Lemurs that spend much of their time in large tribes are more likely to steal food behind a human's back rather than in front of their faces . This behavior suggests that primates living in larger social groups tend to develop "social intelligence", according to a study published in the journal Plos One .
Evan L. MacLean and his colleagues at Duke University (USA) decided to analyze whether living in large networks is directly related to higher social skills . In an experiment carried out with sixty individuals of six different species of lemurs, they observed that, if pieces of food were placed on various plates and a human spectator in the room, the animals that belonged to large social groups, such as the Lemur catta , they observed where the human looked before choosing what food they should appropriate, to try not to be seen. And therefore they preferred the plate before which the person sat on his back. In contrast, lemurs of species that form small groups, such as the Eulemur mongoz , were indifferent to the posture and gaze of humans.
The work is the first to test the relationship between group size and social intelligence in multiple species. The results support the "social intelligence hypothesis," which suggests that life in large groups drove the evolution of social cognition in primates, including humans, said researcher Evan MacLean.
