Animals with bigger brains show more self control

Researchers have linked self-control in animals to their brain size.

Scientists at Duke University, UC Berkeley, Stanford, Yale and more than two-dozen other research institutions found that the species with the largest brain volume - not volume relative to body size - showed superior cognitive powers in a series of food-foraging experiments.

Moreover, animals with the most varied diets showed the most self-restraint.

This latest study was led by evolutionary anthropologists Evan MacLean, Brian Hare and Charles Nunn of Duke University. Data was provided on bonobos, chimpanzees, gorillas, olive baboons, stump-tailed macaques, golden snub-nosed monkeys, brown, red-bellied and aye-aye lemurs, coyotes, dogs, gray wolves, Asian elephants, domestic pigeons, orange-winged amazons, Eurasian jays, western scrub jay, zebra finches and swamp sparrows.

In one experiment, creatures large and small were tested to see if they would advance toward a clear cylinder visibly containing food - showing a lack of self-restraint - after they had been trained to access the food through a side opening in an opaque cylinder. Large-brained primates such as gorillas quickly navigated their way to the treat or "bait." Smaller-brained animals did so with mixed results.

Jacobs and UC Berkeley doctoral student Mikel Delgado contributed the only rodent data in the study, putting some of the campus's fox squirrels and some Mongolian gerbils in their lab through food-foraging tasks.

The study has been published in the journal of the Proceedings of the National Academy of Sciences.