How did eyes evolve?

[lightbulb27]

Like... if life evolved from simple cells and bacteria and such... which can't see I assume, it just bumps around running into stuff... then how did stuff evolve to see things? And smell and hearing for that matter?

Here's a fun shark video from the ocean ramsey channel, enjoy... these sharks did a lot of evolving to have these eyes that see so well (and of cours their noses). no doubt... they see us...

Ask the universe...

We didn't evolve, it was made by aliens

This is how it worked...

I really don't know

[zeitgeist057]

An excerpt from "The Blind Watchmaker", by Richard Dawkins: (p.313 if you want to read more. Also some relevant subject matter on p. 81)

"Now, how do we account for the fact that just the right set of 1,000
steps were taken to result in the eye as we know it? Natural selection's
explanation is well known. Reducing it to its simplest form, at each
one of the 1,000 steps, mutation offered a number of alternatives, only
one of which was favoured because it aided survival. The 1,000 steps of
evolution represent 1,000 successive choice points, at each of which
most of the alternatives led to death. The adaptive complexity of the
modem eye is the end-product of 1,000 successful unconscious
'choices'. The species has followed a particular path through the
labyrinth of all possibilities. There were 1,000 branch-points along the
path, and at each one the survivors were the ones that happened to take
the turning that led to improved eyesight. The wayside is littered with
the dead bodies of the failures who took the wrong turning at each one
of the 1,000 successive choice points. The eye that we know is the
end-product of a sequence of 1,000 successful selective 'choices'."

A hypothetical scenario as an example: some simple organism is replicated with a mutation, in the form of a cell which has a simple receptor that reacts to light/shadow. When light/shadow changes, there is a reflex and that organism moves away from the change. If all the other organisms of the same species don't have this mutation, then they go about their business normally, regardless of changes in light/shadow. This mutation proves to be beneficial, as it promotes the organism's ability to maintain homeostasis (it uses fewer resources to maintain its health, such as staying out of sunlight and not drying up, not overheating, not requiring extra fluids). It is more successful, and replicates. Organisms that have this adaptation are more successful, and those without it eventually disappear. That was step one. The next step is another mutation, which is a further refinement of that simple receptor, so that it is slightly more complex. For example, it consists of two cells now, instead of just one. Two might evolve to three, and so on until there is a more advanced structure that starts to look something like an eye. Develops more complex structures to support that initial structure. There are developments like the multi-faceted eyes of flies, or multiple eyes facing in different directions so the organism is not just sensing light/shadow, but gets 3 dimensions, allowing it to acquire prey or avoid predators better.

[zeitgeist057]

same thing with smell and hearing. Just a single cell that detects vibrations, millennia later there are many cells detecting with surrounding structures to enhance the vibrations.

[DJB72]

You're starting from a faulty premis

Your assumption is that evolution - a scientific theory - has actually been proven. A claim often pontificated but never actually backed up.

Nevermind which religion is correct for a moment, but there are similar accounts of creation in most major beliefs where the deity creates life and the universe out of nothing.

If you start with "in the beginning, rocks" rather than "In the beginning, God" then the observable universe and life itself is far harder to grasp as a concept.

Just the existence of the universe makes no scientific sense. You can't have matter, time and space independent of each other. If you have matter but no time or space then where and when do you put it? Genesis answers that. "In the beginning" creation of time, "God created the heavens and the earth" matter and space. Simultaneous creation by intelligent design.

Evolution takes a far greater level of faith than anything in the Bible.

[NamerOfStars]

No, but denying the fossil record does.

[zeitgeist057]

Good point, yet complete failure to be able to see that religion is also pontificated and unproven, and far less supported by empirical evidence.
"Magic is a far easier explanation to believe in than some complicated explanation that requires one to actually think."

[zeitgeist057]

The existence of an all-powerful, all-knowing being that just happened to poof into existence one day is beyond any sort of reason or logic.

[lightbulb27]

we'll that's fair, one is theory, the other is faith. Best answer I heard above is "random mutation". one could argue... the science of it to some extent is also faith.

it's a curious question. The complexity of life in general, is mind boggling...

[DJB72]

Ok. Explain life.

I'll wait...

[DJB72]

@zeitgeist057 your example of God just "poof" into existence tells me your flaw. You assume God is subject to time when everything about creation says time is subject to God.

Relativity proves the closer you get to the speed of light the slower time moves. That means that AT the speed of light there's no passage of time.

Christ said "Before Abraham was, I AM" - which means either his grammar was terrible, a hypothesis not supported by ANYTHING else He said - OR His statement about being the Light of the World meant that for Him yesterday and tomorrow are the same - no passage of time for light.

And @lightbulb27 - both are actually Faith. Random mutations can't produce life. It's never been observed scientifically where two inanimate objects spontaneously combine for no explicable reason and life results.

Show me a scientific paper showing life being created in a lab from chemicals that's repeated easily and I'll consider a change. Heck, show me a dog giving birth to a kitten!

[zeitgeist057]

@DJB72 your explanations tell me your logic process is equivalent to a school age child, who believes that his thoughts manifest reality. Imagining something into existence doesn't make it exist once you get past that stage. We all played the imagination game where your friend says he has a laser, so you say you have a laser shield, then he says he has a laser shield destruction magic, and so on. Making your imaginary friend even more improbable and impossible with every new claim.

[purplepoppy]

If you look at an iguana's head you'll see a parietal eye, a third eye that can't see properly but can detect light and movement. You'll see various similar eyespots across nature and improvements in the design. Human eyes aren't as advanced compared to a lot of animals.

[FreyaRed]

Some single cell bacteria and archea can recognize light, some to flee from it others are attracted by light they need for photosynthesis.
Evolution of an eye is 5th class biology stuff.

[lightbulb27]

really? Seems not many out here got it. I sure never did.
yes, there are creatures that glow, so the cell is responding to some wavelengths. that makes sense. but how the heck it learn to transmit that light and interpret it... what a process...

[NamerOfStars]

Which time?

It's simple: you start with a spot that's somewhat light-sensitive (opsins and ion channels), so you can tell whether the sun's out or not. Then it gets more sensitive, so you can tell if the moon's out, and know whether you'll be visible to the predators that have ACTUAL eyes. Then you concentrate them in a single place, to know where the light is coming from, make that a recessed place so you can tell more precisely...

It builds on this, getting more and more sophisticated, and this becomes dominant because it gives you an evolutionary advantage at each step. Enough advantageous random mutations, and you'll get eyes as they are today.

[jahaims]

The same way all things evolve, random mutations. The ones that mutate advantageously reproduce more so the gene spreads, thus the mutation becomes part of that bloodlines gene pool.

[lightbulb27]

seems a common pattern in animals... two eyes wins!
what happened to the ones with many eyes?
oh those are flys...

[RebelinSteel]

It was around the time that really Old Bloke said ‘Let there be Light’. Before then was dark, then he said turn on the lights n realised he needed to sort those eyes things out as well. What’s the point of light of nothing has eyes.

[normalice]

Any sensitivity to light is better than none for any species at or above the surface of the ocean.

[lightbulb27]

weird how the general design seems to be one on each side. Wouldn't you want eyees in the back (lik3 guns on a B17 flying fortress) ... and on the end of each fin?
hammerheads be one variation, but not much... general design. don't make no sense to me how radiation stimulated ability to see and produce... eyeballs...

[normalice]

I don't keep track of bioogy but I'm sure people have made whole careers out of determining the various evolutionary advantages of eye positions.