# OK, explain human myopia to me
**URL:** https://boards.straightdope.com/t/ok-explain-human-myopia-to-me/452990
**Category:** Factual Questions
**Created:** [June 15, 2008, 8:17am UTC](https://boards.straightdope.com/t/ok-explain-human-myopia-to-me/452990 "2008-06-15T08:17:20Z")
**Posts on this page:** 18
**Page:** 1
### Author:  [@GameHat](https://boards.straightdope.com/u/GameHat)
#### Post date: [June 15, 2008, 8:17am UTC](https://boards.straightdope.com/t/ok-explain-human-myopia-to-me/452990/1 "2008-06-15T08:17:20Z")
Humans have been around for what, 130,000 years now?
What’s always puzzled me:
My vision is terrible. Something like 20/225. Without my glasses, all I can see is colors and fuzzy shapes. I can barely get around my own apartment without banging into things.
And yet I am the product of thousands of years of human evolution.
Have humans always had such terrible vision? I just don’t see how a pre-civilization human could possibly function in the wild with vision as terrible as mine.
I’ve heard a few theories on how focusing on text at close ranges causes the eyeball to narrow, bringing on myopia - but I’ve not yet seen a good study that definitively establishes this.
Anyone know a bit more than I do?
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### Author:  [@Broomstick](https://boards.straightdope.com/u/Broomstick)
#### Post date: [June 15, 2008, 11:40am UTC](https://boards.straightdope.com/t/ok-explain-human-myopia-to-me/452990/2 "2008-06-15T11:40:49Z")
[QUOTE=GameHat]
And yet I am the product of thousands of years of human evolution.
[/quote]
Actually, millions of years of homid evolution.
> [@](#):
>
> Have humans always had such terrible vision? I just don’t see how a pre-civilization human could possibly function in the wild with vision as terrible as mine.
Some have - the thing is, in the wilds during the stone age such myopic humans probably got eaten by sabertooth tigers and the like more often than those with normal sight. With result would be a lot of healthy adults with good vision, good teeth, correct number of limbs, etc. because the defectives would have been eliminated fairly early in life.
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### Author:  [@Si\_Amigo](https://boards.straightdope.com/u/Si_Amigo)
#### Post date: [June 15, 2008, 11:49am UTC](https://boards.straightdope.com/t/ok-explain-human-myopia-to-me/452990/3 "2008-06-15T11:49:12Z")
Consider this, while male hunter’s were most likely killed off while young, the females who didn’t particiapte in hunts could pass on the bad eyesight. You only had to live to thirteen or so in order to pass it on to the next genaration.
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### Author:  [@Alive\_At\_Both\_Ends](https://boards.straightdope.com/u/Alive_At_Both_Ends)
#### Post date: [June 15, 2008, 12:19pm UTC](https://boards.straightdope.com/t/ok-explain-human-myopia-to-me/452990/4 "2008-06-15T12:19:28Z")
Is it definitely established that myopia is inherited? Because if it isn’t, it won’t be subject to evolution. I’ve heard a theory that many cases of myopia (not all) are the result of children sleeping with the light on - the idea is that the human eye needs regular periods of darkness in infancy to develop properly. Naturally, this would not apply in the days before artificial light.
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### Author:  [@Squink](https://boards.straightdope.com/u/Squink)
#### Post date: [June 15, 2008, 1:08pm UTC](https://boards.straightdope.com/t/ok-explain-human-myopia-to-me/452990/5 "2008-06-15T13:08:21Z")
[QUOTE=Broomstick]
the thing is, in the wilds during the stone age such myopic humans probably got eaten by sabertooth tigers and the like more often than those with normal sight.
[/QUOTE]
You don’t need to be able to see a sabertooth’s nose hairs to know that you’d better get your spear up. Those with 20/200 vision might step on a few more scorpions than the perfectly sighted, but anything that subtends a greater angle than the letter E at 20 feet can still be dealt with. Modern life, with its high speeds and detailed signage everywhere, leads us to overestmate the importance of seeing distant objects clearly.
