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Are there no beneficial mutations?
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Another example of a mutation that is beneficial, possibly even essential for our survival, later leading to problems.
"Evolution gets the job done. But nobody said it was perfect." I can't remember who coined the description of biology being "gloriously messy" but that is exactly what it is -- especially when you are limited to modifying and adapting existent material.
In any case, the entire paper, "Multiple Genomic Events Altering Hominin SIGLEC Biology and Innate Immunity Predated the Common Ancestor of Humans and Archaic Hominins" can be read HERE. This is the abstract from it:
Human-specific pseudogenization of the CMAH gene eliminated the mammalian sialic acid (Sia) Neu5Gc (generating an excess of its precursor Neu5Ac), thus changing ubiquitous cell surface “self-associated molecular patterns” that modulate innate immunity via engagement of CD33-related-Siglec receptors. The Alu-fusion-mediated loss-of-function of CMAH fixed ∼2–3 Ma, possibly contributing to the origins of the genus Homo. The mutation likely altered human self-associated molecular patterns, triggering multiple events, including emergence of human-adapted pathogens with strong preference for Neu5Ac recognition and/or presenting Neu5Ac-containing molecular mimics of human glycans, which can suppress immune responses via CD33-related-Siglec engagement. Human-specific alterations reported in some gene-encoding Sia-sensing proteins suggested a “hotspot” in hominin evolution. The availability of more hominid genomes including those of two extinct hominins now allows full reanalysis and evolutionary timing. Functional changes occur in 8/13 members of the human genomic cluster encoding CD33-related Siglecs, all predating the human common ancestor. Comparisons with great ape genomes indicate that these changes are unique to hominins. We found no evidence for strong selection after the Human–Neanderthal/Denisovan common ancestor, and these extinct hominin genomes include almost all major changes found in humans, indicating that these changes in hominin sialobiology predate the Neanderthal–human divergence ∼0.6 Ma. Multiple changes in this genomic cluster may also explain human-specific expression of CD33rSiglecs in unexpected locations such as amnion, placental trophoblast, pancreatic islets, ovarian fibroblasts, microglia, Natural Killer(NK) cells, and epithelia. Taken together, our data suggest that innate immune interactions with pathogens markedly altered hominin Siglec biology between 0.6 and 2 Ma, potentially affecting human evolution.
I'm always still in trouble again
"You're by far the worst poster on TWeb" and "TWeb's biggest liar" --starlight (the guy who says Stalin was a right-winger)
"Overall I would rate the withdrawal from Afghanistan as by far the best thing Biden's done" --Starlight
"Of course, human life begins at fertilization that’s not the argument." --Tassman
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Originally posted by lee_merrill View PostNot if you can argue that degradative mutations predominate in selection.
No, Behe doesn't call any modification "degrading". He says that most variations that increase fitness are degradative.
Blessings,
Lee
Glendower: I can call spirits from the vasty deep.
Hotspur: Why, so can I, or so can any man;
But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:
go with the flow the river knows . . .
Frank
I do not know, therefore everything is in pencil.
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Originally posted by lee_merrill View PostBut I need specific references!
Blessings,
LeeGlendower: I can call spirits from the vasty deep.
Hotspur: Why, so can I, or so can any man;
But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:
go with the flow the river knows . . .
Frank
I do not know, therefore everything is in pencil.
Comment
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Originally posted by rogue06 View PostI was switching through the channels this morning and as I came to one of the local religious channels I noticed that the host of the show was talking to a man wearing a lab coat. Since folks don't generally go around wearing lab coats it caught my interest so I stopped to see what was going on.
15. And the one that gets evolution deniers all worked up are the various mutations that confer resistance to malaria. Nearly everyone is aware of the sickle cell allele which confers resistance to malarial infections if you carry one copy of the allele but causes sickle cell anemia if you carry two copies. It's a good example of balancing selection. And even those with sickle cell anemia are considerably more likely to survive long enough to reproduce than those suffering from malaria.
