Scientists have been long puzzled over why women can show just as much intelligence as men, although their brains are 8pc smaller.
Now a study by universities in Los Angeles and Madrid has shown that for women, brain size does not matter because they are more efficient.
The research has implications for assumptions made about a person's intelligence.
The study, published in the journal Intelligence, carried out a series of intelligence tests on men and women.
Despite the fact the women had smaller brains, they performed better in inductive reasoning, some numerical skills and were better at keeping track of a changing situation – although men did better on spatial intelligence.
The researchers concluded that women's brains are able to complete and even excel at complicated tasks with less energy and fewer neurons.
"At this structural level, females might show greater efficiency requiring less neural material for achieving behavioural results on a par with males," the paper read. In contrast, a larger hippocampus in men, can mean better performance in intelligence tests.
Trevor Robbins, professor of Cognitive Neuroscience at Cambridge University, said the results show size does not matter – for women.
"The smaller size could represent more intense packing of nerve cells or more active signalling between them," he said. "Meaning they are operating more efficiently."
"The research suggests that, in women, the smaller the hippocampus, the better it works."