If you’re interested in animal behavior, you’ll likely know that olfactory cues can affect how mammals interact with one another. Previously, we highlighted the “alluring” aroma of blood and its effect on carnivores (read article). Now, after conducting research at Duke University, Christine Drea, Professor of Evolutionary Anthropology, and her student Jeremy Chase Crawford (who has since moved to the University of California) say they can tell whether pregnant lemurs will give birth to a male or female by analyzing the scent secretions of the mother-to-be (1). Drea believes that olfactory cues are often underappreciated, and that their relationship with gestation is poorly understood.
Drea and Crawford collected secretions from ring-tailed lemurs for gas chromatography-mass spectrometry (GC-MS) analysis. They used a measure of “chemical richness” (the number of different chemical compounds) and compared results between nonpregnant and pregnant lemurs. Richness decreased with pregnancy and, importantly, dams bearing male offspring showed a greater decrement in richness than those bearing females, particularly later in gestation.
“It isn’t clear to me yet why dams with sons would show such a decrement. But given how strong the differences are, lemurs in all likelihood can detect them,” says Drea. “If this phenomenon evolved as an adaptation, it would have to confer a benefit to the pregnant female. In this scenario, the pregnant female may use the information about her own scent as a type of self-referent/phenotype matching mechanism, allowing her own body to act on the information provided by these signals, such as continuing to invest in a fetus or to disinvest.”
For Drea’s lab, the latest study was a logical next step in their work; they’ve been studying lemur olfactory communication for quite some time. “The main challenge when working with mammalian odors is that it is very difficult to identify the exact compounds that are responsible for signaling [...] given that each secretion contains hundreds of compounds, in varying proportions, it hasn’t yet been possible to show which ones are responsible for the many pieces of information conveyed,” says Drea.
Could the research have implications for other primates? In principle, Drea believes that fetal sex-differentiated patterns in a mother’s scent could well be present more broadly. Certainly as a diagnostic test, the process is labor intensive, so the work is more relevant to those studying animal behavior; olfactory cues may be linked to promoting mother-infant recognition, reducing intragroup conflict, or counteracting behavioral mechanisms of paternity confusion.
- J. Crawford and C. Drea, “Baby on Board: Olfactory Cues Indicate Pregnancy and Fetal Sex in a Nonhuman Primate,” Biology Letters, DOI: 10.1098/rsbl.2014.0831 (2015).
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