Seeing Red, Independently
by MikeGeneHere's the abstract of an old paper that uncovered a nice example of convergent evolution at the molecular scale:
We have isolated and sequenced genes from the blind cave fish, Astyanaxfasciatus, that are homologous to the human red and green visual pigment genes. The data strongly suggest that, like human, these fish have one red-like visual pigment gene and multiple green-like visual pigment genes. By comparing the DNA sequences of the human and fish visual pigment genes and knowing their phylogenetic relationship, one can infer the direction of amino acid substitutions in the red and green visual pigments. The results indicate that the red pigments in human and fish evolved from the green pigment independently by identical amino acid substitutions in only a few key positions.
Yokoyama R, Yokoyama S. 1990. Convergent evolution of the red- and green-like visual pigment genes in fish, Astyanax fasciatus, and human. Proc Natl Acad Sci U S A. 87:9315-8.

























June 1st, 2007 at 11:27 pm
Mike:
Ummm… this has already been answered by biologists, Mike. We (as primates) see red so we can distinguish new leaves and ripe fruit better than our color blind brothers. I've cited numerous papers saying this very thing in the many trichromatic vision threads at ARN.
I doubt that fish evolved identical trichromatic capabilities so they could distinguish new leaves and ripe fruit. Huh.
Question: Did "red" exist before fish, birds, reptiles and/or primates evolved the sensory apparatus to perceive it? Or did "red" come into existence when life (myriad forms) independently evolved the sensory apparatus to perceive it?
The answer to that is pertinent, I think.
Comment by Joy — June 1, 2007 @ 11:27 pm
June 2nd, 2007 at 5:11 am
Wow! How homologous are these genes anyway? Apparenlty the amino acids are the same, how different are the point mutations at the nucleotide level?
Comment by Jehu — June 2, 2007 @ 5:11 am
June 2nd, 2007 at 5:55 am
From a recent study:
So yes, "red" existed already.
Comment by Raevmo — June 2, 2007 @ 5:55 am
June 2nd, 2007 at 9:15 am
Raevmo:
Of course it did, so it's interesting that life had to 'develop' by means of specified mutations the ability to perceive that which already existed. More interesting that so many widely separated kinds of life ended up developing the exact same means. Almost as if it were predestined, eh?
I like the "Seeing Red" portion of the title of this post, and note that in Chalmers' description of the nature of qualia he uses the color red - perhaps just a coincidental choice, perhaps a quale new enough in the bank of qualia to resonate in most non-color blind people.
Next question: Humans use the color red to express a consuming emotional state, which in English is phrased "seeing red." Did proto-people emotionally "see red" before they could physically see red?
Comment by Joy — June 2, 2007 @ 9:15 am
June 2nd, 2007 at 11:16 am
It would be even more interesting if life developed the ability to perceive that which did not exist.
Almost, but not quite.
I doubt it. Might the redness of blood have anything to do with it? Why do bullfighters wave red capes to "enrage" the color-blind bull?
Comment by Raevmo — June 2, 2007 @ 11:16 am
June 2nd, 2007 at 11:51 am
Raevmo:
Wow. Then the Evangelists among our atheist brethren should stop trying to assert that people's direct perceptions of spiritual realities is all about that which does not exist.
If you can't see red, blood isn't red. The red capes are flashy to those of us who can see red. If the bull can't see the color, then it's the movement (and/or the matador's attitude) that enrages him.
Comment by Joy — June 2, 2007 @ 11:51 am
May 24th, 2008 at 3:41 pm
Conant & Wagner assert (w/o argument) that convergent evolution is a potent indicator of optimal design. I thought that convergent design is a potent indicator of optimal evolution. Mike Gene?
http://www.bioc.uzh.ch/wagner/...
Comment by Rock — May 24, 2008 @ 3:41 pm