Not ‘Bird Brained:' Study Shows Birds Have More Brains Than Monkeys

Birds may be known to have small brains, but some are just as smart as monkeys, scientists said.

Researchers found that the macaw has more neurons in its forebrain, which is the part of the brain associated with intelligent behavior, compared to the macaque monkey.

"For a long time having a 'bird brain' was considered to be a bad thing: Now it turns out that it should be a compliment," Suzana Herculano-Houzel, neuroscientist at Vanderbilt University in Prague and senior author of the study, said in a statement published in Science Daily.

In the first study, the researchers measured the number of neurons in the brains of more than two dozen species of birds, ranging from as small as the zebra finch to the six-foot-tall emu, and determined how birds are able to perform complicated cognitive tasks.

In previous studies where cognitive abilities of parrots and crows were compared with primates, scientists have found that birds could manufacture and use tools, solve problems, make inferences about cause-effect, recognize their reflections from the mirror and plan for future needs.

It was found that neurons in the brains of parrots and crows are of a much higher density than in primate brains and that the proportion of neurons in the forebrain is significantly higher.

"We found that birds, especially songbirds and parrots, have surprisingly large numbers of neurons in their pallium: the part of the brain that corresponds to the cerebral cortex, which supports higher cognition functions such as planning for the future or finding patterns. That explains why they exhibit levels of cognition at least as complex as primates," said Herculano-Houzel.

The size of avian brains could be the reason as they are much smaller and densely packed, the researchers found.

The researchers said that although the relationship between neuron count and intelligence has not yet been established, avian brains could provide birds with much higher "cognitive power" than mammals.

Another important implication of the study is that it demonstrates that there is more than one way to build a larger brain.

In previous studies, scientists thought that as brains grow bigger, neurons also grow in size as they are connected over long distances.

But avian brain studies show that to add neurons in the brain, most neurons can be kept small and locally connected and allow only a small part to grow large enough to make the longer connections, researchers said.

The study was published in the Proceedings of the National Academy of Sciences.