I 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.
The guest apparently runs a creationist website and they were talking about evolution. It was the last 8 minutes of the program so while I didn't catch much of it I did see the part where he was claiming that beneficial mutations are nigh near impossible.
In spite of the attempt at gaining some sort of authority by being bedecked in the lab coat obviously this guy has no clue as to what he was proclaiming with absolute certainty. FWIU while detrimental mutations outnumber beneficial ones by something like 9 to 1 (and neutral ones outnumber harmful ones by something like 10 to 1) they certainly take place and a vast assortment of them have been documented.
So much so that even some of the biggest and most influential Young Earth Creationist (YEC) organizations such as Creation Ministries International (CMI) and AnswersinGenesis (AiG) put the claim that "There are no beneficial mutations" on their "Arguments we think creationists should NOT use" web page in the "Which arguments should definitely not be used?" section (emphasis in original). Likewise with Creationwiki.
While entire books could be written stretching into many volumes just listing beneficial mutations that have been documented I'm going to make the point by just list a few that I'm personally aware of that are known to have affected humans as a whole or particular groups.
1. Let's start with the Glycophorin A somatic cell mutation which has been found in most Tibetans (87%) and rarely in their Chinese neighbors (9%). This mutation controls red blood cell production and enables them to endure extensive periods at altitudes above 7,000’ (2133 meters) without succumbing to apoplexia.
This particular example has been touted by some as representing the strongest instance of natural selection ever documented in a human population and took place in the 2,750 years since the populations split though I think the apoA-I Milano allele mutation (see #10) might be better documented.
2. A similar though different mutation has also been identified among native people living at high altitudes in the Andes. In the South American case the adaptation involves making more red blood cells, which transport oxygen to the body's tissues. For example, native people in the Peruvian Andes have higher red blood cell counts than their countrymen living at sea level.
There is yet another totally different mutation among the people native to the Ethiopian highlands that allows them to survive better at high altitude.
3. Another well known example of a beneficial mutation are those that provide lactase persistence. An allele conferring lactase persistence has evolved separately at least seven different times in the last 7000 years among pastoralist groups ranging from Northern and Eastern Europe, the Middle East, Northeast Africa and India) allowing adult humans to drink milk. This provides them with another source of food to consume that those who are lactate intolerant can not use. That would definitely come in handy during periods of decreased food supply.
4. Similar are mutations of the ADH enzymes that allow for the consumption of alcoholic beverages. While alcohol consumption (more specifically its over-consumption) is the cause of many societal ills, it provided an important benefit in early cultures. Alcohol is rich in energy, portable and is far less susceptible to spoilage than the materials that they were made from like grains in the case of beer. Moreover, it has a far lower pathogenic load than water in a pre-modern environments.
All of this means that the ability to drink alcohol allowed people to get nutritional value from food stuffs subject to spoiling or more difficult to transport. Again this is a distinct advantage over those who had no tolerance for alcohol in the time of food shortages.
5. A mutation in the FADS gene cluster that scientists thought took place some 85,000 years ago allowed humans to manufacture long chain polyunsaturated fatty acids from plant fats. This meant that early humans no longer had to rely on just one food source, fish, for brain growth and development and allowed them to be able to leave the region.
6. Yet another mutation that scientists think took place between 11-19 thousand years ago is the one that caused a decrease in pigmentation in the skin (caused lighter skin) allowing those in northern climates to increase their ability to manufacture vitamin D from sunlight.
Interestingly, a couple years ago researchers announced that evolution of skin pigmentation is still continuing strongly over the last 5000 years and fairly robustly too. The authors calculate a selective sweep of 2–10% per generation.
7. Then there is ccr5-Δ32 which changes cell surface receptors and confers a significant resistance to infection by HIV-1 and may also confer some resistance to smallpox and some plagues. Interestingly it does cause a higher susceptibility to West Nile.
FWIU, another mutation in a gene called CCR-5, which is now found in 1% of Northern Europeans, and provides complete immunity to HIV, does not have this side effect.
8. Another example of beneficial mutations are some of the family members from the village of Limone Sul Garda in northern Italy have a mutation which gives them better tolerance of HDL serum cholesterol. This mutation was traced to a single common ancestor living in the 1700's, but has now spread to dozens of descendants and as a result this family has no history of heart attacks in spite of their high-risk dietary habits.
Genetic samples from this family are now being tested for potential treatment of patients of heart disease.
9. And then there’s a family in the state of Connecticut who've been identified as having hyperdense, virtually unbreakable bones that’s been traced to a mutation that increased the function of a gene called LRP5. According to those examining the family, members with the mutation have bones reminiscent of Bruce Willis’ character in the movie “Unbreakable.” In fact one of the doctors who has studied the condition noted that "none of those people, ranging in age from 3 to 93, had ever had a broken bone."
Moreover, they also seem resistant not just to injury, but to normal age-related skeletal degeneration.
Interestingly, a different mutation to the LRP5 gene has been linked to just the opposite effect – more brittle bones.
