Some Animals Need Both Friends and Enemies to Survive, Study Finds

Animals that live fast and die young don’t really need to worry about long-term relationships. 

These “fast-living” species like shrews and crickets focus most of their energy on reproduction. It doesn’t really matter who else they interact with along the way as long they survive long enough to procreate.

But it’s a whole different story for slow-living species, new research suggests. Larger animals like elephants, whales, and even humans have a slower life pace. They prioritize survival over reproduction. And part of that survival plan is having complex social relationships.

“Social relationships can be important for survival in numerous ways,” study co-author Matthew Silk of the Centre for Ecology and Conservation on the University of Exeter's Penryn Campus, tells Treehugger.

“Good examples would be the buffering effect provided by ‘friends’ that has been shown in studies of various different species to reduce stress levels after aggressive interactions and also to improve health," adds Silk. "Having good relationships with the right individuals can also reduce competition with group mates and make it easier to access food supplies.”

Silk and co-author David Hodgson, also of Exeter, published their work in the journal Trends in Ecology and Evolution.

The Benefits of Relationships

The researchers suggest slow-living species can afford to invest in social relationships because the payoffs are worth the time. 

“In the paper we argue that in general because slow-lived species are more likely to gain these benefits because their long lifespans give time for the benefits to accrue over time — it might take a while to form a strong relationship meaning the benefits are delayed,” Silk says.

The researchers give examples of hyenas, which are slow-living animals. They live in complex social groups called clans, where there are complicated systems of hierarchies and relationships, play a key role in conflicts.

Hyenas that form alliances with other friends and allies are likely to improve their position and move up in the hierarchy. Having a high rank gives animals access to the best resources which obviously helps with survival.

"We suggest there is a 'positive feedback' — certain social behaviors lead to a longer life, and longer lifespan promotes the development of social bonds,” Hodgson said in a statement.

There might be other traits of slow-living animals that impact their social lives.

“For example, individuals that are slow-lived might have more cautious personalities and explore less, changing their patterns of social interactions,” Silk says. “But there may also be an element that forming these relationships change how individuals reproduce and affect fast-lived and slow-lived species in different ways — this is something we raise as a possibility hoping it encourages further research.”

The researchers say more research is necessary to explore the connection between social relationships and the pace of life of animal species. But they have the tools they need to help make investigations happen.

“We are at a stage now where we are just beginning to learn lots about the patterns of social interactions of lots of species — tracking technology means we can model fine-scale behaviors like these with loggers that track individuals through space or record who is nearby,” Silk says. “We are hoping this now makes it possible to compare across species to see whether slow-lived species do indeed have these differentiated social relationships (or ‘friends and enemies’).” 

Answering these questions about social relationships can also help with other research.

“For example, as we know well from the past year, patterns of social interactions impact the spread of infectious disease through populations,” Silk says. “Therefore understanding how these social networks are related to the different life-histories of species can help us understand which might be more vulnerable to new diseases or which might have the right type of population structure to host diseases that spread to other species.”