Chimpanzees may throw tantrums like toddlers, but their total brain size suggests they have more self-control than, say, a gerbil or fox squirrel, according to a new study of 36 species of mammals and birds ranging from orangutans to zebra finches.
Scientists at Duke University, UC 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 behavior. They 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, according to the study published today (April 21) in the journal of the Proceedings of the National Academy of Sciences. “The study levels the playing field on the question of animal intelligence,” said UC Berkeley psychologist Lucia Jacobs, a co-author of this study and of its precursor, a 2012 paper in the journal, Animal Cognition.
This latest study was led by evolutionary anthropologists Evan MacLean, Brian Hare and Charles Nunn of Duke University. The findings challenge prevailing assumptions that “relative” brain size is a more accurate predictor of intelligence than “absolute” brain size. One possibility, they posited, is that “as brains get larger, the total number of neurons increases and brains tend to become more modularized, perhaps facilitating the evolution of new cognitive networks.”