Abstract: Charles Darwin appreciated the conceptual difficulty in accepting that an organ as wonderful as the vertebrate eye could have evolved through natural selection. He reasoned that if appropriate gradations could be found that were useful to the animal and were inherited, then the apparent difficulty would be overcome. Here, we review a wide range of findings that capture glimpses of the gradations that appear to have occurred during eye evolution, and provide a scenario for the unseen steps that have led to the emergence of the vertebrate eye.
More than 600 million years ago (Mya), early organisms evolved photoreceptors that were capable of signalling light, and that presumably mediated phototaxis, predator evasion by shadow detection or vertical migration, and the entrainment of circadian rhythms. However, it was not until the Cambrian explosion, beginning around 540 Mya, that animal body plans began evolving very rapidly[2]–[4] and image-forming eyes and visual systems emerged. The possession of advantageous capabilities or attributes, such as sight, rapid movement and armour, might have become crucial to survival, and might have led to an ‘arms race’ in the development of defensive and offensive mechanisms[5]. In the various phyla eyes evolved with diverse forms, but apparently based on certain common underlying features of patterning and development, as exemplified by genes such as PAX6 and RAX (also known as RX), which have critical roles during neurulation and brain regionalization. For accounts of the origin and interrelationship of eyes in different phyla, see REFS [6]-[10].
Here we concentrate on the origin of the vertebrate eye. We summarize results from disparate fields: the emergence of the vertebrate (camera-like) eye, the evolution of photoreceptors, the phylogeny of opsins, the development of the eye cup, and the development of the retina. We then endeavour to integrate these findings to develop a plausible and coherent sequence for vertebrate eye evolution. To begin with, we summarize current ideas regarding the origin of vertebrates and the timescale involved.
But Bill Cole swears science knows nothing about how features like eyes evolved. I guess everyone in science should just quit and find a new occupation.
I don’t know, and I don’t know why anyone would have had to mention it explicitly. Its ability to create new allele combinations is blindingly obvious.
Can you not see that?
Immediately.
I don’t dispute that; it’s impossible for me to imagine how one could get to transposable elements without studying a lot of recombination along the way. She’s famous for transposable elements.
My point is that people were studying recombination long ago. Bill might want to look up the term centiMorgan.
Bill, you’d have to have gone through ALL of the candidate evidence to credibly make a claim of “no evidence.” Since you described recombination as a “new idea,” it’s obvious that you lack even a high-school level of familiarity with the evidence.
Perhaps you should learn before pretending to have a deeper understanding than experts do? Just a thought…
I accepted for most I my life until I was exposed to the details such as long genetic sequences. I do think a lot of the theory especially adaptive evolution is solid science.
I have gone through a lot of it and I have not seen a paper explain the origin of the functional information or any model of how that would come about.
Do you think this is explained in the paper Tim cited?
Here we go again with the bog-standard ID weasel-words.
Every individual in every generation has new genetic variations = new information. The new information which provides a beneficial (or sometime neutral) function tends to be fixed in the gene pool. That’s the source of new functional information.
This makes approx. the 450th time you’ve had that explained to you.
Give an example of what you would consider “innovative”. A specific example.
For instance: "An organism did not have the ability to metabolize a particular substrate. The genomes of some of its offspring underwent a gene duplication even, and then this duplicate gene underwent mutations that allowed the organism to metabolize this substrate. This is an example of “innovation.”
I would consider that to be a clear example of innovation. But you might have a different idea.
(Or maybe this thread will just be closed, in which case sorry I was late for your party).
We have already been through this as well. You have been shown how mutations and selection produces information. All you need is for a mutation to spread through a population. This produces mutual information, the one type of information that you have cited multiple times.
I guess everyone in science should just quit and find a new occupation.