科学美国人60秒:Big Social Group Makes Lemurs Cannier

Good news for big-time networking primates: other primates that live in large social groups have more street smarts than their comrades with smaller social circles. So finds a study in the journal PLoS ONE. [Evan L. MacLean et al., Group Size Predicts Social but Not Nonsocial Cognition in Lemurs] [Also see

Researchers tested the circumstances under which lemurs would pilfer food from people. The study included ring-tailed lemurs, which come from large social groups, as well as lemurs from small-groups, like the mongoose lemur. The lemurs all had the same brain size, so would be presumed to have similar raw intelligence. 

Humans sat in a room with either a plate of food on the table in front of them or behind them. A third group of people was blindfolded, with the plate in front of them. 

Lemurs from large social groups tended to steal the food if the person’s back was to it. Lemurs from smaller social groups went for the food as frequently regardless of its position. And no lemurs appeared to understand the purpose of a blindfold.

The researchers interpret the results as showing that social factors can influence a species’ smarts. So you could be outwitted by a birdbrain, if he has a lot of friends.

—Amy Kraft