Sparrows have fewer friends as they age, just like people

Sparrows experience a dwindling social circle as they grow older, just as most humans do. It appears that sparrow friends tend to drift apart over time. But why does this happen?

A dedicated team of researchers has sought to decipher this intriguing phenomenon through a fascinating study that lends fresh insights into the social dynamics – not only of birds – but of aging individuals across species.

Changes in sociability with age

Older adults may reduce their social interaction due to being selective or because there are fewer companions of the same age. Here’s the puzzling question though, are these same factors at play in the avian world?

To investigate, researchers from Imperial College London set out to study an isolated population of sparrows on Lundy Island in the Bristol Channel.

Unlike humans, with complicated, multifaceted social lives, the bird population offers a simpler way to unravel the reasons behind the changes in sociability that come with age.

Social lives of sparrows

The researchers studied the social networks of the sparrows on the island. The findings revealed that like humans, older sparrows showed a reduced number of friends.

The reason for this could be the lack of evolutionary pressure to maintain sociability. While friendliness helps younger birds survive and breed more successfully, the same isn’t true for older birds.

“This evolutionary mechanism may also be at work in humans – it could be that older people are less inclined to new friends as they age,” said lead researcher Dr. Julia Schroeder, an expert in the Department of Life Sciences at Imperial.

“Combined with fewer same-age potential friends available, this could be a factor in the loneliness crisis among older people.”

Aging and evolution

Dr. Schroeder suggests that this evolutionary mechanism might operate similarly in humans, leading to fewer social interactions as they age.

Combined with the decreasing number of potential friends of the same age, this factor heavily contributes to the increasing loneliness among the elderly.

“Our study is one of the first to suggest that birds, like mammals, also reduce the size of their social network as they age. Specifically, the number of friendships, and how central a bird is to the wider social network, declined with age,” said study co-author Dr. Jamie Dunning, now at the University of Leeds.

Sparrows and their friends

Lundy Island is home to a closed population of sparrows, meaning that no individual arrives or leaves the island.

This unique characteristic enabled the research team to collect comprehensive and accurate data on the local sparrow population, including their ages, breeding success, and social networks.

Social lives of aging sparrows

Previous research by the team had shown that a good social network proved beneficial to sparrows in successfully breeding.

However, the current research focuses on whether friendliness continues to be advantageous at the other end of the life span. It seems that with age, not being friendly doesn’t have a cost.

“’Friendliness’, at least for sparrows, may change with age. When they’re young, it helps them to make friends, giving them an evolutionary ‘benefit,'” noted Dr. Schroeder.

“But once they’ve reproduced, it seems like being unfriendly has no evolutionary ‘cost’ – there are no downsides that mean those genes wouldn’t be passed on.”

The findings from this study might help us understand similar age-related conditions in humans.

“Ultimately, the study of friendliness with age – whether it be in sparrows or humans – may help us understand how to help older people make new friends, and reduce the burden of loneliness,” noted Dr. Schroeder.

Broader implications of the research

The insights derived from studying the sparrows on Lundy Island extend beyond avian social dynamics, offering broader implications for conservation efforts.

Understanding the natural social structures and how they change with age can inform conservationists about the needs of older individuals in small, isolated populations.

This knowledge is vital in making decisions about habitat management and the social environments necessary to support diverse age groups in conservation programs.

Considering age-specific social requirements may improve efforts to maintain biodiversity and ensure the well-being of aging wildlife in their natural habitats.

Future research directions

The study on Lundy Island paves the way for future research to explore additional factors influencing social behavior in aging populations.

One promising avenue is to examine the role of environmental variables, such as changes in food availability or climate conditions, that might shape these social patterns.

Additionally, extending similar studies to different species and ecosystems could unveil further correlations and differences, enriching our understanding of the evolutionary and ecological dimensions of aging across the animal kingdom.

Ultimately, the study brings us a step closer to understanding the mechanisms at play in the evolution of social behavior with age.

The study is published in the journal Philosophical Transactions of the Royal Society B Biological Sciences.

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