Like humans, dolphins with life-long friendships age slower, study finds

Friendship could be ‘anti-ageing secret’ across all social animals, scientists say

Male bottlenose dolphins with strong friendships age more slowly compared to their more solitary peers, according to a new study that reveals the importance of social bonding for healthier ageing in mammals.

Bottlenose dolphins can form friendships that can last decades, similar to companionship seen in humans.

Previous research has shown that male dolphins of the species hang out, play together, surf waves for fun, rest side by side, and form long-lasting, deep social bonds.

This pattern of bonding is unique to males, as friendship in the female dolphins is known to be influenced by having offspring of similar age.

“It reminds me of two kindergarten buddies who stay together through school, careers, and retirement and share all of life’s joys and challenges,” explains wildlife biologist Livia Gerber from Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO).

In a new study, researchers analysed 50 skin tissue samples from 38 bottlenose dolphins in Shark Bay.

Scientists also assessed data on social connections between dolphins in the bay based on years' worth of observations.

They found that male dolphins with strong social bonds aged slowly compared to their peers who lived lonelier lives.

“We knew social bonds helped animals live longer, but this is the first time we have shown that they affect the ageing process,” said Gerber, lead author of the study published in Nature Communications Biology.

“Social connections are so important for health that they slow down ageing at the cellular level,” she said.

Lonelier dolphins may have to hunt for themselves, compete for mates without backup, and face sharks and other predators – factors that can contribute to a stressful existence, much like in humans, researchers say.

“Having friends means you hunt together, watch each other's backs, and share the load,” Dr Gerber said.

Male bottlenose dolphins (Simon Allen)

Until now, most research into the effects of friendships on ageing has focused on an chronological animal’s age since birth and lifespan.

However, in the latest study, scientists estimated the true biological age of the dolphins based on individual DNA markers.

Such an “epigenetic clock” provides a better indicator of an animal’s overall health and ageing status, studies have shown.

In previous studies, epigenetic clocks have unravelled how factors like pollution, depression, and positive or negative social bonds impact biological age.

“Increasingly, we are also using epigenetic data to advance our knowledge of the ecology of wild populations, including the epigenetic clocks used here,” said Lee Rollins, another author of the study from the University of New South Wales.

The findings highlight the importance of investing time in meaningful relationships, along with healthy eating and exercising for a longer life, scientists say.

“The health benefits of friendship are not unique to humans, but are a fundamental biological principle across social mammals,” Dr Gerber said.

“I am predicting that we will find that friendship is a natural anti-ageing secret across social animals,” she said.