10. One of the best known mutations is the apoA-I Milano allele mutation that has affected the apolipoprotein A1 protein found in human High-density lipoprotein (HDL), the lipoprotein particle that carries cholesterol from tissues to the liver and is associated with significantly reducing cardiovascular disease (specifically clogged arteries, heart attack, and stroke). This is due to it being more effective at removing cholesterol from cells, dissolving arterial plaques, as well as functioning as an antioxidant, preventing some of the damage from inflammation that normally occurs in arteriosclerosis.
This particular mutation was first documented in 1980 among some villagers living in northern Italy, all of who are descendants of a particular 18th century man named Giovanni Pomarelli. Synthetic versions have been manufactured and are making their way to market.
11 Very similar to apoA-I Milano allele mutation has been found in a gene called PCSK9. A 15 year study of this mutation revealed that people who possess it have an estimated 88% reduced risk of developing cardiovascular complications with apparently no obvious deleterious effects associated with very low LDL cholesterol (LDLc) levels.
Indeed the discovery of this mutation has led to a revolutionization of the field of LDLc-regulation leading to a new PCSK9-targeted class of medicines emerging that researchers say represents the biggest weapon against heart disease since the development of statins.
12. And for yet another example we’ve also identified an emerging population of tetrachromatic women who can see a bit of the normally invisible ultraviolet spectrum. For instance, the artist Concetta Antico has a genetic mutation that gave her four types of cone cell classes in her eyes (normal color vision humans only have three cone cell classes) and that her fourth cone appears to absorbs wavelengths that are described as being "reddish-orangey-yellow." The uptake is that she can see up to one hundred times more colors than a normal human being. In a way that is like the difference between someone with normal vision and a color-blind person. Some studies estimate that approximately 1% of the world's population tetrachromatic.
13. A couple years back a paper was released in Science which explains why the Inuits (formerly referred to as "Eskimos"), despite a diet that is heavily dependent upon fatty meat and fish (a diet which has long been associated with an increased risk in heart attacks and stroke) have a relatively low rate of cardiovascular disease. It appears that they have adaptive genetic mutations that allow them to better process the fats that they eat. These mutations occurred within a cluster of genes that direct construction of enzymes called fatty acid desaturases (FADS).
14. Also, a few years ago, while studying a group of elderly, overweight individuals who, by all accounts, ought to have type 2 diabetes but didn't, researchers discovered a mutation in a gene called SLC30A8 (Solute carrier family 30, member 8). Those with this mutation were found to be 65% less likely to get diabetes, even when they have risk factors like obesity due to how it affects insulin.
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 guest apparently runs a creationist website and they were talking about evolution. It was the last 8 minutes of the program so while I didn't catch much of it I did see the part where he was claiming that beneficial mutations are nigh near impossible.
In spite of the attempt at gaining some sort of authority by being bedecked in the lab coat obviously this guy has no clue as to what he was proclaiming with absolute certainty. FWIU while detrimental mutations outnumber beneficial ones by something like 9 to 1 (and neutral ones outnumber harmful ones by something like 10 to 1) they certainly take place and a vast assortment of them have been documented.
So much so that even some of the biggest and most influential Young Earth Creationist (YEC) organizations such as Creation Ministries International (CMI) and AnswersinGenesis (AiG) put the claim that "There are no beneficial mutations" on their "Arguments we think creationists should NOT use" web page in the "Which arguments should definitely not be used?" section (emphasis in original). Likewise with Creationwiki.
While entire books could be written stretching into many volumes just listing beneficial mutations that have been documented I'm going to make the point by just list a few that I'm personally aware of that are known to have affected humans as a whole or particular groups.
1. Let's start with the Glycophorin A somatic cell mutation which has been found in most Tibetans (87%) and rarely in their Chinese neighbors (9%). This mutation controls red blood cell production and enables them to endure extensive periods at altitudes above 7,000’ (2133 meters) without succumbing to apoplexia.
This particular example has been touted by some as representing the strongest instance of natural selection ever documented in a human population and took place in the 2,750 years since the populations split though I think the apoA-I Milano allele mutation (see #10) might be better documented.
2. A similar though different mutation has also been identified among native people living at high altitudes in the Andes. In the South American case the adaptation involves making more red blood cells, which transport oxygen to the body's tissues. For example, native people in the Peruvian Andes have higher red blood cell counts than their countrymen living at sea level.
There is yet another totally different mutation among the people native to the Ethiopian highlands that allows them to survive better at high altitude.
3. Another well known example of a beneficial mutation are those that provide lactase persistence. An allele conferring lactase persistence has evolved separately at least seven different times in the last 7000 years among pastoralist groups ranging from Northern and Eastern Europe, the Middle East, Northeast Africa and India) allowing adult humans to drink milk. This provides them with another source of food to consume that those who are lactate intolerant can not use. That would definitely come in handy during periods of decreased food supply.
4. Similar are mutations of the ADH enzymes that allow for the consumption of alcoholic beverages. While alcohol consumption (more specifically its over-consumption) is the cause of many societal ills, it provided an important benefit in early cultures. Alcohol is rich in energy, portable and is far less susceptible to spoilage than the materials that they were made from like grains in the case of beer. Moreover, it has a far lower pathogenic load than water in a pre-modern environments.
