In this thread, some posters argue that, by process of evolution, fish lose their ability to see because mutations that decrease the sight-function don’t affect survivability.
If this is the case, does that mean that mutations in the human genetic pool that:
[ul]
[li]increase our susceptibility to eye diseases/defects[/li][li]generally weaken our vision[/li][li]increase the rate of “aging” of the eye[/li][li]create new vulnerabilities in the eye[/li][li]etc[/li][/ul]
…could possibly become the norm for newborns?
I ask this because it seems like we’ve had some remarkable innovations in opthalmology in the past hundred or so years, and it would seem that the better we get at it, the less our genetic eye-strength has to do with it. People can survive now with perfect vision who were nearly blind by the age of 12.
Is the future human child destined to have corrective lenses of some kind? Or corrective eye surgery?
It’s very possible…however, it won’t happen for many thousands of generations, perhaps even millions of generations. It takes a very long time for traits to evolve, and we’re a whopping 200 years into real advances in optometry. Maybe in 38000 AD they’ll all need glasses.
I don’t mean to be snarky about it but many people who were nearly blind by the age of 12 seem to have survived long enough to reproduce. Since the development of social structures and civilization blind people are not doomed to die prematurely for lack of ability to forage on their own. So those traits are not necessarily culled out of the gene pool to begin with.
That’s true, but simply surviving as a minority of the population doesn’t strike me as having a large effect on the overall population.
These days, it seems like everyone wears glasses/contact lenses. Maybe I’m operating under the false assumption that human beings generally had good sight-functions before advances in social welfare and ophthalmology.
P.S. Thanks for the spelling heads-up. For some reason, my spell-checker believes “opthalmology” is a word.
This is no different from any other once debilitating condition that we now live with. Except for a few very deadly childhood genetic disorders, very few people fail to reproduce because of their genetic makeup. Except for possessors of the “ugly” or “nerdy” gene. Perhaps in AD 1 million, we’ll all be dumb and beautiful.
Unless the genes also lead to some increased reproductive success, it would be very unusual for it become all-pervasive. It’s certainly possible due to genetic drift if the traits are really benign, but you also have to think about how rapidly the human population is increasing, and whether such genetic drift could occur under those conditions.
Please consider that in the bad old days you didn’t need perfect vision, you just needed vision that was good enough. Particularly in societies that didn’t read or write, being slightly farsighted likely wasn’t an issue.
Nowadays, we correct everyone to an arbitrary standard.
Yeah, that’s something I always like to bring up in these types of threads. Evolution of the sorts described in the OP operates on the time scale of tens of the thousands of years (in a large, geographically diverse population like our species). What will our genetic engineering technology look like 500 years in the future? We can only guess.
The intelligence that we use for medical advances is, itself, part of our ongoing evolution. And our ability to correct (or even prevent) our deficiencies is evolving much faster than the deficiencies themselves.
I had a friend who did research on this very subject in college or grad school. He told me that there has been a measurable worsening of human vision since the advent of glasses. Sorry, no cite.
But that ability seems to be based on cultural/technological “evolution”, not biological evolution.
Be careful. You need to define what you mean by “human vision”. Do you mean the average visual capacity of the entire human population, or the peak visual capacity of any given individual? I suspect that latter might be getting better, just because there as so many more of us, and so much opportunity for variation.