Viewing a single comment thread. View all comments

69SadBoi69 t1_itlmd2a wrote

Reply to comment by Cavemanb0b in Is every single living cell adjacent to or “have access to” a capillary? Are there living cells not next to a blood/O2 source, and if so, how do they survive? by Friggin

I wonder why so many people these days have bad vision despite being able to reproduce? Is it something environmental that is recent enough to not be selected out of the population?

I had to get glasses in elementary school, and presumably most of our ancestors in that situation would not have survived long in the distant past without strong social support

1

kafkasquared t1_itlty0a wrote

it’s a good question. but having good vision to the extent that we need it today (to read whiteboards, computers, books, etc.) wasn’t necessary for the majority of human evolution. sure, you may be a bit less capable at seeing that buffalo off in the distance, but it needn’t be sharp for you to see it, and as long as whomever you’re with is seeing it, you can still assist with the kill. maybe people with truly horrible vision were selected out, but in general, i don’t see why you couldn’t thrive and reproduce in primitive times with, for instance, typical near-sightedness.

3

chronoflect t1_itmo59p wrote

If I recall correctly, we are currently going through a near-sightedness epidemic that is thought to be caused by things like not spending enough time outside in bright sunlight. Basically, our eyes need environmental cues to properly finish growing, and our modern lifestyles are stunting this growth and forcing more people to develop near-sightedness that would have otherwise had normal vision.

2