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### Author:  [@Sleel](https://boards.straightdope.com/u/Sleel)
#### Post date: [June 15, 2008, 1:16pm UTC](https://boards.straightdope.com/t/ok-explain-human-myopia-to-me/452990/6 "2008-06-15T13:16:50Z")
Arguably, modern living [is to blame](http://www.straightdope.com/classics/a5_105.html) for at least some myopia. It’s possible that your eyesight either wouldn’t be as bad, or would be normal if you’d lived in a culture where you didn’t have to use your eyes to focus for long periods of time at close objects.
(Although, Cecil’s crack about indoor plumbing is a little off considering that the ancient Greeks had hot and cold water systems figured out already.)
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### Author:  [@kimera](https://boards.straightdope.com/u/kimera)
#### Post date: [June 15, 2008, 8:37pm UTC](https://boards.straightdope.com/t/ok-explain-human-myopia-to-me/452990/7 "2008-06-15T20:37:52Z")
As **Sleel** noted, modern living is to blame. There have been other examples of cultures that became modernized and the children who were raised on books and television were far more myopic than their older relatives. The predilection for myopia seems to be inheritable. I read many books as a child but have excellent eyesight while I have friends who read less and watched the same amount of TV as I who are myopic.
> [@](#):
>
> Consider this, while male hunter’s were most likely killed off while young, the females who didn’t particiapte in hunts could pass on the bad eyesight. You only had to live to thirteen or so in order to pass it on to the next genaration.
You had to live considerably beyond 13. For one, most Hunter-gatherer women didn’t reach menarche until their late teens/early 20s, after that, you had to raise the child (breast feed and such) until the child was capable of surviving on its own. Considering a mortality rate of about 50% (or more), our race would’ve never survived if myopia was as common in the past as it is now.
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### Author:  [@Jeff\_Lichtman](https://boards.straightdope.com/u/Jeff_Lichtman)
#### Post date: [June 16, 2008, 10:01pm UTC](https://boards.straightdope.com/t/ok-explain-human-myopia-to-me/452990/8 "2008-06-16T22:01:53Z")
Assuming myopia is genetic, it’s possible that the associated genetic condition is also linked to a trait with positive survival value. That is, it could be like the sickle-cell gene, which gives partial immunity to malaria to someone with one copy of the gene, and sickle-cell anemia to someone with two copies of the gene.
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### Author:  [@Nava](https://boards.straightdope.com/u/Nava)
#### Post date: [June 17, 2008, 1:25pm UTC](https://boards.straightdope.com/t/ok-explain-human-myopia-to-me/452990/9 "2008-06-17T13:25:15Z")
Well, there’s myopia and myopia, too…
Some 55 years ago, my grandmother told Mom “not the one with the glasses!” Well, gee, the myopic girl married the guy with astigmatism and ta-dah, three myopic kids (I also had astigmatism, then I got laserized). But the worst all four of us have/had is less than 3 diopters: while I don’t know how to translate this into the terms used by Americans, the cutout limit for military service in Spain used to be “more than 4 diopters in each eye or 6 in one”, anybody with better eyesight than that was supposed to be able to handle a rifle and aim it in more-or-less the general intended direction.
Someone could be unable to hit a rabbit with a bowshot and still be able to set up snares, you know. So long as he caught the rabbit, there would be rabbit for dinner!
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### Author:  [@KneadToKnow](https://boards.straightdope.com/u/KneadToKnow)
#### Post date: [June 17, 2008, 1:43pm UTC](https://boards.straightdope.com/t/ok-explain-human-myopia-to-me/452990/10 "2008-06-17T13:43:58Z")
[QUOTE=Squink]
You don’t need to be able to see a sabertooth’s nose hairs to know that you’d better get your spear up.
[/QUOTE]
Words to live by.
