It’s dim up north, so people living at higher latitudes have bigger eyes and brains, research at Oxford University has found.

As early humans moved further north they evolved more developed visual processing to help them cope with long winters and grey skies.

Scientists measured the eye sockets and brain capacity of 55 human skulls representing 12 different populations worldwide.

They found that the further north of the equator people lived, the bigger their eyes and visual brain regions were.

Lead researcher Eiluned Pearce, from the university’s school of anthropology, said: “As you move away from the equator, there’s less and less light available, so humans have had to evolve bigger and bigger eyes.

“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.”

People’s actual ability to see in natural daylight is roughly the same wherever they live.