Female African elephant rumbles differ between populations and sympatric social groups.

Vocalizations often vary in structure within a species, from the individual to population level. Vocal differences among social groups and populations can provide insight into biological processes such as vocal learning and evolutionary divergence, with important conservation implications. As vocal learners of conservation concern, intraspecific vocal variation is of particular interest in elephants.

African elephants address one another with individually specific name-like calls.

Personal names are a universal feature of human language, yet few analogues exist in other species. While dolphins and parrots address conspecifics by imitating the calls of the addressee, human names are not imitations of the sounds typically made by the named individual. Labelling objects or individuals without relying on imitation of the sounds made by the referent radically expands the expressive power of language.

Wild acorn woodpeckers recognize associations between individuals in other groups.

According to the social intelligence hypothesis, understanding the cognitive demands of the social environment is key to understanding the evolution of intelligence. Many important socio-cognitive abilities, however, have primarily been studied in a narrow subset of the social environment-within-group social interactions-despite the fact that between-group social interactions often have a substantial effect on fitness. In particular, triadic awareness (knowledge about the relationships and associations between others) is critical for navigating many types of complex social interactions, yet no existing study has investigated whether wild animals can track associations between members of other social groups.