According to a new study of one of humanity’s closest relatives social cohesion and connection decline in an ageing population. For decades, researchers have been observing the rhesus macaques on Cayo Santiago (known as ‘Monkey Island’) in Puerto Rico. Recent research showed that female macaques “actively reduce” the size of their social networks and prioritise existing connections as they age – something also seen in humans. The paper, published in the journal Philosophical Transactions of the Royal Society B, is entitled: ‘Ageing in a collective: the impact of ageing individuals on social network structure’. The new study, by an international team led by the University of Exeter, examines how this affects the overall cohesion and connection of the groups older monkeys live in. While the observed macaque populations (which had no more than 20% “old” individuals) were not affected at the group level, computer simulations showed higher proportions of old macaques would reduce cohesion and connection. “For both humans and macaques, focusing on close friends and family in later life may bring a variety of benefits,” said Dr Erin Siracusa, from Exeter’s Centre for Research in Animal Behaviour. “Our study aimed to find out what knock-on effect these individual age-related changes have for how well-connected society is overall.