mind not blown !
your guy is dead wrong besides being dead. so that information is not current.
example of benificial mutations in humans.• Apolipoprotein AI-Milano. Heart disease is one of the scourges of industrialized countries. It's the legacy of an evolutionary past which programmed us to crave energy-dense fats, once a rare and valuable source of calories, now a source of clogged arteries. But there's evidence that evolution has the potential to deal with it.
All humans have a gene for a protein called Apolipoprotein AI, which is part of the system that transports cholesterol through the bloodstream. Apo-AI is one of the HDLs, already known to be beneficial because they remove cholesterol from artery walls. But a small community in Italy is known to have a mutant version of this protein, named Apolipoprotein AI-Milano, or Apo-AIM for short. Apo-AIM is even more effective than Apo-AI at removing cholesterol from cells and dissolving arterial plaques, and additionally functions as an antioxidant, preventing some of the damage from inflammation that normally occurs in arteriosclerosis. People with the Apo-AIM gene have significantly lower levels of risk than the general population for heart attack and stroke, and pharmaceutical companies are looking into marketing an artificial version of the protein as a cardioprotective drug.
There are also drugs in the pipeline based on a different mutation, in a gene called PCSK9, which has a similar effect. People with this mutation have as much as an 88% lower risk of heart disease.
• Increased bone density. One of the genes that governs bone density in human beings is called low-density lipoprotein receptor-related protein 5, or LRP5 for short. Mutations which impair the function of LRP5 are known to cause osteoporosis. But a different kind of mutation can amplify its function, causing one of the most unusual human mutations known.
This mutation was first discovered fortuitously, when a young person from a Midwest family was in a serious car crash from which they walked away with no broken bones. X-rays found that they, as well as other members of the same family, had bones significantly stronger and denser than average. (One doctor who's studied the condition said, "None of those people, ranging in age from 3 to 93, had ever had a broken bone.") In fact, they seem resistant not just to injury, but to normal age-related skeletal degeneration. Some of them have benign bony growths on the roof of their mouths, but other than that, the condition has no side effects - although, as the article notes dryly, it does make it more difficult to float. As with Apo-AIM, some drug companies are researching how to use this as the basis for a therapy that could help people with osteoporosis and other skeletal diseases.
• Malaria resistance. The classic example of evolutionary change in humans is the hemoglobin mutation named HbS that makes red blood cells take on a curved, sickle-like shape. With one copy, it confers resistance to malaria, but with two copies, it causes the illness of sickle-cell anemia. This is not about that mutation.
As reported in 2001 (see also), Italian researchers studying the population of the African country of Burkina Faso found a protective effect associated with a different variant of hemoglobin, named HbC. People with just one copy of this gene are 29% less likely to get malaria, while people with two copies enjoy a 93% reduction in risk. And this gene variant causes, at worst, a mild anemia, nowhere near as debilitating as sickle-cell disease.
• Tetrachromatic vision. Most mammals have poor color vision because they have only two kinds of cones, the retinal cells that discriminate different colors of light. Humans, like other primates, have three kinds, the legacy of a past where good color vision for finding ripe, brightly colored fruit was a survival advantage.
The gene for one kind of cone, which responds most strongly to blue, is found on chromosome 7. The two other kinds, which are sensitive to red and green, are both on the X chromosome. Since men have only one X, a mutation which disables either the red or the green gene will produce red-green colorblindness, while women have a backup copy. This explains why this is almost exclusively a male condition.
But here's a question: What happens if a mutation to the red or the green gene, rather than disabling it, shifts the range of colors to which it responds? (The red and green genes arose in just this way, from duplication and divergence of a single ancestral cone gene.)
To a man, this would make no real difference. He'd still have three color receptors, just a different set than the rest of us. But if this happened to one of a woman's cone genes, she'd have the blue, the red and the green on one X chromosome, and a mutated fourth one on the other... which means she'd have four different color receptors. She would be, like birds and turtles, a natural "tetrachromat", theoretically capable of discriminating shades of color the rest of us can't tell apart. (Does this mean she'd see brand-new colors the rest of us could never experience? That's an open question.)
