The study of 36 species of mammals and birds 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.
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Also, animals with the most varied diets showed the most self-restraint, researchers said.
Scientists at Duke University, University of California Berkeley, Stanford, Yale and more than two-dozen other research institutions collaborated on this first large-scale investigation into the evolution of self-control, defined in the study as the ability to inhibit powerful but ultimately counter-productive behaviour.
The findings challenge prevailing assumptions that 'relative' brain size is a more accurate predictor of intelligence than 'absolute' brain size.
One possibility, researchers said, is that "as brains get larger, the total number of neurons increases and brains tend to become more modularised, perhaps facilitating the evolution of new cognitive networks."
While participating researchers all performed the same series of experiments, they did so on their own turf and on their own animal subjects.
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, researchers found.
The study was published in the journal of the Proceedings of the National Academy of Sciences.