Evolution and hemoglobin

Quantum Thought doesn't support comments to posts in the blog, but e-mailing my post seems to have had the intended effect. It got his attention, and my blog was open to comments.

Problem is, his comments have been very long. So I'm dedicating a post or three to addressing the issue some more.

In his first comment to me, Norm Weatherby leads off with a classic argumentum ad verecundiam.

Please bother to check out the credentials of the Wistar institute before so readily dismissing their conclusions.

OK, they have very good credentials. So stipulated. Indeed, I stipulated as much in the title of the original post" "Wistar destroys its credibility." You can't destroy what doesn't exist.

...continued in full post...

They have very good credentials. They're still wrong.

An appeal to authority may be inappropriate in a couple of ways:

It is unnecessary. If a question can be answered by observation or calculation, an argument from authority is not needed. Since arguments from authority are weaker than more direct evidence, go look or figure it out for yourself.

I addressed two questions that have been very well examined, and the facts don't jive with the Institute's representation of them. In the contest between the Institute and direct evidence, the Wistar Institute loses. But given its credentials, it loses authoritatively.

The "authority" cited is not an expert on the issue, that is, the person who supplies the opinion is not an expert at all, or is one, but in an unrelated area.

Medicine is not evolutionary biology, any more than engineering is quantum physics. An expert in one is not likely to be an expert in the other, and if he uses his expertise in his specialty to form judgments about other fields, he can be led badly astray.

Interestingly enough, Norm seems to have surrendered on the matter of hemoglobin. Confronted with stubborn facts, he declines to address the subject.

However, I did some more reading on the subject, including a fair amount of material I located through Google.

The Wistar Institute managed to contradict well known facts about hemoglobin (but again, given the Institute's sterling credentials, let it be noted they contradicted them most authoritatively):

George Wald stood up and explained that he had done extensive research on hemoglobin also,—and discovered that if just ONE mutational change of any kind was made in it, the hemoglobin would not function properly. For example, the change of one amino acid out of 287 in hemoglobin causes sickle-cell anemia. A glutamic acid unit has been changed to a valine unit—and, as a result, 25% of those suffering with this anemia die.

[Emphasis added]

This statement is true just plain false. There's a nifty article, at Davidson College, on the subject of Hemoglobin Orthologs.

Orthologs are sequences of genes that evolved from a common ancestor and can be traced evolutionarily through different species.

Now, we may quibble with the assumption that these did in fact evolve from anything, never mind a common ancestor, but there are some very interesting facts presented in the paper. If we compare hemoglobin molecules between species, we find that there are numerous difference.

George Wald points to one example, where a glutamic acid molecule is replaced with a valine molecule, and the result is sickle-cell trait. There are a number of amino acids that are consistent across many species, and in some of those, any change causes serious a malfunction in the protein. However, there are a number of locations where you find different amino acids in the same location in different species.

For example, in humans, the fifth amino acid in the alpha subunit is proline. In a species of frog it is serine. In chickens, it is alanine. In the zebrafish, aspartate. In the rat, glutamate. In the mouse, glycine.

This is one of the more extreme examples, as each of six different species of animal has a different amino acid in the same location in this protein. Nevertheless, since all of these are examples of animals whose hemoglobin seems to work just fine, it would appear that at least six different amino acids will work in that spot.

By actual count in the paper on orthologs, 36.4% of amino acids matched across all six species. That means that the remaining 63.6% differed from the amino acid found in human hemoglobin in at least one of the other five species. Two thirds of the amino acids in this particular subunit can be changed, and the hemoglobin seems to work just fine.

In addition, the biochemistry book I studied out of a couple of decades ago mentons in passing that "many" mutations on the surface of hemoglobin are benign. They have no effect on the shape or function of the resulting protein – or at most, a minor effect.

The Wistar Institute may have very good credentials and scientific minds. However, Norm quotes two of their scientific minds making statements that are just plain wrong. Either they can't be bothered to do the research that a college biology student would have done in the course of his studies, or they're making statements that contradict what they learned in their research.

If, as Norm insists, these people know all the relevant facts, the only conclusion that remains is that they have made the conscious decision to tell us something else.