Lack of evidence for pheromones in lemurs.

As chemicals that elicit unlearned, functionally specialized, and species-specific responses [1] or 'stereotyped behavior' [2], pheromones differ from mammalian scent signatures that comprise complex, variable mixtures, convey multiple messages via learned chemical combinations, and elicit generalized responses [1]. Studying ring-tailed lemur (Lemur catta) behavior and semiochemistry, a recent study by Shirasu, Ito et al. [2] claimed to have identified "the first sex pheromones in primates." However, reliance on one male in most chemical procedures and on few females in behavioral procedures constrains statistical analyses and challenges the broad applicability of their findings. Also, the non-independent testing of even fewer signaler-recipient dyads downplays the critical role of learning and memory in primate communication [1] - an argument that refuted earlier claims of primate pheromones [3,4]. Here, we challenge each of their four highlighted findings and interpretations.