11-04-2024

Social aging: What animals can teach us about getting older

Earth.com staff writer

A growing body of research suggests that, like humans, animals also adjust their social behaviors as they age.

A special issue of Philosophical Transactions of the Royal Society B recently published 16 studies exploring this topic, with six led by the University of Leeds.

The studies reveal how social patterns shift as animals grow older, providing insights into the potential biological and social benefits of these changes.

One of the studies focused on red deer on Scotland’s Isle of Rum, particularly on the behavior of older female deer, or does. As the deer age, they interact less with their peers. This reduction in socialization may help them avoid competition and reduce their risk of parasite infection.

Josh Firth from the University of Leeds, one of the editors of this special issue, highlighted that such behavior may be widespread across species, as it allows individuals to avoid health risks associated with social interactions.

“These kinds of effects might be expected across societies, where individuals might avoid social interactions as they become more vulnerable to the costs of infection,” Firth explained.

The shift in behavior among aging deer has parallels in human behavior, especially seen during the COVID-19 pandemic when many older adults limited their social activities to avoid exposure to illness.

“Wild animals provide a good model system for considering the costs and benefits of changing social behavior with age,” Firth added.

Another notable study investigated how aging impacts social behavior in house sparrows. Research led by Julia Schroeder at Imperial College London, with additional input from Jamie Dunning, found that older sparrows tend to shrink their social circles.

“Our study is one of the first to suggest that birds, like mammals, also reduce the size of their social network as they age,” Dunning said. This decline could be influenced by the deaths of peers and the challenges older birds face in forming new bonds.

The research on Lundy Island offered a unique setting, as the isolated population of sparrows has no birds entering or leaving, allowing scientists to monitor each bird’s social connections throughout its life.

According to Schroeder, understanding the dynamics of these aging friendships may shed light on how social patterns evolve among birds and even offer insights into similar behaviors in other species.

Broad applications across species

These studies go beyond mammals and birds, extending to insects, which may not immediately come to mind when considering social dynamics. Professor Amanda Bretman’s work with Drosophila fruit flies showed that social environments impact aging even in simpler animals.

“In humans, a poor social environment can have the same level of impact as smoking or obesity on healthy aging,” Bretman noted. Her team’s research found that social interactions can significantly affect lifespan and aging, even in insects.

Studying the impact of social behavior in fruit flies offers a controlled environment where researchers can observe the mechanics of social aging.

These insights could potentially apply to broader research on aging in humans, helping scientists better understand the underlying processes that link social behaviors and health outcomes across different life stages.

In their studies of fruit flies, Bretman’s team could precisely manipulate the flies’ social surroundings, gaining a deeper look into why animals, and perhaps humans, might adjust social behaviors with age.

The research underscores that the social environment can vary by gender, timing, and social structure. By looking at how even insects adapt their behavior based on social context, scientists hope to reveal fundamental patterns that apply across species, possibly suggesting strategies for promoting healthy social aging.

These findings offer potential insights for human social dynamics as well. Firth noted that animal models are valuable for understanding the roots of social aging in human societies, where shifts in social habits can affect physical and mental health outcomes.

“Animal systems are now widely considered as well placed for developing our fundamental understanding of aging societies,” he explained. Observing animal behavior may provide clues on supporting social connections and minimizing isolation in human populations as they age.

Looking forward, researchers intend to explore the intricacies of social aging further. Schroeder’s team plans to continue studying the life-long social patterns of house sparrows, examining how friendships form and evolve.

The researchers believe that such detailed studies could illuminate the complexity of aging not only in animals but also offer parallels to human aging, as people similarly adapt their social interactions to match their life stage and health needs.

In addition, Bretman’s team is keen to examine how social environments impact health across different life stages in simpler animals. Since insects are easier to study in controlled environments, they can serve as useful models to understand the biological mechanisms that drive social aging, possibly uncovering processes that can apply to more complex animals, including humans.

The breadth of these studies highlights that changing social behaviors with age is a general phenomenon across species. From deer reducing their social interactions to avoid health risks to sparrows experiencing a natural decline in friendships as peers pass on, the social effects of aging are universal.

The insights provided by this special issue reveal that the social consequences of aging are not unique to humans. Instead, they reflect a broader biological principle that has significant implications for understanding both animal and human health across the lifespan.

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