Vision likely originated as simple eyespots in simple organisms. It also is traced back to jellyfish and their own simplistic eyespots, which are actually still present in some manner today. That is, jellyfish have areas of photoreceptor cells which don’t allow vision as we know it (they don’t even have brains), but they do allow a sensation of particular wavelengths of light to be perceived. These wavelengths often indicate depth (and maybe predators), which in turn may indicate food source (pelagic jellyfish don’t tend to get to plump).
Recent research has discovered the genetic pathway involved in light sensitivity in a close relative of the jellyfish.
“We determined which genetic ‘gateway,’ or ion channel, in the hydra is involved in light sensitivity,” said senior author Todd H. Oakley, assistant professor in UCSB’s Department of Ecology, Evolution and Marine Biology. “This is the same gateway that is used in human vision.”
This allows for a prediction using evolution: all organisms alive today which share a common ancestry with hydras will share this same genetic gateway. Organisms like flies, as the article points out, do not share this ancestry with vertebrates and as such do not share this genetic gateway. If they did share it, then wow. Creationists could actually trot out their improbability arguments.
“This work picks up on earlier studies of the hydra in my lab, and continues to challenge the misunderstanding that evolution represents a ladder-like march of progress, with humans at the pinnacle,” said Oakley. “Instead, it illustrates how all organisms — humans included — are a complex mix of ancient and new characteristics.”
Filed under: Evolution | Tagged: Caitlin R. Fong, Cnidarians, David Plachetzki, Evolution, eyespots, Hydra, Jellyfish, Opsin, Todd H. Oakley, Vision |
For the Sake of Science 
So based on that, what should we make of the fact that the studies of the Tribolium castaneum genome indicate it shares 126 genes with humans that it doesn’t share with other insects?
The “other insects” are five specific groups, not all insects. Furthermore, if you read the original paper, you’ll see that orthologous gene loss happens in other groups. This means there are other groups which retain certain genes or gene groups even though they are more distantly related. This is not unique to the red flour beetle.
What you’ve pointed out indicates ancestral relations which are seen when comparing two distant groups instead of when comparing two closely related groups. For whatever reason, some species have retained particular genes while others have not. Given the inordinate fascination your god apparently has with beetles, this variation, while interesting, is not some major upset to evolutionary biology.
To bring this back to the original point, I noted that the probability of two lineages sharing the same genetic pathway are slim if that pathway did not originate from a common ancestor. In the case of flies and humans, the pathway for eyesight did not originate from the same ancestor. But with the red flour beetle and the human genes, the ancestral relation is the same. The question then is why have some insects lost these genes?
“For whatever reason” indeed. You premised your claim of cnidarian relationship to vertebrates and humans on a gene they share in common. You said specifically, “This allows for a prediction using evolution: all organisms alive today which share a common ancestry with hydras will share this same genetic gateway.” I pointed out that certain beetles share certain genes with vertebrates and humans that other insects do not – and by your logic, that would mean these beetles share an ancestry with humans other insects do not. Except of course, this conclusion is nonsense. Of course you have amply told why it isn’t nonsense by delineating a clear means by which this happens – “for whatever reason”.
Ah, the precision of evolutionary thinking.
Jack Hudson, your argument is convoluted. There could be many reasons why or how an ancestral species developed. For michael to engage in that sort of speculation is absurd, and frankly I’m glad he has not. Secondly, the fact remains that some species today share similar genes. We already know that in a certain time, certain place, and for a particular purpose, the alterations to one species are not what would happen to any species. Grow up and stop this fairy tale thinking.
I think it goes without saying that, “the fact remains that some species today share similar genes” – in fact I would be quite surprised if this were not the case. I would even argue that it is necessarily the case that they do in a single self-sustaining eco-system.
But that is neither here nor there in terms of the poverty of the logic I called into question. It is circular at least, contradictory at worst.
Why you think good logic is “fairy tale thinking” is beyond me.
The premise is not a single gene, but rather a pathway. The ways by which vertebrates and insects see are markedly different and do not come down to a few ancestral genes in the way that you seem to be indicating.
It would make no sense to argue that the opsin gene of vertebrates could possibly be present in insects unless the origins of vision were also the same. They aren’t. In your scenario, however, you’ve pointed out where the ancestral relations do converge. The comparison is not analogous.
Two entirely different pathways can yield virtually the same result. For instance, vertebrate and insect eyes.
Well no Micheal, it’s not a ‘pathway’, it’s a gateway – something that controls the flow of ions controlled by the protein, opsin, the gene for which is shared by humans and cnidarians. As we have seen, humans share some genes with cnidarians, and some genes with certain beetles (not John, Paul, George or Ringo). Those same genes in those beetles are not shared with other insects. this of course doesn’t mean that the beetles therefore share a ancestor with humans that they don’t share with other insects.
What is interesting about the gene for opsin found in cnidarians (and the ion gateway it utilizes, is how little changed it appears to be in what – over 600 hundred million years of evolution?
Amazingly it works not only in this simple animal, but with little change it also happens to work as a part of a much more complex vision system. It was as if a kid tinkering with legos incidentally produced part of a jet engine. Of the course the implications of this reality are lost on Darwinists.
I’m pointing out that your claim that I “premised [my] claim of cnidarian relationship to vertebrates and humans on a gene” is not so. I rested my premise on the complex genetic pathway that exists. I then pointed out that this gateway should be present in all organisms which share common ancestry going back to hydras and jellyfish.
Your previous comparison still does not work, by the way.
Except it’s not a ‘complex genetic pathway’ it a gene for opsin. Perhaps a set of genes. If a gene, or a set of genes indicates ancestry, then the beetles with which we share 126 genes are more closely related to us than with other insects.
Vertebrate vision is based upon more than a single gene. This point goes beyond the scope of the article and the original paper.
Sure, but in this case you are basing ancestry on this single gene.
There is no ‘complex genetic pathway’. That is the point. There is a gene for opsin, which we share with a particular cnidarian.
Again, that point is an independent (correct) presumption from outside the article.