VSL:SCIENCE // News flash: Males who move in with their mates are manlier

According to a recent study by Penn State geneticists, male mice that live with females are measurably “manlier” than male mice that live alone.

The researchers tracked testis size, testosterone levels, and other fertility measures and discovered that males living with females fathered more children during mating periods, had more testosterone, and stayed fertile longer. (In case you’re wondering, mice hit middle age at 16 months.) And while all the males’ testes shrank as the mice aged, the bachelors’ testes shrank a bit more. According to the study, the findings have significant implications for “wildlife, livestock, and human populations.” We’re pleased, we think, to see ourselves on the list.

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