Joined: 07 Feb 2007 {Posts: 1829 } Location: Lookin DC Metro, Feelin Geneva
Posted: Wed 11 Feb 2009 15:19 Post subject: They Don't Make Homo Sapiens Like They Used To
Quote:
For decades the consensus view—among the public as well as the world’s preeminent biologists—has been that human evolution is over. Since modern Homo sapiens emerged 50,000 years ago, “natural selection has almost become irrelevant” to us, the influential Harvard paleontologist Stephen Jay Gould proclaimed. “There have been no biological changes. Everything we’ve called culture and civilization we’ve built with the same body and brain.” This view has become so entrenched that it is practically doctrine. Even the founders of evolutionary psychology, Leda Cosmides and John Tooby, signed on to the notion that our brains were mostly sculpted during the long period when we were hunter-gatherers and have changed little since. “Our modern skulls house a Stone Age mind,” they wrote in a background piece on the Center for Evolutionary Psychology at the University of California at Santa Barbara.
So to suggest that humans have undergone an evolutionary makeover from Stone Age times to the present is nothing short of blasphemous. Yet a team of researchers has done just that. They find an abundance of recent adaptive mutations etched in the human genome; even more shocking, these mutations seem to be piling up faster and ever faster, like an avalanche. Over the past 10,000 years, their data show, human evolution has occurred a hundred times more quickly than in any other period in our species’ history.
The new genetic adaptations, some 2,000 in total, are not limited to the well-recognized differences among ethnic groups in superficial traits such as skin and eye color. The mutations relate to the brain, the digestive system, life span, immunity to pathogens, sperm production, and bones—in short, virtually every aspect of our functioning.
Many of these DNA variants are unique to their continent of origin, with provocative implications. “It is likely that human races are evolving away from each other,” says University of Utah anthropologist Henry Harpending, who coauthored a major paper on recent human evolution. “We are getting less alike, not merging into a single mixed humanity.”
Harpending theorizes that the attitudes and customs that distinguish today’s humans from those of the past may be more than just cultural, as historians have widely assumed. “We aren’t the same as people even a thousand or two thousand years ago,” he says. “Almost every trait you look at is under strong genetic influence.”
Not surprisingly, the new findings have raised hackles. Some scientists are alarmed by claims of ethnic differences in temperament and intelligence, fearing that they will inflame racial sensitivities. Other researchers point to limitations in the data. Yet even skeptics now admit that some human traits, at least, are evolving rapidly, challenging yesterday’s hallowed beliefs.
A BONE TO PICK
Bones don’t lie. John Hawks of the University of Wisconsin at Madison likes evidence he can put his hands on, so he takes me on a tour of the university’s bone laboratory. There, the energetic 36-year-old anthropologist unlocks a glass case and begins arranging human skulls and other skeletal artifacts—some genuine fossils, others high-quality reproductions—on a counter according to their age. Gesturing toward these relics, which span the past 35,000 years, Hawks says, “You don’t have to look hard to see that teeth are getting smaller, skull size is shrinking, stature is getting smaller.”
These overriding trends are similar in many parts of the world, but other changes, especially over the past 10,000 years, are distinct to specific ethnic groups. “These variations are well known to forensic anthropologists,” Hawks says as he points them out: In Europeans, the cheekbones slant backward, the eye sockets are shaped like aviator glasses, and the nose bridge is high. Asians have cheekbones facing more forward, very round orbits, and a very low nose bridge. Australians have thicker skulls and the biggest teeth, on average, of any population today. “It beats me how leading biologists could look at the fossil record and conclude that human evolution came to a standstill 50,000 years ago,” Hawks says.
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By his account, Hawks’s theory of accelerated human evolution owes its genesis to what he could see with his own eyes. But his radical view was also influenced by newly emerging genetic data. Thanks to stunning advances in sequencing and deciphering DNA in recent years, scientists had begun uncovering, one by one, genes that boost evolutionary fitness. These variants, which emerged after the Stone Age, seemed to help populations better combat infectious organisms, survive frigid temperatures, or otherwise adapt to local conditions. And they were popping up with surprising frequency.
