Quote:
Originally Posted by Lanfear
What Seamus and Rosa wrote is absolutely correct but I always wondered whether we do experience evolution on our eyes due to 'technology'
In the past having bad eyesight would have meant that you can't hunt/work productively = can't provide for a family/feed yourself = don't produce offspring = genes for bad eyes are an evolutionary disadvantage
We had glasses since the middle ages and they were more readily available since a few hundered years now so having bad eyes no longer prevents you from having a job and therefore kids. Wouldn't that mean that the bad eyes genes are now more likely to be passed on?
I know that seeing more people with glasses in modern times is obviously a function of more testing & cheap access to glasses, but some of my friends are seriously blind without them and I can't imagine them functioning in a medieval society let alone as a hunter/gatherer.
Thoughts?
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Seems sensible enough. The point I was trying to make is that *maybe* the reason you see so much bad eye sight nowadays isn't because we are inheriting bad eye genes (tho presumably this must happen a bit for the reasons you outline), but simply because we are staring at screens (and books) all the time and its fucking our eyes up (the same way running fucks up your knees):
let me try this one more time. If you are near-sighted, you have a hard time focusing on things that are far away (your focal range is only things very near to you). Near-sightedness is far more common than far-sightedness. in order to focus on near things, you must bend your lens (the disk inside your eyeball... it physically changes shape to help you bring things into and out of focus.. i.e it bends).
My hypothesis was that the increased prevalence of near-sightedness arose because we now spend so much time focusing on near things (our screens and books) and as a result our lenses get stuck in that bent position and have a hard time unbending. in cave-man days they didn't have iproducts or books, and they probably spent a lot more time dynamically adjusting their focus to both look at near things (like each other) and to look at far things (like predators and big-game on the horizon). the difference would be frequency of bending and unbending... keeping it flexible, like a tight little underage gymnast. If this is all the case, then cave-men probably had better vison on average, not so much because they were genetically selecting for it, but rather because of how they used their eyes.
but this is all wild speculation. maybe there are genes for bad vision. must be a bit of that. maybe im totally full of shit. probably.