Taken in tandem with body language and scent-marking, this range of expression allows ring-tailed lemurs a complexity of social interaction that was once held to be the preserve of “higher” anthropoid primates – that is, monkeys and apes. Indeed, studies of anti-predator warning strategies among ring-tailed lemurs have revealed that they employ a specific vocabulary to distinguish between threats. Thus shrieks warn of a passing Madagascar buzzard or another bird of prey, while yaps are used when mobbing a predatory mammal, such as the mongoose-like fosa.

Learning the language of ring-tailed lemurs helped Jolly and her colleagues to unlock the secrets of their social life. It turned out that, in contrast with monkeys and apes, the lemurs live in a matriarchal society. While both males and females have separate dominance hierarchies within their sex, all females enjoy dominance over all males – a status that they readily assert by cuffing, lunging, biting and other displays of force.

Females stick together in their natal groups, with one high-ranking alpha female providing the central point for the group. Being the dominant sex, they maintain the groups territory – a fairly loose home range that overlaps with that of other groups. They will also take the lead in confrontations, driving off intruders with stares and other ritualised expressions of hostility. These interactions seldom lead to violence. Within their own troop, however, female dominance battles can turn ugly, resulting in serious injury or even expulsion.