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### Author:  [@Toxylon](https://boards.straightdope.com/u/Toxylon)
#### Post date: [June 17, 2008, 5:09pm UTC](https://boards.straightdope.com/t/ok-explain-human-myopia-to-me/452990/11 "2008-06-17T17:09:47Z")
Some studies have been conducted on the subject of hunter-gatherer myopia.
> **[Elsevier Journal Catalog: Browse Peer-Reviewed Journals List](https://www.elsevier.com/products/journals)**
>
> Browse through a wide range of high-quality academic journals offered by Elsevier, including open access options, to enrich your research journey.
The classic text is Young, F., Baldwin, W., Leary, G. and D. West. 1969. The Transmission of Refractive Errors within Eskimo Families. The American journal of optometry and archives of American Academy of Optometry 46: 676-685.
From what I recall (can’t access the paper online), among the older Eskimo individuals in the study myopia was very rare, while in the younger populace near-sightedness skyrocketed. Modern schooling and the transition from a traditional diet of lipid- and micronutrient-rich seafood to white flour and sugar have been pointed as a possible reason for the rapid change in Eskimo eyesight.
Then there’s this: [History of The Paleo Diet - The Paleo Diet®](http://www.thepaleodiet.com/published_research/)
Number 19:
> [@](#):
>
> Cordain L, Eaton SB, Brand Miller J, Lindeberg S, Jensen C. An evolutionary analysis of the etiology and pathogenesis of juvenile-onset myopia. Acta Ophthalmologica Scandinavica, 2002; 80:125-135.
>
> ABSTRACT
>
> The available evidence suggests that both genes and environment play a crucial role in the development of juvenile-onset myopia. When the human visual system is examined from an evolutionary perspective, it becomes apparent that humans, living in the original environmental niche for which our species is genetically adapted (as hunter-gatherers), are either slightly hypermetropic or emmetropic and rarely develop myopia. Myopia occurs when novel environmental conditions associated with modern civilization are introduced into the hunter-gatherer lifestyle. The excessive near work of reading is most frequently cited as the main environmental stressor underlying the development of myopia. In this review we point out how a previously unrecognized diet-related malady (chronic hyperinsulinaemia) may play a key role in the pathogenesis of juvenile-onset myopia because of its interaction with hormonal regulation of vitreal chamber growth.
FWIW, early European travelers (as well as many later ethnographers) seem to have consistently marvelled at the keen eyesight of members of various African, American, Asian and Australian hunter-gatherer groups. My own experience as a myopic primitive archer-hunter, gatherer and occasional trapper tells me bad eyesight must’ve been a very serious issue to any sub-neolithic person, male or female. Placing traps as well as locating edible plants efficiently, as well as simple orienteering in the wild woods requires a sharp vision beyond the first couple of feet.
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### Author:  [@j666](https://boards.straightdope.com/u/j666)
#### Post date: [June 18, 2008, 4:49am UTC](https://boards.straightdope.com/t/ok-explain-human-myopia-to-me/452990/12 "2008-06-18T04:49:30Z")
The model of evolution we were all taught in school assumes a single gene trait, full dominance, and individual survival.
If many genes effect the phenotype (eyeball shape), the ‘negative’ gene is recessive (the ‘good eye’ gene is dominant or partially dominant), OR the individual has other attributes which contribute highly to the survival of the group (is very good at chipping spear heads), the ‘bad eye-sight’ gene will be passed on.
So, your forebears were very talented (or maybe just very attractive) and got lots of opportunities to breed.
Remember, _species_ evolve.
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### Author:  [@Bootis](https://boards.straightdope.com/u/Bootis)
#### Post date: [June 18, 2008, 7:47am UTC](https://boards.straightdope.com/t/ok-explain-human-myopia-to-me/452990/13 "2008-06-18T07:47:31Z")
I would have to guess poor vision would be less a hindrance for one who never wore glasses, since they would have adjusted to it much more than someone of equally poor vision who is used to having it corrected.
