Research has demonstrated that across many groups of animals, species with bigger brains often have better cognitive abilities, but it's been unclear whether overall brain size or the size of specific brain areas is the key.
New findings by neurobiologists at the University of Washington suggest that both patterns are important. The researchers found that bigger-bodied social wasps had larger brains and devoted up to three times more of their brain tissue to regions that coordinate social interactions, learning, memory and other complex behaviors.
Within a species, queens had larger central processing areas - the brain regions that manage complex behaviors - than did worker wasps.
"As the brain gets larger, there's disproportionately greater investment in the size of brain tissue for higher-order cognitive abilities," said Sean O'Donnell, lead author and UW psychology professor. "As larger wasp brains evolve, natural selection favors investing most heavily in the brain regions involved in learning and memory."
For smaller-brained species, cognitive power may be limited by their inability to invest in central brain regions. "In many kinds of animals, it's only with a larger brain - which is determined by body size - that more complex and flexible behaviors are achieved," O'Donnell said.
The results appear in the April 11 online edition of the Proceedings of the National Academy of Sciences