Taken together, the skeletal and genetic evidence convinced Hawks that the ruling “static” view of recent human evolution was not only wrong but also quite possibly the opposite of the truth. He discussed his ideas with Harpending, his former postdoc adviser at the University of Utah, and Gregory Cochran, a physicist and adjunct professor of anthropology there. They both agreed with Hawks’s interpretation. But why, they wondered, might evolution be picking up speed? What could be fueling the trend?
Then one day, as Hawks and Cochran mulled over the matter in a phone conversation, inspiration struck. “At exactly the same moment, both of us realized, gee, there’s a lot more people on the planet in recent times,” Hawks recalls. “In a large population you don’t have to wait so long for the rare mutation that boosts brain function or does something else desirable.”
The three scientists reviewed the demographic data. Ten thousand years ago, there were fewer than 10 million people on earth. That figure soared to 200 million by the time of the Roman Empire. Since around 1500 the global population has been rising exponentially, with the total now surpassing 6.7 billion. Since mutations are the fodder on which natural selection acts, it stands to reason that evolution might happen more quickly as our numbers surge. “What we were proposing was nothing new to animal breeders of the 19th century,” Cochran notes. “Darwin himself emphasized the importance of maintaining a large herd for selecting favorable traits.”
The logic behind the notion was undeniably simple, but at first glance it seemed counterintuitive. The genomes of any two individuals on the planet are more than 99.5 percent the same. Put another way, less than 0.5 percent of our DNA varies across the globe. That is often taken to mean that we have not evolved much recently, Cochran says, “but keep in mind that the human and chimp genomes differ by only about 1 to 2 percent—and nobody would call that a minor difference. None of this conflicts with the idea that human evolution might be accelerating.”
CULTURE SHOCK
If their hunch was correct, the scientists wondered a few years back, how could they prove it? As it turned out, it was an opportune time to pose that question.
For decades theories about human evolution had proliferated despite the absence of much, if any, hard evidence. But now there were finally human genetic data banks large enough to allow the scientists to put their assumptions to the test. One of these, the International Haplotype Map, cataloged differences in DNA collected from 270 people of Japanese, Han Chinese, Nigerian, and northern European descent. Moreover, Harpending knew two geneticists—Robert Moyzis of the University of California at Irvine, and Eric Wang of Veracyte Inc. in South San Francisco—who were at the forefront of developing new computational methods for mining this data to estimate the rate of evolution. Harpending contacted them to see if they would be willing to collaborate on a study.
Human races are evolving away from each other. We are getting less alike, not merging into a single mixed humanity.
The West Coast scientists were intrigued. On the basis of their own preliminary data, they, too, suspected that the pace of human evolution was accelerating. But they had arrived at the same crossroads by a different route. “We were focused on cultural shifts as a prime driving force of our evolution,” Moyzis says. As he explains it, an exceptional period in the history of our species occurred about 50,000 years ago. Humans were pouring forth from Africa and fanning out across the globe, eventually taking up residence in niches as diverse as the Arctic Circle, the rain forests of the Amazon, the foothills of the Himalayas, and the Australian outback. Improvements in clothing, shelter, and hunting techniques paved the way for this expansion.
Experts agree on that much but then part ways. These innovations, prominent evolutionary theorists insist, insulated us from the relentless winnowing of natural selection, thereby freeing us from the Darwinian rat race. But Moyzis and Wang looked at the same developments and came to the opposite conclusion. In our far-flung domains, they point out, humans presumably encountered starkly different selective forces as they adjusted to novel foods, predators, climates, and terrains. And as we became more innovative, the pressure to change only intensified. “If you’re a human, what is your environment but culture?” Moyzis asks. “The faster our ingenuity alters our habitat, the quicker we have to adapt in response.”
