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This is one of many reasons the perfect eye argument by creationists is utter bullshit.
Ugh that drives me crazy. The human eye is a perfect example of observable evolution. Organisms exist with every stage of eye development, from a photosensitive spot to a more advanced convergent evolution of our eye. And the human eye is poorly designed for it’s current use, resulting in a significant percentage of people requiring corrective lenses.
It’s a good example of evolving towards a local maximum then being unable to travel through a valley to a more optimal design. As such it confirms exactly what evolutionary theory would predict, and not what “intelligent design by an omniscient creator” would predict.
As someone with chronic back pain, eyes are the least of my issues with creationists theories
exactly, bananas - amirite?
Relevant video: https://youtu.be/2X1iwLqM2t0
This arrangement actually optimizes color vision in the daytime and night vision at night. Evolution selected for the correct arrangement for those of us living on land:
https://theconversation.com/look-your-eyes-are-wired-backwards-heres-why-38319
This is just saying that the glial cells help make this less bad than it could be, no? Nothing about why neurons behind receptors would be worse
No, glia support neurons; they do things like redirecting blood flow to more-active-than-usual neurons, mylenate axons, etc. They wouldn’t form a mesh around neurons’ photoreceptors the same way they do neurons’ somas and axons. What the article describes is that glia actually are critical at allowing for color vision during the day and night vision at night, since on land we’d get too much blue light to see color with much fidelity were it not for glia, and a similar filtration process helps us see at night. It’s not that it’s not as bad as it could be, it’s actually that vision is better this way (barring one small blind spot outside of our fovea–which, being outside of the fovea, would have low acuity anyways).
Couldn’t a neurons-behind-eyes human just have fewer blue receptors? Or a brain that attenuates the blue signal?
Blue light is important for night vision, so either of those options would lead to less of an ability to see well after sunset.
More mindflayer propaganda.
✅ Discount number of limbs
✅ Cheaply made eyeballs
✅ Held together with a bunch of inflexible bones
Wait, am I just an off-band octopus?
Damn.
- just one brain
I am biology illiterate. Explanation please.
Cephalopod precursors evolved eyes and then brains developed from the eye so their eye is structured correctly.
Vertebrate precursors evolved the brian first and the eye evolved out the brain as a sensory stub. So it’s upside down and inside out like in picture.
The nerve cluster goes through the back of the eye splits and folds back to end in light receptors. Light hase to go through the nerves before hitting the sensor.
There is even a reflective layer after the sensors that gives the sensors a second chance at picking up the light. This is what causes the red eye or green eye you sometimes see in flash photography.
It would require a genetic rebuild to fix this and the intermediate steps evolution usually use would be so disadvantageous they are selected against. So the right combo of mutations to give us a working octopus eye is VERY unlikely to happen.
Hypothetically, if we managed to make a genetically modified human with the eye that you are talking about, what advantages/disadvantages would it have over our current eyes?
No blind spot and probably better light sensitivity. But it’s not like we really need higher light sensitivity as land-dwellers.
better light sensitivity
I like to think of it as “colors and light so brilliant and pretty it’s like tripping shrooms”
It says vertebrae wouldn’t that include cats who have insanely utilitarian eyes
It does, but their eyes still have blind spots and their eyes could possibly be even better if their photoreceptors were oriented towards the incoming light.
Hypothetically, what would be the advantages of “correcting” this evolutionary mistake in humans?
Bragging rights
No blind spot and better light detection. The light having to pass through the nerves causes a lot to be lost.
Octopuses don’t have a dead spot in the eyes I guess
Scallops, oysters, mussels and clams have anywhere between 40 and 200 eyes. https://en.wikipedia.org/wiki/Mollusc_eye
Shit just evolves. It doesn’t evolve correctly or incorrectly.
Evolution likes local maxima. Getting out of them is difficult. That’s what the OOP meant with “evolution was powerless to correct it”.
Getting out of local maxima means you first have to go with a worse setup until you get to a new, better local maxima. That’s why evolution doesn’t really do that all that often and instead prefers small optimizations.
(I use “like” and “prefer” not to say that evolution has goals or emotions, but to say that that’s what the “algorithm” of evolution leads to.)
https://en.wikipedia.org/wiki/Cephalopod_eye
(At a glance, this article needs some touching up and hasn’t been meaningfully contributed to in some years.)
Lol, at first glance I thought this was a poster for some new movie. All we need to do is change the font of “Cephalopods” to something exciting, and arrange the listed species as if they were actors’ names.
I’ve said it for years, as soon as it’s commercially available I’m getting photoreceptors realignment surgery.