What many are not aware of is that there are other alleles which confer resistance. The HbC variant for hemoglobin confers a 29% reduction in risk for malarial infection if you have one copy but a 93% risk reduction if you have two copies. The anemia resulting from the double copy of this gene variant is very mild in contrast to the debilitating effects of sickle cell.
Then there is the various types of Thalassemia. While they all have negative effects (bone deformities, and cardiovascular illness like anemia) it also confers a degree of protection against malaria (specifically, malaria caused by the protozoan parasite Plasmodium falciparum) and those with β-thalassemia apparently have some protection against coronary heart disease.
Finally, a single genetic mutation protects some African children from the deadly symptoms of malaria. The mutation occurs in the gene NOS2 that encodes an enzyme to produce the gas nitric oxide -- something that is present throughout the human body. The mutation is a polymorphism, a single letter change in DNA. It causes cells to ramp up production of the gas, which is thought to protect people against malaria.
Children in Tanzania and Kenya who have the mutation are much less likely to develop the disease than children who do not, with one study discovering that those with the mutation living in Tanzania were nearly 90% less likely to develop severe malaria than individuals without the mutation.
The entire paper, Evolution of immune genes is associated with the Black Death can be read by clicking the link while the abstract is also available below
Abstract
Infectious diseases are among the strongest selective pressures driving human evolution1,2. This includes the single greatest mortality event in recorded history, the first outbreak of the second pandemic of plague, commonly called the Black Death, which was caused by the bacterium Yersinia pestis3. This pandemic devastated Afro-Eurasia, killing up to 30–50% of the population4. To identify loci that may have been under selection during the Black Death, we characterized genetic variation around immune-related genes from 206 ancient DNA extracts, stemming from two different European populations before, during and after the Black Death. Immune loci are strongly enriched for highly differentiated sites relative to a set of non-immune loci, suggesting positive selection. We identify 245 variants that are highly differentiated within the London dataset, four of which were replicated in an independent cohort from Denmark, and represent the strongest candidates for positive selection. The selected allele for one of these variants, rs2549794, is associated with the production of a full-length (versus truncated) ERAP2 transcript, variation in cytokine response to Y. pestis and increased ability to control intracellular Y. pestis in macrophages. Finally, we show that protective variants overlap with alleles that are today associated with increased susceptibility to autoimmune diseases, providing empirical evidence for the role played by past pandemics in shaping present-day susceptibility to disease.
Last edited by rogue06; 11-03-2022, 06:29 AM.
I'm always still in trouble again
"You're by far the worst poster on TWeb" and "TWeb's biggest liar" --starlight (the guy who says Stalin was a right-winger)
"Overall I would rate the withdrawal from Afghanistan as by far the best thing Biden's done" --Starlight
"Of course, human life begins at fertilization that’s not the argument." --Tassman
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Are you aware of the beneficial mutation observed during an experiment being run by the Discovery Institute?Last edited by Roy; 11-03-2022, 07:29 AM.Jorge: Functional Complex Information is INFORMATION that is complex and functional.
MM: First of all, the Bible is a fixed document.
MM on covid-19: We're talking about an illness with a better than 99.9% rate of survival.
seer: I believe that so called 'compassion' [for starving Palestinian kids] maybe a cover for anti Semitism, ...
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I probably should include this one as well, which I posted about in 2017
Originally posted by rogue06 View PostIt appears that the people who live in the Quebrada Camarones region of Chiles Atacama desert have evolved a mutation that allows them to drink the water with high levels of arsenic (over 100 times the World Health Organizations safe limit) in it without ill effect.
As an article in New Scientist explains:
The body uses an enzyme called AS3MT to incorporate arsenic in two compounds, monomethylarsonic (MMA) acid and dimethylarsinic (DMA) acid. People who metabolise arsenic more efficiently convert more of it into the less toxic, more easily expelled DMA.
