Underneath those horned helmets, Vikings may have sported big brains. Like other residents of the dark north, however, the Scandinavian pillagers would've needed the grandiose noggins to see, not to sack cities. Scientists have long known that polar days tend to be shorter and dimmer, on average, than their equatorial counterparts. Northern and southern peoples seem to compensate much like owls do, scientists report online today in the Proceedings of the Royal Society B. The researchers examined 55 skulls dating back to the 1800s and taken from various parts of the world. They discovered that humans living along the tropics tend to have smaller eye sockets than people dwelling at higher and lower latitudes . Since bigger eyes absorb more light, large polar orbs could make up for the twilight conditions there. In fact, high- and low-latitude natives seem to see just as well in low light as tropical people do in bright light, according to the study. Cerebral size seems to grow by a few milliliters with increasing and decreasing latitude, probably because the brain's visual centers expand as peepers widen.
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