Why Do So Many People Need Glasses?

It has become a rarity in our modern world, to find someone who doesn't need contacts or glasses. It blows my mind that it's almost assumed that everyone has a pair of one or the other. However, way back when, when early versions of homo sapiens wandered about, they didn't have access to corrective lenses. Did people in early civilizations just put up with terrible eye sight? Or did something happen over the course of our evolutionary history that led to a majority of the population needing contacts or glasses?

There are several theories as of to why this is the case, but the most common one is that people have always had some members of the population that had a hard time seeing. Before we had glasses, these people would die before being able to reproduce, and were selected against from an evolutionary stand point. So for a while, most people had decent eye sight. Eventually, however, this genetic "defect" was accommodated with corrective lenses, and people with poor eyesight were able to reproduce, pass their genes along, and now we have a bunch of people who can't see anything. And instead of dying, they make babies and pass their bad eyesight genes along.

JT Surge

Bibliography:

http://everything2.com/title/Why+do+so+many+people+wear+glasses%253F