New theory on why male, female lemurs...( When it comes to investigating myste...)

When it comes to investigating mysteries, Sherlock Holmes has nothing on Rice University biologist Amy Dunham. In a newly published paper, Dunham offers a new theory for one of primatology's long-standing mysteries: Why are male and female lemurs the same size?

In most primate species, males have evolved to be much larger than females. Size is an advantage for males that guard females to keep other males from mating with them, and evolutionary biologists have long wondered why lemurs evolved differently. Some theories have suggested that environment played a role or that lemur social development was altered due to the extinction of predatory birds.

"Scientifically, this is quite a big question that researchers have debated for over 20 years," said Dunham, assistant professor of ecology and evolutionary biology. "I actually started doing research on lemurs as an undergraduate, working in Ranomafana (National Park in Madgascar), and the question about size monomorphism has bugged me since then."

In a paper featured on the cover of this month's Journal of Evolutionary Biology, Dunham offers one of the first new theories on lemur monomorphism in more than a decade.

After an exhaustive review of the observational work done on lemurs, Dunham came to the conclusion that male lemurs do guard their mates, just like other primates. But unlike gorillas and other primates that fight for mating rights with females, male lemurs have evolved to passively guard their mates.

They do this by depositing a solid plug inside the female's reproductive tract just as they finish mating. The plug is deposited as a liquid protein but quickly hardens and stays in place for a day or two. Since many female lemurs are sexually responsive to males for only one day out of the entire year, the plug serves the purpose of preventing other males from mating with the female, while also freeing the male to mate with other females during the br
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