Lemur Olfactory Cues

Scientists at Duke University in Durham, North Carolina, USA, have discovered that olfactory cues can indicate pregnancy and foetal sex in the ring-tailed lemur (Lemur catta).¹ Using gas chromatography coupled to mass spectrometry (GC–MS), the team found that lemurs carrying male offspring exhibited a different volatile chemical profile to those carrying a female.

Olfactory cues play an integral role in facilitating social and reproductive behaviour in vertebrates. These cues fluctuate with hormonal condition, such as puberty, change in season, and, in females, timing of ovulation. Christine Drea, professor of evolutionary anthropology and corresponding author, told The Column: “The role of odour in primate evolution, including in humans, is underappreciated. Currently, how we formulate hypotheses about signals or communication and how we interpret relevant data is heavily biased by information available to us via the visual sense. If we don’t “see” a signal, we tend to think the information doesn’t exist.”

The test subjects were 12 sexually mature female ring-tailed lemurs that were monitored over a six-year period (including 14 pregnancies). Samples were taken from secretions before conception and during pregnancy and were analyzed by GC–MS. Christine commented: “We selected GC–MS because of the nature of the secretions from lemur glands, including genital, which tend to contain greasy, higher molecular weight compounds. GC–MS seems to capture a good range of the compounds expressed (although we know it doesn’t capture everything).” It was found that the odourant profiles of the lemurs changed with pregnancy, relative to preconception; pregnancy was associated with a significant decrease in the total number of volatile compounds expressed. This change was even more profound in those lemurs carrying male offspring with volatile compounds being further reduced in these samples. The researchers determined that the degree to which compounds are lost during pregnancy and influenced by foetal sex was inversely related to the subject’s sex steroid concentrations. These findings suggest endocrine involvement in the production of olfactory gestational cues.These olfactory cues may help guide social interactions, promoting mother–infant recognition, reducing intragroup conflict, or counteracting behavioural mechanisms of paternity confusion.

The team will continue their work with lemurs. “We’ve worked quite a bit on lemurs, focusing on the various kinds of information (for example, species, sex, reproductive state, ID, quality, etc) contained in an individual’s scent,” Christine said. “Now, we’re zooming in a little further on the microbial contribution to lemur odours. Basically, we’re asking what role the bacteria that live on an animal’s body play in influencing that animal’s perfume, through such processes as fermentation. It is likely that this avenue of research will provide a link for how one’s health might be communicated through odours.” - K.M.

Reference
1. Jeremy Chase Crawford and Christine M. Drea, Biology Letters 11(2), 20140831 (2015).

This story was first featured in LCGC's digital magazine, The Column. Click here to view the full issue>>

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