Researchers at the University of Exeter propose that having friends and enemies makes evolutionary sense among the animals that age slowly and live for many years. The scientists argue that natural selection favors complex social structures and relationships in long-lived animals.
Animals that live fast and die young focus their energy on reproduction, while animals that age much more slowly invest in survival and live longer lives.
For long-lived animals, knowing their friends and enemies comes more easily, and helps them to live even longer. Animals that live and die at a fast pace, however, should only bother with social relationships if it increases their chances of reproduction, explained the researchers.
“Slow-living species can afford to invest in social relationships, as they live long enough to enjoy the pay-offs,” said Professor Dave Hodgson. “There is strong evidence that strong social bonds are beneficial for survival in slow-living species, including humans.”
“We suggest there is a ‘positive feedback’ – certain social behaviours lead to a longer life, and longer lifespan promotes the development of social bonds.”
Professor Hodgson said there is growing evidence that differentiated social relationships have a stronger supportive effect on survival than on reproduction. As a result, fast-lived species do not gain the same evolutionary advantages from social relationships as long-lived species.
“If we want to understand more about social relationships and lifespan, we need to think about the relationship between the two,” said Dr. Matthew Silk. He noted that further research is needed to explore the social structures of wild animals, and could help to clarify the links between social bonds, survival and reproduction.
“Our proposal, that strong and weak social bonds will be more prevalent in slower-living animals, is theoretical,” said Professor Hodgson. “We know a lot about animal lifespans, but we know too little about the social structures of many types of animal. If we are right, then social bonds could really be key to longer life.”
The study is published in the journal Trends in Ecology and Evolution.