Social mammals live longer – but there is a price
Photo Credit: Leon Pauleikhoff
Scientific Frontline: Extended "At a Glance" Summary: Social Mammals and Longevity
The Core Concept: Mammal species that live in pairs or social groups consistently outlive solitary species, demonstrating that social organization naturally extends a species' maximum lifespan.
Key Distinction/Mechanism: While body size traditionally dictates animal lifespans, sociality acts as an independent factor that pulls a species' average lifespan upward. This occurs primarily through collective defense and the "dilution effect" against predators, which offsets the increased risk of infectious disease transmission found in larger groups.
Origin/History: Published in 2026 in the journal Ecology and Evolution, this concept was solidified by analyzing a massive dataset of 1,436 mammal species. The research was led by population biologists from the University of Southern Denmark alongside researchers from the University of Edinburgh.
Major Frameworks/Components:
- Life-History Trait Analysis: The cross-referencing of extensive databases detailing maximum lifespan, body mass, and social structures across the mammalian class.
- The Dilution Effect: An ecological principle where the statistical probability of an individual being preyed upon decreases as the size of their social group increases.
- Evolutionary Physiology: The theoretical framework explaining how long-term social living alters a species' physical evolution, naturally shifting biological energy allocation toward cellular maintenance and disease resistance.
Branch of Science: Population Biology, Evolutionary Biology, Ecology.
Future Application: These findings will inform ongoing medical and psychological research into the physiological health benefits of social networking in humans. Furthermore, it guides advanced behavioral tracking in wildlife monitoring, such as mapping individual social bonds in the St. Kilda Soay Sheep Project.
Why It Matters: This research reframes the scientific understanding of aging. It proves that longevity is not exclusively a cellular or genetic process, but a physiological trait deeply shaped by a species' social behavior and long-term evolutionary adaptations.
Living together may be the key to a longer life. A new study based on the largest dataset of its kind shows that mammals—from sheep to humans—that live in pairs or groups tend to live longer than solitary mammal species.
Using data from 1,436 mammal species, researchers found that species living in pairs or groups consistently outlive solitary species, even after accounting for body size and evolutionary history.
The researchers behind the study, published in Ecology and Evolution, combined large databases of life-history traits, using records of maximum lifespan for each species alongside information on body mass and social organization.
Species were broadly grouped as solitary, pair-living, or group-living. Pair-living species include animals in which a male and a female share a territory over multiple breeding seasons, while group-living species range from herds of zebras or elephants to complex primate societies.
Little Difference Between Pairs and Groups
The lead author of the study is population biologist and Associate Professor Owen R. Jones from the Department of Biology. The coauthors are Kevin Healy from the University of Edinburgh and Julia A. Jones, who was at the University of Southern Denmark when the research was conducted.
Across mammals, both pair-living and group-living species live longer than solitary ones. However, there is little difference between species living in pairs and those living in larger groups.
According to Jones, social organization should be seen as an added layer on top of well-known patterns, such as body size.
Bigger Animals Live Longer
“Bigger animals live longer than small ones,” he says, “but being social seems to pull species upward from the average lifespan expected for their body size.”
Bigger animals live longer because they generally face fewer predators, allowing them to allocate more resources to maintenance and repair, thereby extending their lifespans.
The study’s findings point to a balance of benefits and costs associated with living with others. One major advantage is protection against predation.
In a Group, You Help Each Other
“The big advantage is defense against predation,” Jones says. “Animals in groups benefit from increased vigilance. If you watch deer in a field, there is almost always at least one individual with its head up, scanning for danger. There is also the dilution effect, in which the chance of being caught decreases as group size increases.”
This does not mean that herd animals, such as zebras, live longer than their solitary predators, such as leopards. It means that a zebra would most probably have a shorter life expectancy if it were not a social animal.
Larger groups come with a downside, though: chief among these is a higher risk of infectious diseases spreading among individuals—a cost that may limit further gains in lifespan as group size increases.
Being Social Has an Impact on Human Health
“In humans, we know that networking, connections, and being social are linked to our health. I would not be surprised if this also applies to animals,” comments Jones, adding that individuals in mammalian groups (and other animals) often have certain relations or connections within the group hierarchy.
To investigate the concept of sociality in mammals further, he plans to study a population of sheep on the Scottish island of St. Kilda.
The St. Kilda Soay Sheep Project is a research initiative that monitors a population of wild sheep, and it has done so for nearly 40 years. The flock is surveyed approximately 30 times a year.
Can Sheep Have Friends?
“I will be looking for very simple signs of connection between individual sheep. If two sheep are often seen close to each other, it could be a sign that they have a connection. I cannot ask a sheep if it has a friend, but I can look at the surveys and see if it has a tendency to be physically closer to a particular other one.”
By investigating how social behavior is linked to the lifespans of sheep, humans, and other animals, we also gain an understanding of how behavior, physiology, and evolution are deeply intertwined, the researchers point out.
“We often think of aging as pure biology at the cellular level,” Jones says. “But behavior and social life matter too. Over evolutionary time, living together changes how species allocate energy to maintenance, disease resistance, and reproduction—and those changes become built into their physiology.”
Meet the Researcher
Owen R. Jones is a population biologist and an associate professor in the Population Biology Group at the Department of Biology and SDU Climate Cluster. His research focuses on understanding the drivers and consequences of the variety of life histories. Supporters of his research include the Danish Ministry of Higher Education and Science and the Novo Nordisk Foundation.
Title: Social Organisation Predicts Lifespan in Mammals
Authors: Owen R. Jones, Kevin Healy, and Julia A. Jones
Source/Credit: University of Southern Denmark | Birgitte Svennevig
Edited by: Scientific Frontline
Reference Number: ebio052126_01
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