for health, gentic compatibility, etc. - sort meaning to sift through a variety of available options. That's not it's only job, but it is one of it's primary functions. The coronal ridge of the human penis is shaped that way in order to displace the sperm of other men that may be present in the vagina. Men go flaccid after ejaculation in order to not displace their own semen.
“Besides the fact that many people who ostensibly believe in monogamy engage in extramarital sex (somewhere between 20–60% of Americans, depending on who you ask), many other cultures don’t view sexual exclusivity as normal or necessary even though they have some form of marriage. “Quite apart from promiscuous individuals, there are plenty of societies for which monogamy is not the norm — some estimates place the figure as high as 83%.” Source
This suggests that the value we place on monogamy is more cultural than biological and that it is not the timeless, natural state of affairs that we may have been led to believe. “In the animal kingdom, monogamy in the strictest sense of sexual exclusivity is largely a myth.” Source Why should it be any different for humans?”