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As for the role of population size in spurring our evolution, he and Wang had not given it much thought, but they saw the idea as complementary to their own view, since cultural innovations allowed more people to survive. So when Harpending’s group came calling, Moyzis says, “we were happy to combine ideas and work together.”
To study natural selection, the team combed the International Haplotype Map for long stretches of DNA flanked by a single nucleotide polymorphism (SNP, or “snip”)—that is, an altered base, or “letter,” in the genetic alphabet. When the exact same genetic block is present in at least 20 percent of a population, according to the scientists, it indicates that something about that block has conferred a survival advantage; otherwise, it would not have become so prevalent. Because genes are reshuffled with each generation, Moyzis adds, the presence of large unchanged blocks of DNA means they were probably inherited recently. In the parlance of scientists, it is “a signature of natural selection.”
Scanning genomes in the haplotype map for these clues, the researchers discovered that 7 percent of human genes fit the profile of a recent adaptation, with most of the change happening from 40,000 years ago to the present. As predicted, these apparent adaptations occurred at a rate that jumped almost exponentially in prevalence as the human population exploded. To rule out the prevailing view—that our evolution has proceeded at a steady rate all along—the scientists ran an additional check. They performed a computer simulation to see what would have happened if humans had evolved at modern rates ever since we diverged from chimpanzees 6 million years ago. The steady-state test led to a nonsensical result: The difference between the two species today would be 160 times greater than it actually is. To Moyzis and the others, the results confirmed that human evolution had only recently hit the accelerator.
MORPHING AT HIGH SPEED
All of these findings mesh beautifully with the notion that cultural and demographic shifts sparked our transformation. Our exodus out of Africa, for example, paved the way for one of the most obvious markers of race, skin hue. As scientists widely recognize, paler complexions are a genetic adjustment to low light: People with dark skin have trouble manufacturing vitamin D from ultraviolet radiation in northern latitudes, which makes them more susceptible to serious bone deformities. Consequently, Europeans and Asians over the last 20,000 years evolved lighter skin through two dozen different mutations that decrease production of the skin pigment melanin.
Similarly, the gene for blue eyes codes for paler skin coloring in many vertebrates and hence might have piggybacked along with lighter skin. Clearly something made blue eyes evolutionarily advantageous in some environments. “No one on earth had blue eyes 10,000 years ago,” Hawks says.
The transition to an agrarian existence after hundreds of thousands of years of hunting and gathering was another key catalyst of evolution. Once people began keeping cattle herds, for example, it became an advantage to derive nutrient calories from milk throughout life rather than only as an infant or toddler suckling at its mother’s breast. A mutation that arose about 8,000 years ago in northern Europe, Hawks says, allowed adults to digest lactose (the main sugar in milk), and it propagated rapidly, allowing the rise of the modern dairy industry. Today the gene for lactose digestion is present in 80 percent of Europeans but in just 20 percent of Asians and Africans.
Agriculture may have opened up other pathways for evolution by supporting an ever-growing population that eventually began to congregate in the first cities. In crowded, filthy quarters, pathogens spread like wildfire. Suddenly there were epidemics of smallpox, cholera, typhus, and malaria, diseases unknown to hunter-gatherers, and so began an evolutionary arms race to fend off the assault through superior immunity.
“The clearest example of that is malaria,” Hawks says. “The disease is about 35,000 years old, with the most lethal form of it just 5,000 years old.” Yet in sub-Saharan Africa and other regions where it is endemic, “people have already developed 25 new genes that protect against malaria, including the Duffy blood type, an entirely new blood group,” he notes. More recently, HIV resistance has appeared due to a genetic mutation now found in 10 percent of Europeans. Scientists speculate that the variant may have originally evolved as a protection against smallpox.
