Brain size matters. Research has shown that social animals tend to have the largest brains, and that larger brains are correlated with greater self-control and emotional intelligence. But studies have also shown that wild animals tend to have larger brains that their domesticated counterparts, which raises an important question: are we making animals stupider by raising them to live by our sides?
According to NPR's Robert Krulwich, assuming that domesticated animals are "stupider" may not be accurate -- or fair. "Brain size doesn't always correlate with intelligence," Krulwich writes for Radiolab. "On some tests, laboratory rats outperformed wild rats, and domestic guinea pigs did better than wild cavies. But," he concedes, "most of the time ... when the test is about puzzle solving, wild animals win."
The reduction in brain size correlated with domestication doesn't happen immediately; individual animals aren't going to experience any mind shrinkage just by virtue of living with humans. But these changes that do occur over time have important implications for the characteristics of new species or breeds: domesticated animals are likely selected for limited aggression and increased friendliness, which might be the result of their smaller brains. That, in turn, raises yet another question: is a smaller brain really such a bad thing?