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Mongooses Evolved A Fair Society Because Parents Don’t Know Which Pups Are Theirs

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Stephen Luntz

Freelance Writer

clockJun 28 2021, 13:03 UTC
mongoose and pup

Banded mongooses don't know which pups are their own, so they give each young member of the group the care it needs, creating equality at the point where they leave the den. Image Credit: Milan Vachal/Shutterstock.com

Certain human problems are common among other social animals. The banded mongoose has come up with some never-seen-before solutions. New research reveals mongooses have evolved a unique way of reducing the risk that some members of the pack start life unfairly disadvantaged. The way they have done it couldn’t be directly applied to humans, but that doesn't mean it is without implications.

Banded mongooses (or mongeese if you'd prefer) have developed an unusual pattern where an average of five members of a group give birth on the same night, known as birth synchrony. This probably originated to make it easier for males to guard the whole litter at once, while the new mothers go out to feed, and preventing adults from killing others' pups. However, it has had the intriguing consequence that mothers don’t exclusively suckle their own young, instead caring for pups communally. 

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“Birth synchrony has led to the unusual situation that mothers don’t know which pups are their own, and therefore cannot choose to give them extra care,” explained Dr Harry Marshall of the University of Roehampton in a statement. "Our study shows that this ignorance leads to a fairer allocation of resources – in effect, a fairer society."

As reported in Nature Communications, Marshall and the University of Exeter’s Professor Michael Cant conducted an experiment on seven groups of mongooses, feeding half the pregnant females in each group 50 grams of cooked egg to supplement the invertebrates they caught themselves. The other half were left to their own devices. 

Predictably, the better-fed mothers gave birth to heavier pups. In most species this advantage would ripple through life, increasing prospects for greater survival and more offspring to the beneficiaries of the experimenter’s lottery. Cant and Marshall expected something different among the mongeese. 

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"We predicted that a 'veil of ignorance' would cause females to focus their care on the pups most in need – and this is what we found,” Cant said. "Those most able to help offer it to the most needy, and in doing so minimize the risk that their own offspring will face a disadvantage.” By the time the pups left the den those with control mothers weighed as much as those who were fed extra; the extra care from the better-fed mothers ensured the initially smaller pups caught up.

Philosophers use John Rawls’ “Veil of Ignorance” to try to design the ideal society. If people don’t know whether they will end up rich and powerful or poor and weak, they usually prefer a more even distribution of wealth. This seldom persuades those who know they’re the ones that will benefit from large inheritances to take the same position. 

Humans don’t practice birth synchrony, and would be able to identify our own offspring if we did, at least with DNA testing. However, inheritance taxes used to meet the health and educational needs of the most disadvantaged children would have a similar effect. Perhaps, as with mongooses, this would improve overall welfare.

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While the epitome of fairness within their groups, banded mongooses also engage in vicious inter-gropup warfare. Sometimes these fights are even initiated as dating opportunities to prevent inbreeding, making Tinder look quite tame by comparison.  


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