What Darwin Didn't Know

biko

Watching this on TV the other night. Very interesting program, this was about the development/evolution of eyes and claimed that eyes had only evolved once long ago and all species with eyes inherited them from this common ancestor.

The proof for this was that of all the spieces they had studied 100% had the same gene controlling the development of the eyes, PAX6 I think it was called.

nesf

I'm pretty sure squid eyes evolved "separately" to human eyes or at least branched apart far enough back for very substantial differences. The rods & cones are the other way around (i.e. the light sensitive bits are pointed out towards the light in squids versus them pointing back towards the back of the eyeball like in all other "eye-ed" creatures).

I'm not a biologist/geneticist though, so I could be wrong.

m83

Didn't see the program. What kind of conclusions were they drawing from this, if any?

taram

All types eyes I can think of today branched a long time ago (Cambrian? Wah, my brain is failing me) but there's definitely a lot of talk of a common ancestor in the textbooks. So there was a simple eye out there, then different types started to develop in parallel. IIRC, Pax6 is only for animals, and controls where the eye is located (by the brain) rather than how it actually works. It also has something to do with other homologous sensory organs in animals, all deriving from the same tissue type but afraid am drawing a blank right now on any actual detail, sleepy

lisbon_lions

Ssssh, we dont want the intelligent design people getting wind of this, our schools will be never be the same again.

AtomicHorror

I've heard it suggested a few times that eyes may have two or more common ancestors. The previously-mentioned distinction between squid type eyes and vertebrate type eyes being most often cited as evidence. If this were true then the two kinds of eyes would be an example of convergent evolution.

Caint cóir

Think you might have seen about the evolution of eyes on this show;

On BBC iPlayer, there is still time to watch 'Charles Darwin and the Tree of Life', David Attenborough's personal view on Darwin's controversial idea. Programme co-produced by The Open University.

Here's a link for it; http://www.bbc.co.uk/programmes/b00hd5mf

Capt'n Midnight

Next they will be saying that we all have similar cytochrome c genes.

http://www.uic.edu/depts/bios/evolutionmtg/abstracts.html "Development and Evolution of Eyes and Photoreceptors: From Cyanobacteria to Humans" - if we all have PAX6 then it's a very long time ago as it includes box jelly fish and algae

http://skepticwiki.org/index.php?title=Eye_Evolution&printable=yes

On the molecular level, there is a key difference between Euglena and Chlamydomonas. The photoreceptive chemical in Euglena is a blue-light-activated adenylyl cyclase[4]. But Chlamydomonas uses a rhodopsin[5], like the phototactic bacteria and archaea we cited earlier, and as can be found in your own eyes and the eyes of invertebrates.

EDIT
http://www.nationmaster.com/encyclopedia/Evolution-of-the-eye

The development of the eye is considered by most experts to be monophyletic; that is, all modern eyes, varied as they are, have their origins in a proto-eye believed to have evolved some 540 million years ago