All of this means that the ability to drink alcohol allowed people to get nutritional value from food stuffs subject to spoiling or more difficult to transport. Again this is a distinct advantage over those who had no tolerance for alcohol in the time of food shortages.
5. A mutation in the FADS gene cluster that scientists thought took place some 85,000 years ago allowed humans to manufacture long chain polyunsaturated fatty acids from plant fats. This meant that early humans no longer had to rely on just one food source, fish, for brain growth and development and allowed them to be able to leave the region.
6. Yet another mutation that scientists think took place between 11-19 thousand years ago is the one that caused a decrease in pigmentation in the skin (caused lighter skin) allowing those in northern climates to increase their ability to manufacture vitamin D from sunlight.
Interestingly, a couple years ago researchers announced that evolution of skin pigmentation is still continuing strongly over the last 5000 years and fairly robustly too. The authors calculate a selective sweep of 2–10% per generation.
7. Then there is ccr5-Δ32 which changes cell surface receptors and confers a significant resistance to infection by HIV-1 and may also confer some resistance to smallpox and some plagues. Interestingly it does cause a higher susceptibility to West Nile.
FWIU, another mutation in a gene called CCR-5, which is now found in 1% of Northern Europeans, and provides complete immunity to HIV, does not have this side effect.
8. Another example of beneficial mutations are some of the family members from the village of Limone Sul Garda in northern Italy have a mutation which gives them better tolerance of HDL serum cholesterol. This mutation was traced to a single common ancestor living in the 1700's, but has now spread to dozens of descendants and as a result this family has no history of heart attacks in spite of their high-risk dietary habits.
Genetic samples from this family are now being tested for potential treatment of patients of heart disease.
9. And then there’s a family in the state of Connecticut who've been identified as having hyperdense, virtually unbreakable bones that’s been traced to a mutation that increased the function of a gene called LRP5. According to those examining the family, members with the mutation have bones reminiscent of Bruce Willis’ character in the movie “Unbreakable.” In fact one of the doctors who has studied the condition noted that "none of those people, ranging in age from 3 to 93, had ever had a broken bone."
Moreover, they also seem resistant not just to injury, but to normal age-related skeletal degeneration.
Interestingly, a different mutation to the LRP5 gene has been linked to just the opposite effect – more brittle bones.
10. One of the best known mutations is the apoA-I Milano allele mutation that has affected the apolipoprotein A1 protein found in human High-density lipoprotein (HDL), the lipoprotein particle that carries cholesterol from tissues to the liver and is associated with significantly reducing cardiovascular disease (specifically clogged arteries, heart attack, and stroke). This is due to it being more effective at removing cholesterol from cells, dissolving arterial plaques, as well as functioning as an antioxidant, preventing some of the damage from inflammation that normally occurs in arteriosclerosis.
This particular mutation was first documented in 1980 among some villagers living in northern Italy, all of who are descendants of a particular 18th century man named Giovanni Pomarelli. Synthetic versions have been manufactured and are making their way to market.
11 Very similar to apoA-I Milano allele mutation has been found in a gene called PCSK9. A 15 year study of this mutation revealed that people who possess it have an estimated 88% reduced risk of developing cardiovascular complications with apparently no obvious deleterious effects associated with very low LDL cholesterol (LDLc) levels.
Indeed the discovery of this mutation has led to a revolutionization of the field of LDLc-regulation leading to a new PCSK9-targeted class of medicines emerging that researchers say represents the biggest weapon against heart disease since the development of statins.
12. And for yet another example we’ve also identified an emerging population of tetrachromatic women who can see a bit of the normally invisible ultraviolet spectrum. For instance, the artist Concetta Antico has a genetic mutation that gave her four types of cone cell classes in her eyes (normal color vision humans only have three cone cell classes) and that her fourth cone appears to absorbs wavelengths that are described as being "reddish-orangey-yellow." The uptake is that she can see up to one hundred times more colors than a normal human being. In a way that is like the difference between someone with normal vision and a color-blind person. Some studies estimate that approximately 1% of the world's population tetrachromatic.
13. A couple years back a paper was released in Science which explains why the Inuits (formerly referred to as "Eskimos"), despite a diet that is heavily dependent upon fatty meat and fish (a diet which has long been associated with an increased risk in heart attacks and stroke) have a relatively low rate of cardiovascular disease. It appears that they have adaptive genetic mutations that allow them to better process the fats that they eat. These mutations occurred within a cluster of genes that direct construction of enzymes called fatty acid desaturases (FADS).
14. Also, a few years ago, while studying a group of elderly, overweight individuals who, by all accounts, ought to have type 2 diabetes but didn't, researchers discovered a mutation in a gene called SLC30A8 (Solute carrier family 30, member 8). Those with this mutation were found to be 65% less likely to get diabetes, even when they have risk factors like obesity due to how it affects insulin.
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.
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