Grey Matters: Scientists Link Brain Size and Smarts
Animals in the bear family were among the best problem-solvers in a new study detailed Jan. 25, 2016, in PNAS.
Credit: AndreAnita/

Having a big head might not be such a bad thing, if it means you have a gigantic brain. Animals with bigger brains may be better problem-solvers, according to a new study.

Scientists long thought a correlation existed between an animal's relative brain size and its cognitive abilities, but even after decades of research, controversy over the answer abounds. In addition, little experimental data exists on the topic, said Sarah Benson-Amram, of the University of Wyoming in Laramie.


"There's always been this assumption that if you have a big brain, you're smart. We know that brains are costly energetically, so the species that devote more of their resources to their brain must be doing it for a reason. And that reason has always been assumed to be intelligence," said Benson-Amram, the study's lead author. [The 5 Smartest Non-Primates on the Planet]

However, that doesn't always mean bigger beasts are the intellectuals of the animal kingdom. Though bigger brains tend to follow body size — a sperm whale's brain weighs in at 20 pounds (9 kilograms), compared with a desert ant's 0.00028-gram brain — that's not always the case. Some species, such as dolphins, have larger brains than expected for their body size, while others, such as the hippo and blue whale, have much smaller brains relative to their body sizes.

Beastly problem-solvers



In a test of animal smarts, a spotted hyena had to open a latch to get at a hunk of meat inside a cage.
Credit: Sarah Benson-Amram



"River otters are amazing to watch," Benson-Amram said. "They are very active. They would use their noses to flip the box repeatedly over and over again."] Ultimately, some of the otters opened the latch.

The badger, for its part, seemed to think the food was beneath the box and dug an enormous hole, hoping to get at the snack that way.


Sociality and intelligence



In this study, the researchers didn't find any link between an animal's sociality and its success with the problem-solving task.

"That's not to say that the social brain hypothesis is invalidated," Benson-Amram said. "But in this particular study, we didn't find support for it."

The researchers also looked for a correlation between an animal's manual dexterity and its success. They found that an animal's skill with its forepaws didn't seem to help them as much as relative brain size in opening the box. 




Instead of assuming "brains make you smart, that's why we have them," she said, "our study is a great step forward in providing some concrete experimental data that yes, in fact, having a relatively larger brain does increase your ability to solve a novel problem."
