Lack of evidence for pheromones in lemurs

Reverse Chemical Ecology Suggests Putative Primate Pheromones

Pheromonal communication is widespread among living organisms, but in apes and particularly in humans there is currently no strong evidence for such phenomenon. Among primates, lemurs use pheromones to communicate within members of the same species, whereas in some monkeys such capabilities seem to be lost. Chemical communication in humans appears to be impaired by the lack or malfunctioning of biochemical tools and anatomical structures mediating detection of pheromones. Here, we report on a pheromone-carrier protein (SAL) adopting a "reverse chemical ecology" approach to get insights on the structures of potential pheromones in a representative species of lemurs (Microcebus murinus) known to use pheromones, Old-World monkeys (Cercocebus atys) for which chemical communication has been observed, and humans (Homo sapiens), where pheromones and chemical communication are still questioned. We have expressed the SAL orthologous proteins of these primate species, after reconstructing the gene encoding the human SAL, which is disrupted due to a single base mutation preventing its translation into RNA. Ligand-binding experiments with the recombinant SALs revealed macrocyclic ketones and lactones as the best ligands for all three proteins, suggesting cyclopentadecanone, pentadecanolide, and closely related compounds as the best candidates for potential pheromones. Such hypothesis agrees with the presence of a chemical very similar to hexadecanolide in the gland secretions of Mandrillus sphinx, a species closely related to C. atys. Our results indicate that the function of this carrier protein has not changed much during evolution from lemurs to humans, although its physiological role has been certainly impaired in humans.

Response to Drea et al

We greatly appreciate the critical comments on our paper made by Drea et al. [1]. We would like to emphasize that we are not claiming or giving concrete evidence that the identified compounds are pheromones in our paper. We agree that before we can reasonably conclude that the identified compounds are indeed pheromones, we would at least need to examine whether the responses to the identified compounds are stereotypical and reproducible and exclude the effects of signature differences, such as health, relatedness and genetic quality. To this end, it will be necessary to investigate a broader range of behaviors in the future using a larger number of animals.

Pheromones: Stink Fights in Lemurs

Some primates, in particular lemurs, have long been known to communicate by smell. However, no bona fide primate pheromones have been identified. A recent study of ring-tailed lemurs offers some - disputed - candidate molecules for a male pheromone.