Paralleling the constant war against pathogens, human sperm may also be evolving at high speed, driven by the race to get to the egg before another man’s sperm. “It could be that cities create more sexual partners, which means fiercer competition among males,” Hawks says. Because sperm can fertilize an egg up to 24 hours after being ejaculated in the vagina, a woman who copulates with two or more partners in close succession is setting up the very conditions that pit one man’s sperm against another’s. Hawks infers that “sperm today is very different from sperm even 5,000 years ago.” Newly selected mutations in genes controlling sperm production show up in every ethnic group he and his team have studied; those genes may affect characteristics including abundance, motility, and viability. The selection for “super sperm,” Hawks says, provides further corroboration that our species is not particularly monogamous—a view widely shared by other anthropologists.
At the other end of the human life span, “genes that help us live longer get selected,” Hawks reports. This may seem counterintuitive, since evolutionary biologists long assumed that the elderly do not contribute to the gene pool and hence are invisible to natural selection. But as studies of the Hadza people of Tanzania and other groups suggest, children doted on by their grandmothers—receiving extra provisions and care—are more likely to survive and pass on their grandmothers’ genes for longevity. (Grandfathers were less involved with their grandchildren in the cultures studied, so the phenomenon is known as the “grandmother effect.”) Old men can also pass on their genes by mating with younger women.
As agriculture became established and started creating a reliable food supply, Hawks says, more men and women would have begun living into their forties and beyond—jump-starting the selection pressure for increased life span. In support of that claim, Moyzis is currently performing a genetic analysis of men and women in their nineties who are of European ancestry. He has traced many early-onset forms of cancer, heart disease, and Alzheimer’s to older human gene variants. “The idea is that people with more modern variants tend to have greater resistance to these chronic illnesses of old age and should be overrepresented in the age 90-plus population,” Moyzis says.
EVOLUTION AND THE BRAIN
Perhaps the most incendiary aspect of the fast-evolution research is evidence that the brain may be evolving just as quickly as the rest of the body. Some genes that appear to have been recently selected, Moyzis and his collaborators suggest, influence the function and development of the brain. Other fast-changing genes—roughly 100—are associated with neurotransmitters, including serotonin (a mood regulator), glutamate (involved in general arousal), and dopamine (which regulates attention). According to estimates, fully 40 percent of these neurotransmitter genes seem to have been selected in the past 50,000 years, with the majority emerging in just the past 10,000 years.
Addressing the hot-potato question—What might these changes signify?—Moyzis and Wang theorize that natural selection probably favored different abilities and dispositions as modern groups adapted to the increasingly complex social order ushered in by the first human settlements.
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When people in hunter-gatherer communities have a conflict, Moyzis reports, usually one of them will just walk away. “There is a great deal of fluidity in these societies,” he says, “so it’s easy to join another group.” But with the establishment of the first farming communities, we put down roots figuratively as well as literally. “You can’t just walk away,” Moyzis notes, a fact that would have created selection pressure to revise the mechanisms regulating aggression, such as the glutamate pathways involved in arousal. “When you domesticate animals, you tend to change genes in that system,” he says.
For decades theories about human evolution proliferated in the absence of hard evidence, but now human genetic data banks are large enough to put assumptions to the test.
The rise of settlements also promoted the breakdown of labor into specialized jobs. That, coupled with food surpluses from farming, led to systems of trade and the need to track the flow of resources, which in turn could have selected for individuals with specific cognitive strengths. “Mathematical ability is very important when it comes to keeping track of crops and bartering,” Wang says. “Certainly your working memory has to be better. You have to remember who owes you what.” The researchers point to China’s Mandarin system, a method of screening individuals for positions as tax collectors and other government administrators. For nearly 2,000 years, starting in A.D. 141, the sons of a broad cross section of Chinese society, including peasants and tradesmen, took the equivalent of standardized tests. “Those who did well on them would get a good job in the civil service and oftentimes had multiple wives, while the other sons remained in a rice field,” Moyzis says. “Probably for thousands of years in some cultures, certain kinds of intellectual ability may have been tied to reproductive success.”
