Here’s a curious data point for those who are obsessed with plotting their fertility: at their most fertile times of the month, women are half as likely to call their fathers, according to a new study published in the prestigious journal Psychological Science. If women do call Dad during fertile peaks — or if Dad calls them — they keep it short: women stay on the phone with their father on fertile days for an average of 1.7 minutes per call, compared with the comparatively chatty 3.4 minutes they’ll spend when they are not about to ovulate.
Why the aversion to phone calls with Dad? One obvious explanation was ruled out — it’s not that they’re busy with, um, other activities. During their fertile times, women actually had slightly longer phone calls with their mothers, clocking 4.7 minutes per call, compared with 4.2 minutes on other days of the month. (More on Time.com: Battle of the Bris: A Move to Outlaw Circumcision in San Francisco)
The real explanation may lie in our evolutionary history. Because incestuous relationships among primates are less likely to produce healthy offspring, humans develop a natural disgust for opposite sex partners with whom they were raised. Proximity during childhood is a pretty good marker for relatedness and serves to elicit this disgust: in the vast majority of cases, the males around you during early childhood are going to be your father, uncles or brothers. Even if they aren’t, if you are raised in daily, close contact with someone, you’re unlikely to be attracted to him or her— this was found on Israeli kibbutzes and in China, when a custom of adopting young girls as future wives for sons led to marriages marred by mutual sexual disinterest.
Unconsciously, then, women are likely to be predisposed to avoid contact of any sort with close male relatives at times when they are most likely to become pregnant. (It would be interesting to see if the same held true for brothers as for fathers.) Freud got it backwards here: the unconscious inclination is not towards incest, but away from it. (More on Time.com: Girls Want to Talk About Sex — With Dad?)
Evolutionary psychologists get all sorts of grief from critics who claim that they make up “just so” stories to provide biological explanations for things that are better explained by culture or simply cannot be proven. This study, however, leaves little room for anything but an evolutionary perspective.
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