Altruism In Animals

How red squirrels exemplify the evolution of altruism

 

Once considered, in those memorable words of Tennyson, “red in tooth and claw,” the supposedly ruthless natural world is proving far more altruistic than ever thought possible. In the most recent example of animal compassion, a study published earlier this month by Nature Communications shows that orphaned baby squirrels are sometimes adopted by other squirrel moms.

Researchers from the University of Alberta have been monitoring the red squirrel population in the Kulane National Park in northern Canada for more than 20 years, but it was only recently that the doctoral studentJamie Gorrell discovered a curious phenomenon. While making his regular checks on squirrel nests, Gorrell found one nest had an extra pup in it. At first, he assumed he had erred in his earlier count, but then he realized the extra pup was older than the rest of the litter. Furthermore, this pup’s eyes were still shut and its muscles undeveloped, meaning it couldn’t have simply wandered over by itself. So what happened?

It turns out the mother of the mysterious extra pup had been eaten by a predator - perhaps a hawk or an owl - and a neighbouring squirrel noticed the nest had fallen silent. This squirrel went over to investigate, found orphaned pups, and brought one back to her own nest to raise as her own. Going back through their records, the researchers determined there had been similar adoptions over the years and the key was that the two mothers were always related, perhaps sisters or cousins.

“Natural selection is about promoting your own genes, passing on your genetic lineage, so a female adopting a relative helps pass on her own genes, the genes she has in common with that juvenile,” Gorrell says.

This falls in line with the current theory on the evolution of altruism, known as Hamilton’s Rule, which states that an organism will sacrifice to help another organism so long as they share enough genetic material. This rule was made famous by Richard Dawkins, but despite the rather cynical title of his seminal work - The Selfish Gene - incidents such as these squirrel adoptions are also a reminder of something rather wonderful: whatever its root genetic cause, altruism is hard-wired into animals and compassion is a natural state.

And, of course, these squirrel adoptions shed no light at all on the marvel of interspecies adoptions such as this case of the lioness in Kenya who repeatedly adopts orphaned oryxes or the gaggle of cat-adopting-squirrel stories such as this that populate Internet video sites. With ‘selfish’ genes playing no role in these adoptions, Gorrell can only theorize they are the result of females who become overwhelmed and confused by their hormones. Or, one could choose a more optimistic interpretation: kindness and compassion are such powerful forces that they eclipse all genetic considerations.

Photo Credit: R. W. Taylor