Chemical fingerprints reveal clues to identity, heterozygosity, and relatedness

Olfaction is a key sense for mammals, and as a result chemical signals are an important means of communication for most mammalian species. It has long been established that most mammals make, distribute, and respond to chemosignals in a range of contexts, including reproduction, parent–offspring interactions, and social relationships (1). However, most aquatic mammals are unable to use olfaction when foraging, and evidence for its role in social behavior has been equivocal. Historically, reports in the literature have ranged from describing the semiaquatic pinnipeds as microsmatic (2) to those that have observed the high prevalence of naso-nasal inspection during social interactions (Fig. 1), and so inferred an important role for olfactory recognition (3). It is only recently that we experimentally confirmed in wild Australian sea lions that olfactory cues are a reliable mechanism in offspring recognition even in the absence of other sensory cues (4). Similarly, new experimental evidence in other large, wild mammals indicates the importance of olfactory cues in discrimination of potential mates and competitors as well as kin (5⇓–7). However, perhaps due to both the complexity of working with natural vertebrate populations and the complexity of vertebrate scents, the mechanistic basis of chemical communication has received little study (8). In PNAS, Stoffel et al. (9) provide an important advance in the understanding of chemical communication in wild mammals. They compared genetic similarity and the chemical profiles of Antarctic fur seals in two colonies. In so doing they revealed that individual-specific chemical fingerprints have both inherited and environmental components and seem to encode mother–offspring similarity, heterozygosity, and genetic relatedness. The implications of these findings for chemical communication in wild mammals are profound.2 page(s