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.
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.