Brain power: 'size isn't everything'

When it comes to brain power, it's the complexity of neuronal connections, rather than the size of the brain itself, that is most important, say scientists.

Dr Lars Chittka of the Queen Mary University of London and Dr Jeremy Niven of the University of Cambridge lay out their arguments in the journal Current Biology.

According to a growing number of studies, some insects can count, categorise objects, even recognise human faces - all with brains the size of pinheads.

Despite many attempts to link the volume of an animal's brain with the depth of its intelligence, scientists now propose that it's the complexity of connections between brain cells that matters most.

Studying those connections - a more manageable task in a little brain than in a big one - could help researchers understand how bigger brains, including those of humans, work.
Bigger isn't necessarily better

Figuring out how a relatively small number of cells work together to process complex concepts could also lead to "smarter" computers that do some of the same tasks.

"The question is: If these insects can do these things with such little brains, what does anything need a big brain for?" says Chittka. "Bigger isn't necessarily better, and in some cases it could be quite the opposite."

Because we are intelligent animals with big brains, people have long assumed that big brains are smarter brains. Yet, scientists have found scant evidence to support that view, says Chittka.

Studies that have made those connections are fraught with problems. "If you try many measurements," he says, "Eventually you will find one that shows a correlation."

There's a lot of evidence, on the other hand, that overall size is irrelevant when it comes to brain power.

Among humans, individuals with larger noggins don't have higher IQs.

Whales, with brains that weigh up to 9 kilograms, are no smarter than people, with our measly 1.4-kilogram brains.

Instead of contributing intelligence, big brains might just help support bigger bodies, which have larger muscles to coordinate and more sensory information coming in.

Like computers, says Chittka, size might add storage capacity but necessarily speed or usefulness. At the same time, it takes a lot of energy to support a big brain.