Harpending and Cochran had previously—and controversially—marshaled similar evidence to explain why Ashkenazi Jews (those of northern European descent) are overrepresented among world chess masters, Nobel laureates, and those who score above 140 on IQ tests. In a 2005 article in the Journal of Biosocial Science, the scientists attributed Ashkenazis’ intellectual distinction to a religious and cultural environment that blocked them from working as farm laborers in central and northern Europe for almost a millennium, starting around A.D. 800. As a result, these Jews took jobs as moneylenders and financial administrators of estates. To make a profit, Harpending says, “they had to be good at evaluating properties and market risks, all the while dodging persecution.” Those who prospered in these mentally demanding and hostile environments, the researchers posit, would have left behind the most offspring. Critics note that the association between wealth and intelligence in this interpretation is circumstantial, however.
Stronger evidence that natural selection has continued to shape the brain in recent epochs comes from studies of DRD4, a mutation in a neurotransmitter receptor that Moyzis, Wang, and many others have linked to attention-deficit/hyperactivity disorder (ADHD). Children diagnosed with ADHD are twice as likely to carry the variant gene as those without the diagnosis. DRD4 makes a receptor in the brain less effective in bonding to dopamine, which might explain why Ritalin, which increases the amount of dopamine in the space between neurons, is often helpful in treating the problem.
Sequencing studies suggest that the DRD4 mutation arose 50,000 years ago, just as humans were spreading out of Africa. Its prevalence tends to increase the farther a population is from Africa, leading some investigators to dub it “the migratory gene.” At least one allele (or copy of the gene) is carried by 80 percent of some South American populations. In contrast, the allele is present in 40 percent of indigenous populations living farther north in the Americas and in just 20 percent of Europeans and Africans. Children with the mutation tend to be more restless than other youngsters and to score higher on tests of novelty-seeking and risk-taking, all traits that might have pushed those with the variant to explore new frontiers.
In the context of a modern classroom, it may be hard to understand why kids who appear distractible and disruptive might have a survival advantage. But research shows people with DRD4 do not differ in intelligence from national norms; if anything, they may on average be smarter. Moreover, behavior that may seem like a drawback today may not have been so in ancient environments. When broaching foreign terrain filled with unknown predators, “having the trait of focusing on multiple directions might have been a good thing,” Wang says. “People focused in one direction might get eaten.”
Humans in far-flungdomains encountered starkly different selective forces, adjusting to novel foods, predators, climates, and terrains.
NOT SO FAST
Despite all these clues that human evolution has continued and accelerated into modern times, many evolutionary biologists remain deeply skeptical of the claims. Their resistance comes from several directions.
Some independent experts caution that the tools for studying the human genome remain in their infancy, and reliably detecting genomic regions that have been actively selected is a challenging problem. The hypothesis that human evolution is accelerating “all rests on being able to identify recent areas of the genome under natural selection fairly accurately,” says human geneticist Jonathan Pritchard of the University of Chicago. And that, he warns, is tricky, involving many different assumptions (about population sizes on different continents, for instance) in the poorly documented period before recorded history.
Given such uncertainties, researchers are more likely to be persuaded that a mutation has been recently selected if they understand its function and if its rise in prevalence meshes well with known human migratory routes. Genetic variants fitting that description include those coding for lighter skin coloring, resistance to diseases such as malaria, and metabolic changes related to the digestion of novel foods. There is broad consensus that these represent genuine examples of recent adaptations.
Question marks surround many other recent genetic changes. We know almost nothing about most regions of the genome that have been identified as potential targets of natural selection, observes Sarah Tishkoff, a geneticist at the University of Pennsylvania School of Medicine. Until scientists understand more of the landscape of the human genome, she says, she will have a hard time believing that adaptive genetic differences between ethnic groups have mushroomed over the past 20,000 years. She is particularly wary of claims that selective pressures recently played a role in shaping different cognitive abilities and temperaments among ethnic groups. “We have no strong evidence of that,” Tishkoff says.
