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.
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.
'Fantastically smart' insects
On a smaller scale, scientists are finally moving past the idea that locusts, ants, bees and other insects are simple machines that respond to events in predictable ways, says Dr Sarah Farris, an evolutionary neurobiologist at West Virginia University in Morgantown.
Study after study now shows that insects can, in fact, change their behaviour depending on the circumstances.
Honeybees, which have been the focus of Chittka's work, have tiny brains with fewer than a million neurones.
Yet, the insects can classify shapes as symmetrical or asymmetrical. They can pick objects based on concepts like "same" or "different."
They can also learn to stop flying after a prescribed number of landmarks rather than after a certain distance.
Ants and bees have notoriously complex social systems. Along with other insects, they can move in a surprising number of ways to communicate or get around.
Bees, for example, can sting, scout for food, guard the hive and fan their wings for ventilation, along with more than 50 other behaviours. "The insect's behavioural repertoire, in fact, surpasses that of some vertebrates."
"They are fantastically smart," says Chittka. "Perhaps we are only amazed by this because we think small brains shouldn't be able to do it."
In fact, scientists have calculated that a few hundred neurones should be enough to enable counting and a few thousand neurones could support consciousness.
Engineers hope to use that kind of information to design programs that do things like recognise faces from a variety of angles, distances and emotional states. That's something bees can do, but computers still can't.
"Knowing how an insect functions and produces complex behaviours with a brain that's a million-fold smaller than ours makes it a little easier to envision that we might be able to model some of these behaviours," says Farris.
"It's wonderful to see that insects are finally being compared equally with vertebrate animals," she says. "They have smaller brains, but they still have complex enough brains to do these things."