A Skeptical View of Myopia as Sign of Evolutionary Degradation

I've often heard scientists rather glibly point to nearsighted people as an example of human degradation. Now that we no longer have to hunt for our food, the thinking goes, natural selection is letting all kinds of defective examples of humanity survive and reproduce. Myopics are always singled out first.

I 'm biased, since I can't see the big E on the eye chart, but I can't help wondering if there's more to the story. One interesting thing about nearsightedness is that most of us aren't born that way. I saw quite well before I learned to read, but it was all downhill after that.

Today a kind reader sent me a discussion he was having with some science-oriented, nearsighted friends about a possible connection between myopia and high IQ. A paper written by a Polish team found such a correlation. I had never heard of this before, but it seems plausible that reading hundreds of books could have a positive effect on IQ and a deleterious effect on vision.  Apparently, however, the authors of this paper tried to correct for number of books read. Here's what they found:

Czepita D, Lodygowska E, Czepita M.

Katedra i Klinika Okulistyki Pomorskiej Akademii Medycznej w Szczecinie al. Powstańców Wlkp. 72, 70-111 Szczecin.

Refractive errors are a serious worldwide problem. So far a few papers have described the relationship between refractive errors and intelligence. However, based on the growing interest into the relationship between refractive errors and intelligence quotient (IQ) we decided to present and discuss the latest results of the clinical studies on that subject.

A review of the literature concerning the relationship between refractive errors and IQ was done.

In 1958 Nadell and Hirsch found that children in America with myopia have a higher IQ. A similar relationship has been described by other researchers from the USA, the Czech Republic, Denmark, Israel, New Zealand, and Singapore. In other related studies, it was reported that myopic children regardless of their IQ gain better school achievements--table 1. It was also observed that schoolchildren with hyperopia have a lower IQ and gain worse school achievements--table 2. Several hypotheses explaining the relationship between refractive errors and intelligence have been published. Recently, Saw et al. concluded that higher IQ may be associated with myopia, independent of books read per week, in schoolchildren. According to them "the association between genetically driven IQ and myopia of hereditary predisposition could be forged because of a pleiotropic relationship between IQ and myopia in which the same causal factor is reflected in both genetic traits. There may be similar genes affecting eye size or growth (associated with myopia) and neocortical size (possibly associated with IQ)".

The conducted clinical observations suggest that children with myopia may have a higher IQ. This relationship is most probably determined by genetic and environmental factors.

This will make a great topic to research for a column. The discussion among my readers also delved into the problems extremely myopic people often have with sports that involve a ball flying through the air, and the tendency to classify cross country running as a nerd sport. Apparently there's some data showing that among high school athletes, cross country runners have the highest GPAs.

I also wonder whether we know being nearsighted was so deadly for hunter-gatherers, since it's not clear everyone in a tribe had to hunt or gather. Anthropologists say our species was wearing clothes or ornamentation for tens of thousands of years, and in Europe, people needed good clothes for survival. And humans have been dividing labor as long as we've been human.  So even back in the hunter/gatherer days, someone who was good at sewing clothes might have been saved from having to hunt or gather. Without my glasses or contacts I can thread the tiniest needle in seconds. It would be interesting to know if there are nearsighted hunter-gatherers today, and if so, do they work as artists, perhaps, or clothing-makers.