No, You Absolutely Cannot Impregnate 100 Women in 100 Days

The science behind this male promiscuity myth

There’s this weird myth going around related to how men are evolutionarily designed to “spread their seed.” It says that we know men are biologically designed for promiscuity because a man could impregnate 100 different women in 100 days. But what the actual science around that indicates is that a man is more likely to be killed by a meteor than for this to actually happen. In fact, almost no men sire more than about 12–16 children in their lifetime, only slightly higher than the average possible for women, which is 9–12.

Let’s take a look at this assertion, which is kind of a strange one in the first place, and I’ll show you why a man isn’t likely to impregnate 100 women in his lifetime, much less in 100 days.

The idea comes out of the notion that a woman can only have one baby per year, but that a man has “unlimited” semen that cost him almost nothing from a biological standpoint to produce. But what this fails to take into account, is that the man is not the only person in this equation. Aside from all the costs of time and money that might potentially go into any given seduction, copulating with fertile females is neither easy, nor without costs of other sorts — for humans, or for animals.

In a traditional or indigenous society where women are generally not using birth control, a good portion of the fertile women are either pregnant or nursing much of the time. Paleolithic woman would nurse a child for at least 4 and sometimes as long as 6 years. If there are 100 women in your community, probably 20% of them have not yet reached menarche and 20% are in menopause. That generously leaves you a pool of about 60% of the women. If 80% of that number (48 women) are either currently pregnant or nursing, that knocks your potential numbers down another considerable way — leaving you only 12 possible candidates to impregnate.

Of the women who are left, you have to find ones who are available to you (not in other relationships), who are interested in you (not a given), and who are currently ovulating. This shrinks your chances down to almost infinitesimal numbers.

As University of Notre Dame anthropologist Augustín Fuentes warns: The use of unrealistic figures of potential male reproductive success is counterproductive because there is no evidence that in humans or other primates such a dramatic lifetime reproductive skew occurs with any regularity in any population studied. Using such assumptions as a jumping off point, even if hypothetical, lays an unrealistic baseline that can then be used to create a variety of scenarios, all of which are faulty given the erroneous basal assumption.20

Or to put it a little less academically: Best of luck, Evolutionary Psychology Fantasy Man. (emphasis mine)

Fine, Cordelia. Testosterone Rex: Myths of Sex, Science, and Society (pp. 51–52). W. W. Norton & Company. Kindle Edition.

A sultan with a large harem might be able to accomplish this feat, but the average man has almost no chance of making it happen. In fact, a monogamous man repeatedly sleeping with the same partner has a much higher chance of producing offspring than a promiscuous man. And, in the days before Tinder, how were you even going to meet and woo all of these hundred women, even if you happened to live in a large city and not a small hunter-gatherer band, the way our Paleolithic ancestors did?

In short, fathering anywhere remotely close to a hundred babies a year just isn’t something that any old Stone Age Tom, Dick, or Harry could have achieved. (Indeed, a promiscuous man would need to have sex with more than 130 women just to have 90 percent odds of outdoing the one baby a monogamous man might expect to father in a year.)

Fine, Cordelia. Testosterone Rex: Myths of Sex, Science, and Society (p. 51). W. W. Norton & Company. Kindle Edition.

Even before I saw the numbers crunched, the whole idea of this just kind of made me laugh. Yeah, in theory, the moon is made of blue cheese, but it’s not remotely likely to dress your salad anytime soon. This myth is just another function of an androcentric outlook that refuses to take women into consideration in any substantive or meaningful way, even though you do pretty much need one in order to produce offspring.

Regardless, timing one hundred seductions so precisely would normally be beyond demanding. Even allowing that this remarkable feat could conceivably (sorry!) be pulled off, the chance of producing a hundred children is still only 0.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000748.13

To put that number in a little context, a man’s odds of being killed by a meteorite in his lifetime is 0.000004.14

On average, then, a year of competitive courtship would result in only about three of the one hundred women becoming pregnant.

Fine, Cordelia. Testosterone Rex: Myths of Sex, Science, and Society (p. 50). W. W. Norton & Company. Kindle Edition.

Aside from just the numbers issue, the underlying assumptions are also not in line with how mating actually works. What current science tells us is that in many, many instances mating females are promiscuous and that this is a sound evolutionary strategy, resulting in a greater chance of healthy offspring. And in at least under some conditions, males are actually quite choosy and reluctant to just indiscriminately “spread their seed.”

“The new research helps to understand when and why male choosiness evolves” says academy researcher Mikael Puurtinen. “By modelling a system where females can mate multiply to enhance fertility, and males compete for fertilization of female eggs, researchers show that male choosiness readily evolves. When females mate with many males, the value of matings diminishes for males. By discriminating among females, and prudently allocating their resources, choosy males can have an evolutionary advantage.” he continues. (source)

Darwin first proposed this notion about choosy females and randy males, clearly without ever studying primates in depth because primate females are notoriously sexually promiscuous.

Even supposedly “monogamous” gibbon females hook up with new males when their mates are out of sight. Small summarizes that a thirst for novelty is the single most observable trait among all the sexual behaviors, preferences, and drivers of female primates. In fact, female primates couldn’t be further from reluctant breeders or seekers of “intimacy” with a single “best” mate, or dead set on doing it with “the alpha.”

Martin, Wednesday. Untrue (pp. 164–165). Little, Brown and Company. Kindle Edition.

Darwin’s theory was purportedly scientifically confirmed in 1947 by Angus Bateman’s study on fruit flies. Bateman’s conclusions still loom large in the popular imagination, even though they have been scientifically discredited time and again because of flawed methodology resulting in biased results. The problems with his studies were glaring but they told a story that fed into a predominant cultural narrative, and his work kept being passed along as correct.

“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 who evaluated and were not able to replicate Bateman’s work noted, “We argue that human mating strategies are unlikely to conform to a single universal pattern.” This is something that is born out time and again in actual studies of both human and animal mating. For humans, culture makes a big impact, but other ecological conditions might also. This myth about males being evolutionarily “designed” to be promiscuous when females are not is more of a commentary on our culture than anything else.

If Bateman’s conclusions about sex roles and sexual selection, and science and popular culture’s embrace of it, read like a suspiciously wistful and retroactive justification narrative in which males are active doers, competing and winning and losing and striving and eager to spread their seed and then bolt, as passive, coy, choosy females rain on their collective parade and try to get them to be true while expecting never to pay for their own drinks, that’s because it is. As real gains in equality put women in charge of their reproduction, their earnings, and their destinies more generally in the last decades of the twentieth century, Bateman’s ideas would be periodically reactivated like a virus by anxiety about social change. Wherever and whenever women were independent and in little need of being protected and provided for, the notion that they should passively choose the one most powerful male to safeguard and provision them, and all that it implied about femaleness versus maleness, would be aggressively promulgated by a range of scientists, writers, and politicians whose interests it served.

Martin, Wednesday. Untrue (p. 134). Little, Brown and Company. Kindle Edition.

© Copyright Elle Beau 2023