Mario Apata of the University of Chile in Santiago and his colleagues looked at variations in the gene coding for AS3MT in nearly 150 people from three regions of the country. They found higher frequencies of the protective variants in people from Camarones: 68 per cent there had them, as opposed to just 48 and 8 per cent of people in the other two. Our data suggest that a high arsenic metabolization capacity has been selected as an adaptive mechanism in these populations in order to survive in an arsenic-laden environment, the researchers conclude (American Journal of Physical Anthropology, doi.org/bz4s).
The variants that protect the Camarones people are called single nucleotide polymorphisms changes in a single DNA letter of the genetic code. Anthropologist Lorena Madrigal of the University of South Florida in Tampa says these are such tiny mutations that they arent telling us exactly how the changes affect the enzyme molecule and its detoxifying effects.
Previous studies found similar mutations in the AS3MT gene that contribute to improved arsenic metabolisation in Vietnam and Argentina. Sequencing the entire chromosomal region around this gene could reveal more, but theres still a long way to go before we fully understand the molecular mechanism for how arsenic resistance works.
Though its a fascinating example of what appears to be contemporary evolution in humans, it also underscores the water quality problems that many populations face, says Madrigal. And many may not be able to evolve to deal with it.
I'm always still in trouble again
"You're by far the worst poster on TWeb" and "TWeb's biggest liar" --starlight (the guy who says Stalin was a right-winger)
"Overall I would rate the withdrawal from Afghanistan as by far the best thing Biden's done" --Starlight
"Of course, human life begins at fertilization that’s not the argument." --Tassman
Comment
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Originally posted by rogue06 View PostI probably should include this one as well, which I posted about in 2017
Jorge: Functional Complex Information is INFORMATION that is complex and functional.
MM: First of all, the Bible is a fixed document.
MM on covid-19: We're talking about an illness with a better than 99.9% rate of survival.
seer: I believe that so called 'compassion' [for starving Palestinian kids] maybe a cover for anti Semitism, ...
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Originally posted by Roy View PostI wonder if those variants exist in Bangladesh.
I'm always still in trouble again
"You're by far the worst poster on TWeb" and "TWeb's biggest liar" --starlight (the guy who says Stalin was a right-winger)
"Overall I would rate the withdrawal from Afghanistan as by far the best thing Biden's done" --Starlight
"Of course, human life begins at fertilization that’s not the argument." --Tassman
Comment
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Originally posted by rogue06 View PostI've heard that portions of the country have water with a high arsenic content, are those drinking it suffering no deleterious effects?
(The problem is not that the water there has a high arsenic content, it's that dense populations are using so much water that wells are having to be deepened into arsenic bearing strata.)Last edited by Roy; 11-05-2022, 08:22 AM.Jorge: Functional Complex Information is INFORMATION that is complex and functional.
MM: First of all, the Bible is a fixed document.
MM on covid-19: We're talking about an illness with a better than 99.9% rate of survival.
seer: I believe that so called 'compassion' [for starving Palestinian kids] maybe a cover for anti Semitism, ...
Comment
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Originally posted by Roy View PostNo, they're suffering lots of deleterious effects. Those variants would, if they exist there, be highly favoured.
(The problem is not that the water there has a high arsenic content, it's that dense populations are using so much water that wells are having to be deepened into arsenic bearing strata.)
I'm always still in trouble again
"You're by far the worst poster on TWeb" and "TWeb's biggest liar" --starlight (the guy who says Stalin was a right-winger)
"Overall I would rate the withdrawal from Afghanistan as by far the best thing Biden's done" --Starlight
"Of course, human life begins at fertilization that’s not the argument." --Tassman
Comment
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An article discussing several beneficial mutations in humans, including a few not previously mentioned
I'm always still in trouble again
"You're by far the worst poster on TWeb" and "TWeb's biggest liar" --starlight (the guy who says Stalin was a right-winger)
"Overall I would rate the withdrawal from Afghanistan as by far the best thing Biden's done" --Starlight
"Of course, human life begins at fertilization that’s not the argument." --Tassman
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