• A spotted hyena investigates a puzzle box after an experimental trial that showed carnivore species with larger brains relative to their body size are better at solving problems. Image by Sarah Benson-Amram (Supplied)Source: Supplied
New evidence suggests that some mammals with larger brains are better at problem solving
Sandrine Ceurstemont

New Scientist
27 Jan 2016 - 9:45 PM  UPDATED 15 Feb 2016 - 5:04 PM

It’s a no-brainer: animals with bigger brains are better problem-solvers. But there has been little evidence for the idea – until now.

Sarah Benson-Amram at the University of Wyoming in Laramie and colleagues have tested it using puzzle boxes baited with food. When they presented these to 140 carnivores from 39 species in North American zoos, they found that those with larger brains relative to body mass, such as river otters and bears, were better at opening the boxes (see video).

“Meerkats and mongooses pretty much failed completely,” says Benson-Amram.

Problem-solving is linked to cognitive ability, she says, although intelligence is so broad that “it would be difficult, if not impossible, to measure”.

Another issue is whether the size of specific brain regions, for example the hippocampus, which deals with spatial memory tasks, is more important in problem-solving than overall brain size.

Benson-Amram and her team tackled this by creating virtual models of the carnivores’ brains. This allowed them to deduce the size of specific areas and examine the role they played.

The team concluded that overall relative brain size was still the best predictor of problem-solving ability. They also found that manual dexterity, or whether an animal lived in groups, was not a factor.

This contradicts the social brain hypothesis – the idea that complexities of group living are responsible for the evolution of large brains and cognitive ability.

No death blow

The results are not conclusive, says Evan MacLean from Duke University in Durham, North Carolina, who studies the evolution of animal brains.

“It’s far from a death blow for the social intelligence hypothesis,” he says, although he thinks the study is an impressive and rare effort to test problem-solving in a large number of species.

“Group living may be more associated with skill for solving social problems, and not necessarily related to solving physical problems, which is what was tested here,” MacLean says.

In addition, since the tests investigated the abilities of carnivores in zoos, they don’t necessarily indicate how their counterparts in the wild would perform. For example, a previous comparative study with hyenas showed that captive animals were far better problem-solvers.

“Captive work is great for seeing what a species is capable of, but looking at wild animals shows how important it is in their natural habitat,” says Benson-Amram.

She now wants to extend the work.

Journal reference: PNAS, DOI: 10.1073/pnas.1505913113

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