And we have evidence that just this has happened on rare occasions. In one study of color discrimination, at least one woman showed exactly the results we would expect from a true tetrachromat.
Image credit: Wikimedia Commons
I don't pretend to be an expert on genomics, but please enlighten me how they tell the people in the community in Italy don't have the original form of the gene and the rest of us don't have the harmful mutation? Basically, your argument is based on an unproven assumption that humans crave certain foods based on a speculative evolutionary past.
wrong! do you mean how do the geneticists know that that community has it?
or how did they break the news to them? the same applies to the us part too.
as to the second and dumbest part of that statement:Evolving to Eat Mush": How Meat Changed Our BodiesHillary Mayell
for National Geographic News
February 18, 2005
Meat-eating has impacted the evolution of the human body, scientists reported today at the American Association for the Advancement of Science's annual meeting in Washington, D.C.
Our fondness for a juicy steak triggered a number of adaptations over countless generations. For instance, our jaws have gotten smaller, and we have an improved ability to process cholesterol and fat.
"It's really amazing what we know now that we didn't know 15 or 20 years ago," said Mark Teaford, a professor at Baltimore's Johns Hopkins University. Teaford helped organize a panel discussion on human diet from a number of perspectives:
• How did the ability to eat meat shape the evolution of humans?
• What can we learn about early humans from tooth shape?
Carnivorous humans go back a long way. Stone tools for butchering meat, and animal bones with corresponding cut marks on them, first appear in the fossil record about 2.5 million years ago.
How Did Meat-Eating Start?
Some early humans may have started eating meat as a way to survive within their own ecological niche.
Competition from other species may be a key element of natural selection that has molded anatomy and behavior, according to Craig B. Stanford, an ecologist at the University of Southern California (USC).
Stanford has spent years visiting the Bwindi Impenetrable Forest National Park in Uganda, Africa, studying the relationship between mountain gorillas and chimpanzees.
"It's the only forest where mountain gorillas and chimps both live," he said. "We're trying to understand the ecological relationship—do they compete for food, for nesting sites?"
The key difference between chimps and gorillas ecologically is that chimps eat meat and gorillas don't. A total herbivore is able to coexist with an omnivore because they have significantly different diets.
"Evolving to Eat Mush": How Meat Changed Our Bodies<< Back to Page 1 Page 2 of 2
"From there we can extrapolate back to what two species of early humans may have done vis-Ã -vis each other two or three million years ago," Stanford said.
"We have an obsession today with fat and cholesterol because we can go to the market and stuff ourselves with it," Stanford said. "But as a species we are relatively immune to the harmful effects of fat and cholesterol. Compared to the great apes, we can handle a diet that's high in fat and cholesterol, and the great apes cannot.
"Even though we have all these problems in terms of heart disease as we get older, if you give a gorilla a diet that a meat-loving man might eat in Western society, that gorilla will die when it's in its twenties; a normal life span might be 50. They just can't handle that kind of diet."
Diet and Teeth
Tool-use no doubt helped early humans in butchering their dinners. But there is evidence that the advance to cooking and using knives and forks is leading to crooked teeth and facial dwarfing in humans.
Today it's relatively rare for someone to have perfectly straight teeth (without having been to the orthodontist). Our wisdom teeth don't have room to fit in the jaw and sometimes don't form at all, and the propensity to develop gum disease is on the increase.
"Virtually any mammalian jaw in the wild that you look at will be a perfect occlusion—a very nice Hollywood-style dentition," said Peter Lucas, the author of Dental Functional Morphology and a visiting professor at George Washington University in Washington, D.C. "But when it comes to humans, the ideal occlusion [the way teeth fit together] is virtually never seen. It's really the only body part that regularly needs attention and surgery."
Lucas argues that the mechanical process of chewing, combined with the physical properties of foods in the diet, will drive tooth, jaw, and body size, particularly in human evolution.
Essentially, by cooking our food, thereby making it softer, we no longer need teeth big enough to chow down on really tough particles. By using knives and forks to cut food into smaller pieces, we no longer need a large enough jaw to cram in big hunks of food.
"We're evolving to eat mush," said Bernard Wood, a paleoanthropologist at George Washington University.
"Evolving to Eat Mush": How Meat Changed Our Bodies