Francis Collins, who until last year headed the National Human Genome Research Institute at the National Institutes of Health, concurs. “This is not a place to idly speculate about possibilities,” he says. “When it comes to brain functioning, let’s be honest: That is a tinderbox of possible explosive reactions based upon a very unpretty history of discrimination and of demagogues using information that they claimed came from biology in order to put down some groups that they didn’t like.” Even when it comes to the ADHD connection, Collins is a skeptic. “I want to see DRD4 replicated by independent investigators on an independent sample of children,” he says.
In some circles, Moyzis says, to suggest that natural selection is acting on the human brain is tantamount to heresy—an incredible hypothesis that demands extraordinary proof. Harpending, Cochran, and their collaborators are mystified as to what it is that makes their theory so incredible. “I would turn that statement on its head,” Moyzis says. “The extraordinary claim is that evolution somehow stopped once we developed culture.” Cochran says, “You’re allowed to change, but only if it’s below the neck. Many people think the brain has to be immune to natural selection; if it isn’t, they don’t want to hear it.”
Harvard University evolutionary biologist Pardis Sebati defends that view. “The immune system and skin interact directly with the outside world,” she says. “They are our first line of defense.” Based on the current evidence, she concludes, sunlight and pathogens were among the strongest selective forces, and skin and the immune system underwent the most dramatic change; evolutionary pressures on the brain are not nearly as clear-cut. As Harvard geneticist David Altshuler wrote in response to one of Sebati’s articles, “It’s reassuring that differences between the races seem to be mostly skin deep.”
The “reassuring” quality of that belief makes those in the opposing camp wonder if some of the logic of skeptics is tinged with wishful thinking. Harvard’s Steven Pinker, the celebrated author of The Blank Slate and an expert on the evolution of language and the mind, addressed that point in an interview in New Scientist magazine: “People, including me, would rather believe that significant human biological evolution stopped between 50,000 and 100,000 years ago, before the races diverged, which would ensure that racial and ethnic groups are biologically equivalent.”
Many scientists apparently worry that proof of divergent brain evolution could be so racially polarizing that we, as a society, would almost be better off in the dark. Hawks responds that the best safeguard against bigotry is educating the public. He thinks we understand enough about human genetics to know that the notion of racial superiority is absurd. Intelligence, he argues, is not a single trait but a vast suite of abilities, and each ancestral environment may have favored a different set of talents. What is sorely needed, he says, is “an ecological framework” to interpret the results. “Groups are best adapted to their own environment, which eliminates the question of superiority.” Even he concedes, though, that communicating the nuances will be no easy task.
“Whatever we find,” Wang says, “it would never be justification for abandoning the egalitarian value that all individuals, regardless of their ethnicity, are deserving of the same rights and opportunities.” Moyzis expands on that line of reasoning, putting a sunny spin on the group’s findings. “It would be boring if all the races were fundamentally the same,” he argues. “It’s exciting to think that they bring different strengths and talents to the table. That is part of what makes melting-pot cultures like our own so invigorating and creative.”
Of course, in melting-pot cultures all kinds of ethnic groups intermingle freely, and the children who result literally meld our DNA together. Even if those groups were diverging, international travel is now causing the diversity to get lost in the genetic reshuffling. “That’s the ultimate irony,” Moyzis says. “By the time we finally settle this debate, we’ll all be such a mixture of genes that we won’t care.”
Joined: 02 May 2006 {Posts: 443 } Location: Île-de-France
Posted: Thu 12 Feb 2009 08:18 Post subject:
Quote:
Over the past 10,000 years, their data show, human evolution has occurred a hundred times more quickly than in any other period in our species’ history.
Quote:
“We are getting less alike, not merging into a single mixed humanity.”
