Grey Matters: Scientists Link Brain Size and Smarts

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.

So, Benson-Amram and her colleagues put a group of animals to the test, finding that species with relatively large brains for their bodies were the most successful at completing a problem-solving task, they reported on Jan. 25 in the journal Proceedings of the National Academy of Sciences.

"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

Benson-Amram and her team presented 140 zoo-dwelling mammalian carnivores, from 39 different species, with a puzzle box with a treat inside. To get to the tasty snack, the animal had to open an L-shaped latch on the box.

Designing a box that the animals couldn't just tear through with their maws was tricky, Benson-Amram said, because some of the animals have powerful jaws. Hyenas, for example, can bite through the femur of a giraffe. Ultimately, the researchers built a heavy, metal box with slats so the animals could see and smell what was inside.

source : livescience.com