I'd rather like to know how is it that hemoglobin is also found in annelids, echinoderms, some molluscs, some arthropods, etc.
Considering what Dawkins said on this:
The dozen or so different globins inside you are descended from an ancient globin gene which, in a remote ancestor who lived about half a billion years ago, duplicated, after which both copies stayed in the genome.
‘There were then two copies of it, in different parts of the genome of all descendant animals. One copy was destined to give rise to the alpha cluster (on what would eventually become Chromosome 11 in our genome), the other to the beta cluster (on Chromosome 16)...
‘We should see the same within-genome split if we look at any other mammals, at birds, reptiles, amphibians and bony fish, for our common ancestor with all of them lived less than 500 million years ago. Wherever it has been investigated, this expectation has proved correct
I mean, if it comes from a remote ancestor 500 millions years ago, how come we also find it in yeast and root nodules of beans ? SOmeones got to help me here
I thought of convergent evolution, but can this concept really be stressed out to the point that the eight-helix folded pattern appeared multiple times with time, random mutations and natural selection ? I would love to see the probability of this happening even twice (any statistician out there ?)
It would be nice if you told us where Dawkins said that so we could put it into context.
None of the hemoglobin found in "annelids, echinoderms, some molluscs, some arthropods, etc." are chemically or structurally the same as any of the human hemoglobin. Nor is that in yeast and beans the same. Many times the protein is not true hemoglobin but only "hemoglobin like". Others are monomeric globin. The hemoglobin found in vertebrates is unique to vertebrates. However, the source of all of these may be an ancestral myoglobin.
don't new genes in a species usually originate from a duplication ?
But then again, dawkins in the example uses, he dose seem to say globin genes are only in the vertebrate family.
You're getting muddled.
According to Dawkins, there was already a globin gene. In a certain species having this gene, about 500 mya, ancestral to us, fish, reptiles, etc, the gene was duplicated.
Read what he says over again.
quote:The dozen or so different globins inside you are descended from an ancient globin gene which, in a remote ancestor who lived about half a billion years ago, duplicated, after which both copies stayed in the genome.
There were then two copies of it, in different parts of the genome of all descendant animals.