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On 07.02.2023 at 08:00
Modified on 07.02.2023 at 8:00 p.m.
Researchers have discovered a link between life expectancy and social bonding in hundreds of animals. A hereditary faculty, 31 sociability genes have been identified in certain species.
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It’s confirmed: unity is strength. Mammals that live in groups have a longer lifespan than solitary animals, according to a study by Chinese and Australian researchers. To reach this conclusion, they looked at the characteristics of nearly 1,000 species in light of two main factors, their lifespan and their social organization. The animals studied were thus divided into three categories: those which organize themselves into herds or packs, those which form couples and those which live alone. Scientists then found that an elephant surrounded by its congeners greatly increases its longevity compared to a solitary red squirrel.
Life expectancy varies enormously among the thousand animals observed. From two years for a shrew to almost 200 years for a humpback whale. You might think it’s a matter of size, but with two short years to live, the shrew that survives on its own is a far cry from the horseshoe bat that weighs exactly the same but can live up to 30 years.
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Solitary animals more exposed to predators and hunger
So how to explain that some animals have developed solitary habits. According to the researchers, it’s a matter of genes. By pushing their analyzes, they identified 31 in relation to the herd instinct and community life, a hereditary faculty therefore. In their study, they argue: “group living reduces the mortality rate because it limits the risk of predation and facilitates access to food. The more the social bonds are stable and strong, the more the longevity of the animals progresses”. They add that “these benefits outweigh the disadvantages of life in society such as competition for reproduction or the stress caused by the highest hierarchical positions”.
Previous research had already established this link between sociability and life expectancy. Among baboons, which live in groups, it has also been observed that the most integrated individuals have a higher survival rate than those who are on the margins, despite being part of the same clan.
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A theory that may be too simplistic
The conclusions of the Sino-Australian study do not convince everyone. Asked by the British newspaper The Guardian, the doctor in evolutionary biology Celine Frere tempers from her University of Queensland: “They claim that animals that live in groups have a higher life expectancy than others. But it depends on many other factors, starting with their environment. We must also take into account their mode of reproduction.
According to her, the smallest animals, whether they live alone or not, have a higher rate of reproduction than larger animals. She specifies: “in the logic of evolution, every animal aims to transmit its genes to the future generation. An animal that lives two years will ultimately have an offspring equivalent to that of an animal that lives 200 years.
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