Forbidden Fertility

Human conscious minds seem unaware of many important functions of human behaviors. Humans don’t know how they breathe, digest food, or stand without falling. But conscious attention is expensive, and there seems little to be gained from conscious minds managing such processes. Also, large system changes would be required to add control and sensory neurons in order to enable such conscious management.

However, humans also seem unaware of other important behaviors where more can be gained from conscious management, and where brains already seem to have something close to the required control and sensory connections. People don’t seem to know why they laugh, why they like the folks they like, or why they go to school or the doctor. Humans are unaware of their constant status moves, and are largely unaware of their overconfidence.

Now some argue that there is also little to be gained by conscious awareness of such things; the unconscious mind manages such things just fine. But if so, the conscious mind begins to look irrelevant; what should we expect the conscious mind to be aware of, if not such things?

One story is that consciousness is the mind’s public relations department, charged with managing our words and the actions we most coordination with our words, in order to present a good face to others. Given this theory, we should be surprised to see conscious minds unaware of things close to the content of their words, and to the actions their words coordinate.

For example, we should be surprised to see people unaware of their overconfidence, status moves, or tendency to mimic others to be liked. People vigorously deny the existence of such things, and are eager to explain suggestive evidence in other ways. Such unawareness seems better explained via motivation – it seems to be in our interest to remain unaware of such things, in order to present a more convincing face to others. Our minds may be designed to prevent conscious awareness of many such things.

One of our most puzzling unawareness is of fertility. In most primate species, female bodies clearly advertize when they are fertile, and males seem quite aware of such clues, which influence male plans and activities in big ways. Human female bodies, in contrast, do not so advertize, and human males and females say they are unaware of but the most obvious clues (e.g., discharges). In fact, the standard theory until recently was that there were no other such clues, that human female fertility is hidden. But in fact we’ve learned that not only are there many strong clues, both men and women are unconsciously quite aware of such clues, which strongly influence their behavior!

For example, a recent study paired random men and women for a few minutes. Even though “neither objective coders nor the participants themselves perceived any changes in the [female] confederate’s overt behavior across the menstrual cycle,” men were four times more likely (63% vs 15%) to mimic the woman when she was fertile:


Fertility is important, seemingly the sort of thing people would want to talk about and integrate with the actions that they coordinate closely with their words. Yet relative to other primates, humans have not only lost their big overt signs of fertility, our verbal selves seem completely unaware of other fertility clues, even as our actions strongly react to them! Why couldn’t men profitably talk about which women around them are fertile, and integrating such knowledge into their verbally coordinated plans? “George may not want to join us Saturday, as his girlfriend should be fertile then.”

Could motivated unawareness explain this?  Might it just look bad for men to attend to female fertility, so very bad that men have completely repressed their fertility knowledge, for fear of showing such attention? But men are usually eager to show their sexual sophistication; why the sudden eagerness to appear naive? What bad feature of a man could correlate so strongly with knowledge of fertility?

One possibility is that women want to keep their fertility info private, to give an advantage to men who are socially close to them, relative to distant men. They would then discourage public conversation on who is fertile when. But in this case close men would want to signal their closness to a woman via their knowledge of her fertility.

Another possibility is that a short term mating focus looks bad. Long term mates should be less concerned to discern fertility, if they expect to consistently mate over the entire fertility cycle. But men and women are both capable of and practice short term mating strategies, and both are often eager to signal their ability and inclination toward such strategies to desirable partners. If “cads” distinguish themselves from “dads” by acting rebellious and aggressive, why wouldn’t cads also distinguish themselves via fertility awareness?

A third possibility is that ancestral woman really disliked male mate guarding. Insecure possessive mates might tend to 1) guard females more, 2) attend more to female fertility to support such guarding, and 3) be less desirable as mates. Women would then avoid men who visibly attended to fertility. This correlation could apply to both short and long term mates; a woman might prefer a long term mate secure about her faithfulness, and a short term mate willing to leave peacefully when she is done with him.

This last theory supports Sex At Dawn‘s story of ancestoral promiscuity. But it also suggests that women now remain averse to men who show extra interest in their fertility cycle, and women just don’t report much aversion of this sort.

OK, I’m somewhat stumped – any other theories to consider?

More quote on fertility:

Subtle cues of fertility prime mating motivation in men, thus facilitating psychological and behavioral processes associated with the pursuit of a sexual partner. … Men exposed to the scent of a woman near peak levels of fertility displayed increased accessibility to sexual concepts. … In a face-to-face interaction, high levels of female fertility were associated with a greater tendency for men to make risky decisions and to behaviorally mimic a female partner. …

During the few days when conception risk is highest, for example, women report increases in sexual self-stimulation, overall sexual desire, and number of sexual fantasies. Women also report greater interest in activities associated with finding and attracting new romantic partners, such as attending social gatherings and wearing more sexually provocative clothing. During peak fertility, women show a particular preference for men displaying indicators of good genes …

Men tend to rate certain characteristics of women (e.g., their scent, their voice, their face) as most attractive during periods of peak fertility.  … Women report heightened mate-guarding behaviors (e.g., possessiveness and monopolization of the women’s time) by their male romantic partners during periods of peak fertility. … Female dancers received greater tips from men when near ovulation. …

Women, unlike the females of many other species, do not exhibit highly overt physical indicators of fertility, such as the sexual swellings that appear on the hindquarters of other primate females. Consequently, for quite some time, scientists presumed that women’s ovulation was concealed. However, an emerging body of evidence suggests otherwise. … Men subjectively evaluate the odors of women close to ovulation as more pleasant-smelling. … Shifts in women’s facial skin tone, vocal pitch, body symmetry, and waist-to-hip ratio have all been linked with shifting fertility levels.  …

The extent to which a woman’s fertility status elicits a man’s mating behavior may depend on the man’s orientation toward short-term versus long-term mating, whether the people are already committed to a long-term relationship, or the availability of other potential partners in the community. …

Neither participants nor objective coders noticed differences in the confederate’s behavior as a function of her fertility status, and participants rated her level of flirtation as quite low. … We suspect that men are not consciously aware of the degree to which their attraction is influenced by subtle fertility cues such as scent. (more)

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