High latitude people have bigger brains

London: People who live at higher latitudes have larger eyes and more processing power in their brains to deal with visual information, compared with those living nearer the equator, a study suggests.

"As you move away from the equator, there's less and less light available, so humans have had to evolve bigger and bigger eyes," said Eiluned Pearce from the Institute of Cognitive and Evolutionary Anthropology at Oxford University, a lead author on the study.

"Their brains also need to be bigger to deal with the extra visual input. Having bigger brains doesn't mean that higher-latitude humans are smarter, it just means they need bigger brains to be able to see well where they live."

This suggests that someone from Greenland and someone from Kenya will have the same ability to discern detail, but the person from the higher latitude needs more brainpower and bigger eyes to deal with the lower light levels.

Professor Robin Dunbar, director of the Institute of Cognitive and Evolutionary Anthropology at Oxford University and a co-author of the study, said that people whose ancestors have lived within the Arctic circle, have eyeballs 20 per cent bigger than people whose ancestors lived near the equator.

They have an associated increase in the size of the brain's visual cortex, which previous studies have shown correlates with the size of the eyeball.

Brain volume is known to increase with latitude: people living at high latitudes north and south of the equator have bigger brains than people living near the equator.

Dunbar said that scientists have wondered whether these inherited differences in total brain volume were driven by the pressure to adapt to low light levels at high latitudes.

The researchers measured the brain volumes and eye sockets of 55 skulls kept at the Oxford University Museum of Natural History dating from the 19th century. The skulls represented 12 different populations from around the world. The results, published yesterday in the journal Biology Letters, showed the biggest brains were from Scandinavia, while the smallest brains came from Micronesia.