Odor profiles of the genital secretions in mixed-sex pairs of related and unrelated lemurs. Chromatograms of labial (first column) and scrotal secretions (second column) from three female-male pairs of lemurs during the breeding season. Top row: maternal half-siblings, representing a sister (A) and her brother (B). For this pair, DID = 0.28 and DC = 0.47. Middle row: mother (C) and son (D). For this pair, DID = 0.18 and DC = 0.54. Bottom row: unrelated female (E) and male (F) born in different colonies. For this pair, DID = 0.55 and DC = 1.16. The filled arrow points to the internal standard, hexachlorobenzene, added to the sample before the GCMS run and the open arrow points to the endogenously produced standard, squalene.