Looking at sexual mores in a Western patriarchies (which are only a few thousand years old) and then deciding those describe "natural" human mating habits is kind of the dictionary definition of poor scientific method.
In truth, this ought to be enough right there. If sexual monogamy were “natural” and something that most people were innately inclined to, we would never have had or needed the social and sexual control of women that only arose 6–9 thousand years ago. But even beyond this, there are other ways that we know that sexual monogamy is a relatively new human expectation.“
A female who mates with several different males will have more genetically diverse offspring, boosting the chances that at least some of them will thrive.” Source
This goes for human females as well as other non-human animals and it is confirmed in the anatomy of both human men and women.
The coronal ridge of the human penis is specifically shaped to displace semen left there by another man or men. In addition, animals that engage in mate competition prior to copulation (like gorillas) tend to have small testes and penises. Animals that instead engage in sperm competition are more well endowed relative to body size (like chimpanzees and humans) because they need to have a large supply of semen on hand to inseminate multiple partners.
The myth of the coy and chaste female is all but shattered. We now know that in most animals females are surprisingly promiscuous.
Bateman’s experimental study of Drosophila melanogaster produced conclusions that are now part of the bedrock premises of modern sexual selection. Today it is the most cited experimental study in sexual selection, and famous as the first experimental demonstration of sex differences in the relationship between number of mates and relative reproductive success. We repeated the experimental methodology of the original to evaluate its reliability. The results indicate that Bateman’s methodology of visible mutations to assign parentage and reproductive success to subject adults is significantly biased. Source
“Here was a classic paper that has been read by legions of graduate students, any one of whom is competent enough to see this error,” Gowaty said. “Bateman’s results were believed so wholeheartedly that the paper characterized what is and isn’t worth investigating in the biology of female behavior.”“Our worldviews constrain our imaginations,” Gowaty said. “For some people, Bateman’s result was so comforting that it wasn’t worth challenging. I think people just accepted it.” Source
As another group of researchers noted, “We argue that human mating strategies are unlikely to conform to a single universal pattern.”
