evolution of the eye

[vincentfromyay]

1. is there a theory (or is it known) as to what constitutes the most basic 'eye' in our evolutionary history? is it a single light sensitive cell for example? or something even more basic than that? or is there only speculation on the matter?

 

2. am i correct in believing that for this 'basic eye' to have appeared on the scene the following must have taken place; an organism with no 'eye' whatsover must have 'given birth' to an organism with the 'basic eye'?

 

3. if the above is correct, then am i correct in believing that this process must have involved only one mutation? and if so, is that plausible? or is it knowable? demonstrable?

 

thanks. and please bear with my ignorance as i have no formal education in biology (but i am keen to learn).

[ydoaPs]

1. is there a theory (or is it known) as to what constitutes the most basic 'eye' in our evolutionary history? is it a single light sensitive cell for example? or something even more basic than that? or is there only speculation on the matter?

 

 

There are actually "living fossils" of every stage of eye evolution from a single light-sensitive cell to our eyes.

[vincentfromyay]

ah. thanks. do you know which organism then has the most 'basic eye'? and do you have any thoughts on my other questions?

 

 

[Pantaz]

I believe there are some deep-dwelling ocean creatures with rudimentary light-sensing organs.

[Ophiolite]

Once again wikipedia comes to our aid: http://en.wikipedia.org/wiki/Evolution_of_the_eye

 

They note that "The earliest predecessors of the eye were photoreceptor proteins that sense light, found even in unicellular organisms, called "eyespots". Eyespots can only sense ambient brightness: they can distinguish light from dark, sufficient for photoperiodism and daily synchronization of circadian rhythms."

[vincentfromyay]

thanks pantaz.

 

thanks ophiolite. so, photoreceptor proteins..? even more basic than an actual light-sensitive cell. any thoughts on the mutation question? could a species have gone from having no 'eye' whatsoever to having something like photoreceptor proteins in one generation?

[iNow]

Concise explanation about the evolution of the eye, accessible even to those with zero background in biology.

 

Edited October 25, 2012 by iNow

[vincentfromyay]

thanks iNow, i enjoyed that. but i'm still no nearer having my question answered regarding mutations. what is required for going from no eye to the most basic eye in terms of mutation? if an eyeless progentitor has zero genetic info for an eye, how much mutation is required for its progeny to have a basic eye?

[Moontanman]

thanks iNow, i enjoyed that. but i'm still no nearer having my question answered regarding mutations. what is required for going from no eye to the most basic eye in terms of mutation? if an eyeless progentitor has zero genetic info for an eye, how much mutation is required for its progeny to have a basic eye?

 

 

I think you are looking for something that never existed. The eye spot on microorganisms resulted from light sensitive proteins that already had some other function in the microbe. Microbes in some environments that could detect light had an advantage and so left more progeny than those that did not. From that you would see slow advance to microbes that kept most of their light sensitive proteins in one place as in an eyespot. The more concentrated they were the better they detected light. As long as detecting light was advantageous natural selection would select for this trait.

 

The eye has evolved independently several times in several lineages of animals. But the light sensitive proteins came first in many different microbes, the ability to detect light and dark is advantageous in many environments in many ways and natural selection has amplified this over the billions of years living creatures have existed.

 

The idea that an organism without genes for an eye suddenly developed genes for an eye or produced an organism with an eye is mistaken. At no time would you see an animal with no eyes give birth to one that does...

Edited October 25, 2012 by Moontanman

[CharonY]

The simplest photosensors essentially consist of proteins that are able to absorb photons and elicit regulatory changes within the cell. As such the most basic transition could be from a precursor (membrane) protein towards something with enhanced photosensitivity, for example.

[Appolinaria]

http://news.bbc.co.uk/2/hi/sci/tech/7815540.stm

 

This is pretty interesting. Some mollusks use mirrors, and some a lens. Our common ancestor was a worm.

[STeve555]

Why are people so hung up about "intelligent design" freaks who's final latching resort on to theism consists of the unexplained "mystery" of coagulation of blood and the so called complex nature of the human eye?

 

If that is your only 2 dragons from keeping you from entering the portal of atheism, why not go all the way just right now?

 

Even if the coagulation of blood was found to be divine by nature, all other processes in nature would prove counterintuitive by now.

 

Why are people so desperate to believe pinnochio is real, till you feed him to the bbq and see his nose burn and roast a hamburger on its coal glowing residue

 

 

Thanatophobia? Perhaps?

Edited October 25, 2012 by STeve555

[StringJunky]

Why are people so hung up about "intelligent design" freaks who's final latching resort on to theism consists of the unexplained "mystery" of coagulation of blood and the so called complex nature of the human eye?

 

If that is your only 2 dragons from keeping you from entering the portal of atheism, why not go all the way just right now?

 

Even if the coagulation of blood was found to be divine by nature, all other processes in nature would prove counterintuitive by now.

 

Why are people so desperate to believe pinnochio is real, till you feed him to the bbq and see his nose burn and roast a hamburger on its coal glowing residue

 

 

Thanatophobia? Perhaps?

 

Where is the "religion" in this conversation?