Insects and Encephalization Quotient

The finding that big brains are not necessarily better comes as no surprise to Lars Chittka of Queen Mary, University of London, who studies bees. Bees' brains are only 1 cubic millimetre with a mere million neurons, yet bees can build complex nests, take care of their brood, defend their colony and reach consensus about where to build a new home. One study has even found that they can learn faster than vertebrates, including human infants (Animal Learning and Cognition by John M. Pearce, p 11). Instead of marvelling at the bees' abilities, however, the researchers discarded the test as a measure of intelligence. "There may be good reasons to be uncomfortable with equating learning speed with intelligence," says Chittka, "but that large-brained mammals don't top the chart shouldn't be one of them."

He believes scientists have often been dismissive of insect abilities simply because insects have small brains. No one would seriously suggest that a smaller computer was an inferior computer merely because of its size, he says, yet that still seems to happen with brains. He argues that it is time to get beyond size and numbers of neurons and start looking at neural circuitry. Cognitive abilities such as numerosity, attention and categorisation - all found in insects - seem to require only small numbers of neurons. So it may turn out that brain size has less to do with cognitive capacity and behavioural repertoire than we have assumed (Current Biology, DOI: 10.1016/j.cub.2009.08.023). "We've gone as far as we can with size," he says."

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