Who will make a good father?
Highlights two successful but opposite evolutionary strategies for parental care.
Dec 12th 2015 | Economist
MEN want sex and sex leads to fatherhood. If these two statements were propositions in a syllogism, then the logical conclusion would be that men want fatherhood. Observation, however, indicates that this is not always the case. As the number of women left, literally, holding the baby shows, quite a few men run a mile from fatherhood.
Of course, the statements are not part of a syllogism, for the word “fatherhood” has different meanings in the first sentence and the second and third ones—the first meaning is biological and the second social. Moreover, there are quite a few men who do not run a mile from the social form of fatherhood. And Dario Maestripieri of the University of Chicago thinks he has found a way to tell doting dads from deadbeats in advance: check a man’s reaction when he watches a smutty movie.
The reaction Dr Maestripieri monitored was the viewer’s testosterone level, before and after. This he compared, as a control, with the same man’s responses, on a different day, to mock job interviews and mental-arithmetic tests.
This study was a follow-up to one in which Dr Maestripieri had tested the existing theory of who makes a good dad, and found it wanting. This is that the more testosterone a man has, the less likely he is to hang around to help bring up baby. Using a questionnaire which asked things like, “How much do you like babies?”, “Do you think most babies are cute?” and “Do you want to have children someday?” Dr Maestripieri showed that the answers are uncorrelated with a man’s testosterone level, as measured from a saliva sample. Good news, then, for women who would like to settle down with a hunk, but fear hunks are not the settling-down sort. But there is still the question of which hunk to choose—and that is where the movie (an attractive young lady performing a striptease, and then masturbating) comes in.
Dr Maestripieri’s volunteers, who were 107 young, unmarried, heterosexual men, duly filled in the questionnaire and gave their before and after samples of saliva, and Dr Maestripieri and his colleagues found what they were looking for. As they report in Psychological Science, they discovered that if a man scored a -3 on the baby questionnaire (which ran from -6, indicating no interest at all in babies, to +6, indicating a heartfelt love for changing nappies) he was likely to have experienced an increase in testosterone of 20 picograms per millilitre of saliva during the video. In contrast, the testosterone of a man who scored +3 was unlikely to increase at all. And, in the case of one participant who scored a +6, his testosterone level actually dropped by 10 picograms per millilitre during the showing. In contrast (and as expected), there was no correlation between attitudes to babies and any changes in testosterone levels that took place following the mock job interview and the arithmetic task.
Crucially, too, the team confirmed their earlier result that men’s pre-video testosterone levels are uncorrelated with their attraction to babies, as measured by the questionnaire. And by giving the volunteers a second questionnaire to fill in, the researchers also dug a bit into what might be going on behind the biological scenes, to explain the differences they had found.
The second questionnaire, called the Mini-K test, measures how socially embedded an individual is, by asking him to rate his response to propositions such as, “I have to be closely attached to someone before I am comfortable having sex with them”, “I avoid taking risks” and “I often get emotional support and practical help from my blood relatives”. The “K” in the test’s name is a term ecologists use to describe natural selection that favours small, stable families and lots of parental care. (The opposite, r-selection, favours many offspring and little or no parental care.) The Mini-K has long been used by psychologists to tease out whether an individual is someone predisposed to living a settled life involving marriage and children, or is prone to living life in the fast lane with frequent flings and little commitment.
Unsurprisingly, the Mini-K results also correlated with the response to the video, confirming the idea that changes in testosterone levels do indeed, at least superficially, match the r-K continuum. That makes some sense in evolutionary terms. A man who takes an “r” approach to life is likely to have more children (assuming he survives, for he is also more likely to provoke hostility), but they will be less well looked after and probably more likely to die. The “K” approach will sire fewer babies, but they will be well nurtured and tend to survive. Several generations down the track, therefore, genes for both strategies may do equally well.
Even more likely, though, is that r-type and K-type responses develop in reaction to childhood experience, for (and this idea is again borrowed from ecology) “K” will do well in settled environments and “r” in unpredictable ones. But testing that idea will be both difficult and controversial.
On the more immediate question, though, of how a woman can tell whether a man is a potential “keeper” or not, this work does provide a convenient answer. All you have to do is show him a dodgy video and get him to spit in a pot.
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