To ensure better survival, mongooses have offspring at the same time: within a colony, pregnant females are usually born at the same time in a single night. This makes it impossible for the animals to identify which is their young animal.

The result: all mothers care for all boys, as researchers from the British universities of Exeter and Roehampton do in the journal » Nature Communications « to report. This gives rise to a “veil of ignorance” of a fair society, write experts. Mongoose are a group of mammals, the most famous of which are meerkats and mongooses.

In their study, researchers fed extra food to half of pregnant women in wild groups in Uganda. As a result, their young animals had a significantly higher birth weight. But then their mothers took especially good care of the less well-nourished offspring of other females, so that the weight would soon be adjusted.

“Most of the time, parents like their boys,” said Harry Marshall of the University of Roehampton. In the case of mongooses, however, the mothers do not know which of them are young animals. So they cannot take special care of them. “Our study shows that this ignorance leads to a fair distribution of resources — and ultimately a fair society,” Marshall said.