Introduction

The most complex animal societies so far described are found among the social insects and mammals. The individuals in these societies interact via a complex web of semiochemical signals, including the odour signature that gives each member access to the group.

In both mammals and social insects, each individual has a great complex of odours produced by the animal and acquired from the environment and from conspecifics. The resulting chemical signatures of both mammals and social insects are complex and variable mixtures, giving a forest of peaks on a gas chromatograph trace, in contrast to the small number of defined peaks for the sex pheromones of moths and other insects (see Chapters 1 and 2). These complex mixtures reflect the overlaying of many different messages. For example, the saddle-back tamarin (Saguinus fuscicollis) a South American primate, produces chemical messages which identify species, subspecies, individual and gender, and may also contain information on social status (Epple et al. 1993). Social insects carry a chemical message on their cuticle that includes information about their species, colony, caste, age and gender. In both mammals and social insects the cues giving reproductive status, in particular ovarian status, may be the key to the role of pheromones in reproduction in social animals (Section 6.3.2). While signals of caste, gender, life stage or species may not vary much within the species and could thus be said to be anonymous (Hölldobler & Carlin 1987), the variability of colony and kin recognition chemical signatures is what gives them their specificity.