Quick way to find your blindspot:
-
Close your right eye
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Hold your phone/monitor 1ft (30cm) away from your face
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Look at the ‘x’ below with your left eye
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Slowly bring your phone towards you (or your face towards the monitor) until the ‘.’ disappears
. x
Well
It doesnt
God I love Splatoon character design
The
.is not visible to me at any distance without taking my eyes off thex
-
Do I understand correctly that our ancestors had left the water before this upgrade dropped for fish?
Is this something we could like, fix?
Uhhhh gonna say we could theoretically, but I imagine the brain has evolved a bunch of other subfuntions to make this work.
Though I bet you’d adjust super fast if it were only a visual change since our brains are great at adapting
Geordi eyes.
Predator vision… Which I think is the same thing
If vertebrae don’t have it, it means they don’t need it.
that’s not how evolution works. Evolution is not able to produce global maxima, only local maxima.
Not really. Needs is a fairly strict word. If it was needed they would not survive without. Useful, i agree with you
Need requires context. “if they don’t have it, they don’t need it to survive”. And survival is conditioned upon the environment. If something emerges that exploited the blindspot, then we’d need it to survive.
What was the evolutionary pressure that caused receptor orientation to be different in cephalopods that vertebral animals didn’t encounter? Or did they encounter it and have other adaptations that allowed it to deal with them.
Dont they eventually produce global maxima by iterating towards it through the many degrees of freedom allowed by crazy mutations and time?
There needs to be pressure for animals with a mutation to reproduce more or animals without the mutation to die before reproduction. Like a disease for example. Otherwise the genes don’t spread and just disappear in the soup of all that species genes and never become dominant. Without any evolutionary pressure the mutation will only spread in one family and probably be gone after a few generations. Like there are human families that are more likely to produce offspring with 6 digits on their hands, but since it isn’t more advantageous than 5 digits (6 digit people don’t produce more offspring and 5 digit people aren’t more likely to die before reaching reproductive maturity) that mutation doesn’t spread across the entire species. Sure if you could sample the genome of every human on earth and identify every advantageous gene mutation you could build the ultimate human DNA. But that’s artificially created, something like that will never happen through evolutionary pathways.
Imagine an alligator. Quite good at catching prey with their current anatomy.
An alligator that shoots laser beams for tracking and bullets would be even better. There’s however no path from their current anatomy to this state, regardless of the randomness and timescale for mutations. In fact, in order to achieve this higher state several non advantageous intermediates would be necessary and therefore never selected for.
So no, evolution can’t achieve global maxima, it can however optimize the shit out of what it’s given to work with.
The problem is that the landscape of where the global maxima are changes faster than evolution can keep up. If the environment were entirely static, then yes, mathematically speaking any random optimizer would eventually reach a global maximum. However, it could take, say, 1050 years or more to jump from a local maximum to a distant, higher maximum.
Ah good point, thanks
No, you are 100% wrong.
no they’re not. by definition if you don’t have what you need you don’t survive. we definitively don’t need it. or at least haven’t for millions of years. that’s different from saying we wouldn’t benefit from it.
although that’s not a guarantee either. more information isn’t always better.
Okay true, but I still feel the comment was misleading. If it were phrased as “If vertebrae don’t have it, it means it wouldn’t improve their fitness” it would be wrong. I’ll admit that the comment as worded is true, but it does depend on a very literal interpretation of what “needs” means. Why even post that? In my opinion, that makes it low-quality content, so worth a downvote.
disagree. again, we don’t even know if such a change would be beneficial.
also, more importantly, the post is entirely stupid.
suboptimal by what measure? became disadvantageous how? against what? last time i checked ve**rtebrates were still dominating. now even more than they did during the ages of dinosaurs.
evolution was too late to correct it… what? first of all, is it even a mistake to correct? where’s the evidence of that? second of all, did evolution stop? too late how? it’s complete bullshit, and if anything the original comment wasn’t harsh enough on it.
I’m not claiming that this change in how eyes work would be an improvement. I’m claiming that the following does not hold generally: “Doesn’t have adaptation X ⇒ adaptation X would not improve fitness.”
yeah but that’s not part of the original comment, not even by implication. the opposite is also not true so it doesn’t factor in at all. even though you’re not claiming it would be an improvement the original post clearly does and that’s what the top level comment is countering.
Yes, but the top level comment is countering it using an incorrect application of the theory of evolution. If top-level-comment really meant “needs,” then it would not be a counter to the original post. If by “needs” they meant more colloquially “would be an improvement,” then it may counter the original comment, but it’s not actually a valid argument.
