Sunday, September 21, 2014
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A Skeptical View of Myopia as Sign of Evolutionary Degradation

Scientists often say nearsighted people would have been quickly weeded out of the population back in the stone age. Are they right? And if so, how have the four-eyed managed to proliferate so fast?

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:

Are children with myopia more intelligent? A literature review.

Czepita D, Lodygowska E, Czepita M.

Source

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

Abstract

PURPOSE:

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.

MATERIAL AND METHODS:

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

RESULTS:

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)".

CONCLUSIONS:

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.

 

About this blog
Faye Flam - writer
In pursuit of her stories, writer Faye Flam has weathered storms in Greenland, gotten frost nip at the South Pole, and floated weightless aboard NASA’s zero-g plane. She has a degree in geophysics from the California Institute of Technology and started her writing career with the Economist. She later took on the particle physics and cosmology beat at Science Magazine before coming to the Inquirer in 1995. Her previous science column, “Carnal Knowledge,” ran from 2005 to 2008. Her new column and blog, Planet of the Apes, explores the topic of evolution and runs here and in the Inquirer’s health section each Monday. Email Faye at fflam@phillynews.com. Reach Planet of the at fflam@phillynews.com.

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