Gender of Unborn Lemurs Determines Mother's Smell

It's an iconic image: a wrinkled great-grandmother hovering over a swollen belly while she dangles a needle on thread. "It's a boy" or "it's a girl," she'd proclaim without any real idea of what she's talking about. Scientists have long argued that there is no sure-fire way to determine an unborn child's gender. Even ultrasound can get it wrong. For lemurs, however, all it might take is a sniff of strong motherly BO. 

That's at least according to a study recently published in the journal Biology Letters, which details how the gender of her unborn child can influence the smell that a pregnant lemur gives off.

So how was this determined? Researchers Christine Drea of Duke University, and Jeremy Chase Crawford, of the University of California, collected scent secretions from 12 female ring-tailed lemurs at the Duke Lemur Center in Durham, N.C.

These samples came straight from the musky ooze that female lemurs sometimes release from their genital regions, which could help friends and family find and identify them. The secretions were collected twice over the course of the study - once before and once after the mothers gave birth.

By conducting chemical analysis using gas chromatography and mass spectrometry, the researchers were able to identify the hundreds of ingredients that make up each female's scent.

They first found that the scent of females who are not pregnant is far more complex than the odor pregnant mothers release. That might be because this complex cocktail of pheromones is conveying information about health, fertility, and other qualities to prospective mates.

During pregnancy, however, the females still boasted two very different, albeit simple, odors.

"The difference in hormone profiles between pregnant lemurs carrying sons and those carrying daughters is dramatic," Drea explained in a statement.

She added that the odor is at its simplest when a mother is to birth a male.

Drea and her colleagues suggest that this might be due to the fact that pregnancy ties up resources that would have otherwise been used in crafting a complex odor cocktail.

They add that this would be especially true "if it's more energetically costly for a female to have a male pregnancy than a female pregnancy," explaining for the gender-specific odors.

However, more work will need to be done to confirm if that is really the case.

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