myopia a product of comfortable beds?

[nuffle]

Cecil reported that myopia appears to be a “product of civilization,” (http://www.straightdope.com/classics/a920724.html) in that “civilized” societies have a higher myopia rate than past and “uncivilized” societies. However, Cecil reports that the specific agent of civilization that causes this is unknown. This, then, gives me all the justificaiton I need to throw out my own wacky theory. Please pardon the unquoted use of “civilized” and “uncivilized” in the remaining post.

Uncivilized societies will tend not to have very soft fluffy beds. Therefore, members of those socieites sleep on their backs to minimize discomfort. Civilized beds are soft and fluffy, so people often will sleep on their sides. When sleeping on one’s side, the eyeballs undergo slight compression due to gravity and the pressure of the pillow. Through years of sleeping like this, eyes undergo slight shape changes, causing myopia (or possibly other sight problems).

Of course, lots of civilized people still sleep on their backs, but maybe they’re the ones that still have good eyes.

I liked this theory too much not to share it, even if it’s most likely completely wrong.

[Leaper]

Interesting theory, but I’m not exactly sure of the physical possibilities of it. Sure, the gravity thing could make a difference, but don’t the eyes feel its effects even when you’re standing upright? How exactly would there be a difference between standing, sleeping on one’s back, and sleeping on one’s side? Where would the pressure difference come from? And would the skull that surrounds one’s eyes allow for the “pressure of the pillow” to affect the shape of the eye?

I’m inclined to think not, but my knowledge of anatomy is limited. Does anyone know?

[Spiff]

Before corrective lenses were invented, myopic people died off before they could reproduce:

First, they were eaten by saber tooth tigers and trampled by wooly mammoths, then they died from being run over by chariots as they tried to cross the street to get to the vomitorium, then they died when they got lost in the woods and started to play with the cute little bear cubs that they mistook for rescue dogs.

So, the invention of corrective lenses is the element of “civilization” that has caused the increase in myopia. The people with the genes that cause the dimensions of their eyes to be too long (so an image comes into focus in front of the retina, i.e., myopia) can live long enough to pass those genes on to their offspring.

[Tigers2B1]

There seems to be a correlation of myopia with IQ and brain and eye size.

With respect to the high correlation between intelligence and myopia both within and between populations, Miller asserts that an obvious explanation is that high intelligence leads to more reading, and this leads to greater myopia. Yet, with respect to why myopia is so frequent among very intelligent people, he proposes ‘a pleitropic genetic effect by which one gene promotes the growth of both the brain and the eyeball, with the eyeball growth leading to myopia, or a [greater] predisposition to myopia.’ However, in the study Miller cites, where Myopia was twice as common among the extremely precocious students than among their siblings (whose IQs averaged 115), the non-gifted sib tended to spend about the same amount of time reading (Benbow 1986).

http://psycprints.ecs.soton.ac.uk/archive/00000144/

And evidence that myopia is inherited

A new study strongly indicates that the primary cause of nearsightedness is heredity. The study also suggests that the amount of time a child spends studying or reading plays a minor role in the development of myopia, or nearsightedness.

http://researchnews.osu.edu/archive/myokid.htm

[High_Cheese]

@Spiff

Before corrective lenses were invented, myopic people died off before they could reproduce:

First, they were eaten by saber tooth tigers and trampled by wooly mammoths, then they died from being run over by chariots as they tried to cross the street to get to the vomitorium, then they died when they got lost in the woods and started to play with the cute little bear cubs that they mistook for rescue dogs.

So, the invention of corrective lenses is the element of “civilization” that has caused the increase in myopia. The people with the genes that cause the dimensions of their eyes to be too long (so an image comes into focus in front of the retina, i.e., myopia) can live long enough to pass those genes on to their offspring.

Ah yes, he he. But the very funny, anecdotal theory you describe herewith does not “increase” the incidence of myopia, merely the incidence of discovery.
Neat-O! P.S.-----I hope I’m not too “out-of-date” with this response.

[Hostile_Dialect]

IANAD, but I have to go with Spiff’s explanation. Interesting theories, though.

FWIW, I’ve been wearing glasses/contacts for nearsightedness since fourth grade, and until last year (eleventh grade) I always slept on my back. (Now I sleep on my side, as it’s better for keeping your physiological alignment ‘in line’, sorry if that was redundant, I’m tired.)

[Xiphos]

@Spiff

Before corrective lenses were invented, myopic people died off before they could reproduce:

First, they were eaten by saber tooth tigers and trampled by wooly mammoths, then they died from being run over by chariots as they tried to cross the street to get to the vomitorium, then they died when they got lost in the woods and started to play with the cute little bear cubs that they mistook for rescue dogs.

So, the invention of corrective lenses is the element of “civilization” that has caused the increase in myopia. The people with the genes that cause the dimensions of their eyes to be too long (so an image comes into focus in front of the retina, i.e., myopia) can live long enough to pass those genes on to their offspring.

Sorry, doesn’t explain the stats the Perfect Master gave out: “The incidence of myopia in those age 56 and up was zero percent; in parents age 30 and up, 8 percent; in their children, 59 percent.” If the genes had been removed or reduced by selection it wouldn’t have recurred within a generation to such a high degree.