Penis size does matter for bank voles, says study

The secret to social dominance for bank voles appears to be the size of their genitals, according to scientists.

The link was made by researchers from Europe who were studying the small brown mammals' reproductive behaviour.

The study, in Behavioural Ecology and Sociobiology, found dominant males had wider penis bones, also called baculum.

Although not present in humans, these bones are found in many other species of mammal but their exact function has not been confirmed.

The study was conducted by Dr Jean-Francois Lemaitre from the University of Liverpool with colleagues in France and Switzerland.

Bank voles live for a maximum of 18 months and females give birth to four or five litters per year.

"This species is particularly interesting for study... because females mate with several males during a single reproductive bout," explained Dr Lemaitre.

Researchers suggest that this competition may have driven evolutionary adaptations in genital anatomy to improve males' chances of reproduction.

To test their theory, the team collected wild bank voles in Cheshire and studied their lab-reared offspring to understand which were dominant and which were subordinate.

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By Ella Davies Reporter, BBC Nature