Friday, 7 January 2022

Evolution News - How Modern Humans Evolved an Improved Protein by a Simple Mutation

Modern humans developed a more effective protection against oxidative stress | Karolinska Institutet Nyheter

It's the same old story. Just when Michael J Behe and his Deception Institute masters are getting their dupes to believe they are onto something with their unintelligently designed 'devolution' hoax, along comes another scientific paper and refutes the entire half-baked notion.

Here, for example is a paper by a team led by Hugo Zeberg at Karolinska Institutet and the Max Planck Institute for Evolutionary Anthropology, and Svante Pääbo at the Max Planck Institute. In it they show that humans have a slightly modified gene for an essential protein enzyme, compared to that in other primates and, most relevantly for refuting Creationism's latest hoax, in Neanderthals.

And to make matters worse for Creationism, the mutation involves the simplest substitution in a DNA codon, which results in a substitution of one amino acid in the protein chain for another. This simple substitution does not affect the activity and stability of the enzyme but it is much better than the Neanderthal version in that it doesn't produce nearly so many free oxygen radicals in the cells, so reduces the oxidative stress.

By comparing the large majority of modern humans with the 1-2% of (mostly) south Asian carriers of the Neanderthal version, acquired through interbreeding when moderns and Neanderthals came into contact, the team were able to show that these carriers of this Neanderthal gene were much more susceptible to inflammatory and vascular diseases caused by oxidative stress.

The Karolinska Insitutet news release explains:
Very few proteins in the body have a change that makes them unique compared to the corresponding proteins in Neanderthals and apes. Researchers at the Max Planck Institute for Evolutionary Anthropology in Germany and Karolinska Institutet in Sweden have now studied one such protein, glutathione reductase, which protects against oxidative stress. They show that the risk for inflammatory bowel disease and vascular disease is increased several times in people carrying the Neanderthal variant.

What makes modern humans unique is a question that has eluded researchers for a long time. One way to approach this question is to study the proteins, or building blocks, in the body that have changes that are carried by almost all living people today and occurred after we separated from the ancestors we shared with Neanderthals about 500,000 years ago. There are around 100 proteins that have such a unique change. One of these proteins is glutathione reductase which is part of the body's defense against oxidative stress.

The study, which is published in the journal Science Advances, examines the change in glutathione reductase in detail and was led by Hugo Zeberg at Karolinska Institutet and the Max Planck Institute for Evolutionary Anthropology and Svante Pääbo at the Max Planck Institute. They show that the Neanderthal protein created more reactive oxygen radicals which are the cause of oxidative stress. It is the third protein change unique to present-day humans that has been studied so far.

Link to vascular and bowel diseases

The risk increases we see are large; several times increased risk of inflammatory bowel disease and vascular disease.

Hugo Zeberg.
The study also shows that the Neanderthal protein has passed over to present-day humans in low frequency when our ancestors mixed with them about 60,000 years ago. Today, it occurs mainly on the Indian subcontinent at an estimated frequency of 1 to 2 per cent of the population. The researchers found that people who carry the Neanderthal protein have a higher risk of developing vascular disease and inflammatory bowel disease, both diseases that are linked to oxidative stress.

The researchers can only speculate about why this particular change came to be one of the unique changes that almost all modern humans carry.

“Stopping oxidative stress is a bit like preventing something from rusting. Perhaps the fact that we are living longer has driven these changes,” says Svante Pääbo.
The team's open access paper is published open access in Science Advances:
Abstract
Glutathione reductase is a critical enzyme for preventing oxidative stress and maintaining a reduced intracellular environment. Almost all present-day humans carry an amino acid substitution (S232G) in this enzyme relative to apes and Neanderthals. We express the modern human and the ancestral enzymes and show that whereas the activity and stability are unaffected by the amino acid substitution, the ancestral enzyme produces more reactive oxygen species and increases cellular levels of transcripts encoding cytokines. We furthermore show that the ancestral enzyme has been reintroduced into the modern human gene pool by gene flow from Neanderthals and is associated with multiple traits in present-day people, including increased susceptibility for inflammatory-associated disorders and vascular disease.

Coppo Lucia; Mishra Pradeep; Siefert Nora; Holmgren Arne; Pääbo Svante; Zeberg Hugo
A substitution in the glutathione reductase lowers electron leakage and inflammation in modern humans;
Science Advances
5 Jan 2022 8(1); DOI: 10.1126/sciadv.abm1148

Copyright: © 2022 The authors. Published by American Association for the Advancement of Science.
Open access
Reprinted under a Creative Commons Attribution-NonCommercial 4.0 International license (CC BY 4.0)
The final comment by Svante Pääbo to the effect that the driver of this evolutionary change as modern humans diversified from the common ancestor they shared with Neanderthals might well be longer lifespan of moderns compared to Neanderthals, and presumably our common ancestor, is worth thinking about for a moment. One of the things that probably distinguishes modern Homo sapiens and even early archaic hominins, is longevity. As the children of modern humans need a prolonged childhood and, as hunter-gatherer family groups benefitted from someone to take care of the children, so grandparents became more and more useful. Anything which tended to lengthen the lifespan, especially beyond the menopause in females, would have benefitted those genes in the grandchildren. Grandparents would have been the repositories of the accumulated wisdom of the group before writing, so anything, such as this mutation which reduced the oxidation stress in the cells, so prolonging life, could have evolved as part of a complex of changes that resulted in longevity and post-menopausal survival - something unique to humans - would have been selected for.

The problem for Creationists, if it isn't obvious by now, is that here we have an example of at least three things that are anathema to them:
  1. A simple mutation giving rise to a very different meaning of the information, with no change in the amount of information.
  2. A mutation that can't, in any commonly-understood meaning of the word 'detrimental', be described as a detrimental mutation, and thus as some sort of 'devolution' from a notional perfection, which, according to the notion currently being pushed by Michael J Behe and the Deception Institute, all mutations are, unless they see 'inflammatory-associated disorders and vascular disease' as perfection, and their elimination as detrimental.
  3. Evidence of common descent in that the predominant version of the gene for glutathione reductase is a slight modification and in the same locus as the gene for that enzyme in Neanderthals and the other apes.
So, once again we have an incidental refutation of Creationism by scientists by simply revealing the facts which are of course entirely inconsistent with the childish notion of Creationism and entirely consistent with the scientific explanation for evolution and biodiversity.

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