Eye Size Is Determined by Distance From the Equator

Eye Size is not accidental. It is determined by evolutionary factors. This is not so obvious today because in the twentieth century people moved to new countries in regions quite different from their place of origin.

Eye sockets were measured from 55 skulls of native people throughout the world. The skulls were in museum collections from the 1800s. Large eyes were synonymous with large craniums. The native population of Micronesia had the smallest eyes. Scandinavians had the largest. This is contrary to the belief that Africans have the largest eyes.

Eyes size is affected by the length of day and sun brightness. Bigger craniums were due to more brain allocation to sight. It did not make people smarter.

This finding must mean that being able to get about in low light was important for survival. Features important for survival until the age of reproduction are carried on to later generations. Some things, however, can remain in a population if they affect life after puberty, for example sickle cell anemia.
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