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### Author:  [@Broomstick](https://boards.straightdope.com/u/Broomstick)
#### Post date: [June 18, 2008, 10:31am UTC](https://boards.straightdope.com/t/ok-explain-human-myopia-to-me/452990/14 "2008-06-18T10:31:21Z")
I wish to note that myopia is one of the few vision defects that can _improve_ with age, with the onset of presbyopia. Granted, this would not improve someone 20/200 to 20/20, but it would tend to improve _minor_ myopic defects, possibly skewing results when comparing older members of a community to younger ones.
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### Author:  [@kimera](https://boards.straightdope.com/u/kimera)
#### Post date: [June 18, 2008, 4:03pm UTC](https://boards.straightdope.com/t/ok-explain-human-myopia-to-me/452990/15 "2008-06-18T16:03:48Z")
[QUOTE=j666]
The model of evolution we were all taught in school assumes a single gene trait, full dominance, and individual survival.
[/QUOTE]
Well, this is incorrect. There are many factors that affect the outward expression of genes. And, if it were entirely genetic and not caused by modern factors, you wouldn’t see the sudden burst of myopia in the younger generation of societies that have been ‘modernized.’ Remember, environment contributes heavily to the outward expression of our genes. We aren’t just programmed robots who will develop the same no matter what environment we or our ancestors grew up in.
And **Jeff Lichtman** , there is no evidence that that is the case with myopia. However, I’ve seen quite a few researchers arguing that is the case for **schizophrenia**.
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### Author:  [@j666](https://boards.straightdope.com/u/j666)
#### Post date: [June 19, 2008, 2:06am UTC](https://boards.straightdope.com/t/ok-explain-human-myopia-to-me/452990/16 "2008-06-19T02:06:22Z")
[Quote= j666]
The model of evolution we were all taught in school assumes a single gene trait, full dominance, and individual survival.
[/QUOTE]
[QUOTE=kimera]
Well, this is incorrect. There are many factors that affect the outward expression of genes.
[/QUOTE]
Well, I’m glad that science education has improved over the years, but my statement is true for a great many people.
As for your second statement, I did not say anything that would contradict that; I was just focusing my comment on the **genetic** assumptions in the OP. I know many who don’t entirely grasp that phenotype is not entirely dependent on genotype.
I think there is too much research yet to be done on evaluating the contributions of phenotype and environmental factors on phenotype to unequivocally assert that myopia is due to environmental factors. Remember that sudden increases in diagnoses often correlate to technological improvements in the means to detect conditions.
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### Author:  [@kimera](https://boards.straightdope.com/u/kimera)
#### Post date: [June 19, 2008, 3:37am UTC](https://boards.straightdope.com/t/ok-explain-human-myopia-to-me/452990/17 "2008-06-19T03:37:42Z")
[QUOTE=j666]
Remember that sudden increases in diagnoses often correlate to technological improvements in the means to detect conditions.
[/QUOTE]
If this were the case, why the difference in generations within the same geographic environment and among the same population? If technological improvements in detection were the the major contributing factor, then we would find similar rates of myopia in the older generations as the younger ones.
And of course, as I stated earlier, environment alone is not enough to cause myopia. Otherwise I, who read many books as a child, would’ve been nearsighted.
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### Author:  [@j666](https://boards.straightdope.com/u/j666)
#### Post date: [June 19, 2008, 3:44am UTC](https://boards.straightdope.com/t/ok-explain-human-myopia-to-me/452990/18 "2008-06-19T03:44:13Z")
[QUOTE=kimera]
If this were the case, why the difference in generations within the same geographic environment and among the same population? If technological improvements in detection were the the major contributing factor, then we would find similar rates of myopia in the older generations as the younger ones.
And of course, as I stated earlier, environment alone is not enough to cause myopia. Otherwise I, who read many books as a child, would’ve been nearsighted.
[/QUOTE]
Correlation does not imply causation.
No population is static.
Near-sighted-ness does have a negative survival impact for the individual, but not so great a one as to eliminate the trait.