The Nonattachment Hormone

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Science  18 Nov 2005:
Vol. 310, Issue 5751, pp. 1114
DOI: 10.1126/science.310.5751.1114c

In 95% of mammalian species, males never bond with mates or help raise young. So what makes men inclined to roost and nurture? Testosterone seems to play a role.

Although high levels are associated with aggressive behavior in animals, they plummet with parenting in some species. Studies in North American males suggest the same trend in humans. Now comes evidence from China that this holds true regardless of culture. A team led by Peter Gray, a biological anthropologist at the University of Nevada, Las Vegas, recruited 66 bachelors, 30 married men without children, and 30 married fathers aged 21 to 38 in Beijing who twice a day provided saliva for testing. Compared with bachelors, childless husbands had about 20% lower levels of the hormone in the morning (when levels are highest), and married fathers had almost 50% lower levels. Smaller but significant differences showed up in afternoon measurements, the team reported last week in Proceedings of the Royal Society: B.

Psychologist Nick Neave of Northumbria University in Newcastle-upon-Tyne says the findings make sense because testosterone is related to “a host of sexual behaviors intended to attract a mate [but which] are not conducive to marital bliss and especially not when very young children are present.” He adds: “It would be interesting to see if testosterone levels are associated with poorer male parenting skills.”

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