Comparative chemical analysis of body odor in great apes

Olfaction is important across the animal kingdom for transferring information on e.g. 18 species, sex, group membership or reproductive parameters. Its relevance has been 19 established in primates including humans, yet research on great apes still is 20 fragmentary. Observational evidence indicates that great apes use their sense of smell in 21 various contexts, but the information content of their body odor has not been analyzed. 22 Our aim was therefore to compare the chemical composition of body odor in great ape 23 species, namely Sumatran orangutans (Pongo abelii (Lesson, 1827), 1 adult male, 5 24 adult females, 4 non-adults), Western lowland gorillas (Gorilla gorilla gorilla (Savage, 25 1847), 1 adult male, 2 adult females, 1 non-adult), Common chimpanzees (Pan 26 troglodytes (Blumenbach, 1775), 4 adult males, 9 adult females, 4 non-adults) and 27 bonobos (Pan paniscus (Schwartz, 1929), 2 adult males, 4 adult females, 2 non-adults). 28 We collected 195 samples (five per individual) of 39 captive individuals using cotton 29 swabs and analyzed them using gas chromatography – mass spectrometry. We 30 compared the sample richness and intensity, similarity of chemical composition and 31 relative abundance of compounds. Results show that species, age and potentially sex 32 have an impact on the variance between odor profiles. Richness and intensity varied 33 significantly between species (gorillas having the highest, bonobos the lowest richness 34 and intensity), and with age (both increasing with age). Richness and intensity did not 35 vary between sexes. Odor samples of the same species were more similar to each other 36 than samples of different species. Among all compounds identified some were 37 associated with age- (N = 7), sex- (N = 6), and species-related (N = 37) variance. Our 38 study contributes to the basic understanding of olfactory communication in hominids by showing that the chemical composition of body odor varies across species and 40 individuals, containing potentially important information for social communication