Near Arctic, Humans Evolved Big Brains

Visual cortex biggest in low-light areas


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People who live farthest from the equator appear to have evolved large eyes and brains to see better in low-light environments, according to new research from Oxford University. Larger eyes, which afford polar dwellers better vision in the dark, require bigger visual cortexes. Researchers at Oxford measured eye-socket size and brain volume in 55 skulls representing 12 populations, then plotted the measurements against the latitude of the skull’s country of origin. Brain volume does not reflect intelligence, but rather a larger visual processing area. The study also notes, however, that large eyes do not enhance vision in normal daylight, supporting the researchers’ claim that larger eyes and brains are needed to compensate in low-light conditions. The full study was published online Wednesday in the journal Biology Letters.

Read more at Oxford University Media