Boy or girl? Lemur mom's scent can tell

Pregnant lemurs carrying sons smell different from those carrying daughters, a new study has found.
The results represent the first evidence in any animal species that a pregnant mother's scent differs depending on the sex of her baby, said Christine Drea, a professor of evolutionary anthropology at Duke University.
Drea and co-author Jeremy Chase Crawford of the University of California, Berkeley used cotton swabs to collect scent secretions from the genital regions of 12 female ringtailed lemurs at the Duke Lemur Center in Durham, North Carolina, before and during pregnancy.
Cat-sized primates with long black-and-white striped tails, ringtailed lemurs produce a musky odour.

The distinctive scent is a complex cocktail of pheromones and other chemicals that have been shown by previous studies to convey information about an animal's sex, fertility, and other qualities.
In the new study, chemical analysis using gas chromatography and mass spectrometry revealed the hundreds of ingredients that make up each female's scent change during pregnancy.

Expectant lemur moms give off simpler scents that contain fewer odour compounds compared with their pre-pregnancy bouquet - a change that is more pronounced when the moms are carrying boys, Drea said.
The patterns correlate with changes in blood hormone levels, the researchers found.

Drea said hormones change dramatically during pregnancy, and girls and boys affect their mothers' hormones differently.
"The difference in hormone profiles between pregnant lemurs carrying sons and those carrying daughters is dramatic," she said.
The researchers don't yet know why pregnant lemurs produce simpler scents, particularly when they are carrying sons.
"It could be that producing these compounds uses resources that are directed elsewhere when they're pregnant, especially if it's more energetically costly for a female to have a male pregnancy than a female pregnancy," Drea said.
The study is published in the journal Biology Letters.