Perhaps the second quote is correct with respect to the average over the last 10,000 years, but today I think this has all changed. The evolutionary pressures are greater in similarity world wide than they ever have been before.
1) I think human migration today is greater than any time in history.
2) Pathogens, arguably the greatest impetus for natural selection, are more global than any other time in history.
3) The human diet is more uniform than any time in history. For lunch I might eat a soup with noodles made from wheat grown in the US, palm oil grown in Indonesia, a banana grown anywhere in the moist tropics, and some sardines caught in the Atlantic off northwest Africa. Because of globalization, eating a similar meal anywhere in the world is common.
I guess they do recognize part of this at the end of the article:
Quote:
“That’s the ultimate irony,” Moyzis says. “By the time we finally settle this debate, we’ll all be such a mixture of genes that we won’t care.”
The article is badly edited. It repeatedly uses the word "races" to refer to populations adapted to local conditions. In the context of the article, there are tens of thousands of such divergent populations in every isolated valley, island, or region on the planet. To use "races" to denote such local variation (whether caused by adaptation or, more likely, drift) is misleading. To prefix the word with the definite article "the" (the article uses "the races") is grossly misleading. Such usage implies that the tens of thousands, or hundreds of thousands, of local populations around the globe (essentially extended families) are what U.S. popular culture calls "the races".
Joined: 07 Feb 2007 {Posts: 1829 } Location: Lookin DC Metro, Feelin Geneva
Posted: Thu 12 Feb 2009 21:13 Post subject:
fwsweet wrote:
The article is badly edited. It repeatedly uses the word "races" to refer to populations adapted to local conditions. In the context of the article, there are tens of thousands of such divergent populations in every isolated valley, island, or region on the planet. To use "races" to denote such local variation (whether caused by adaptation or, more likely, drift) is misleading. To prefix the word with the definite article "the" (the article uses "the races") is grossly misleading. Such usage implies that the tens of thousands, or hundreds of thousands, of local populations around the globe (essentially extended families) are what U.S. popular culture calls "the races".
Most of the references to "race" come from direct quotes from notable scientists.
Most of the references to "race" come from direct quotes from notable scientists.
Which does not make the statements any less assinine. Please read 3.6 Introduction to Science-As-Process and also read rule 3.1.3 before posting in this forum again. I find it hard to believe that you (or anyone) would actually make an appeal the The Voice of Authority in this website, especially in this forum.
Joined: 07 Oct 2007 {Posts: 248 } Location: United States
Posted: Fri 13 Feb 2009 03:24 Post subject:
This reminds me of when I first heard that humans stopped evolving. <---That seems unlikely to me, and even more unlikely is the possibility that everything besides the brain would've have kept adapting and evolving simply because of culture. <---Like what is said in the article, it seems that culture would have the opposite effect, and that it would induce at least subtle adaptations of the brain. It's almost as if some fervent believers of ceased brain evolution are wishful thinkers who are afraid of what it could mean at the "racial" or ethnic level.
This reminds me of when I first heard that humans stopped evolving. <---That seems unlikely to me, and even more unlikely is the possibility that everything besides the brain would've have kept adapting and evolving simply because of culture. <---Like what is said in the article, it seems that culture would have the opposite effect, and that it would induce at least subtle adaptations of the brain. It's almost as if some fervent believers of ceased brain evolution are wishful thinkers who are afraid of what it could mean at the "racial" or ethnic level.
I do not think there is any doubt that our species has evolved dramatically over the past 10 kya or so.
Malaria, for instance, only spread into humans when we began living in crowds (consequent to agriculture) 10 kya. And yet we have evolved at least four malaria-resistant adaptations since then (HbS, Duffy, and two different thalassemias).
Similarly, lactose tolerance is a mutation dating from herding, and the distinctive depigmentation (skin, eyes, hair) of northern Europeans dates from about 6 kya.
I am not sure about the brain, but there must be something behind the Flynn effect, even if only better nutrition and public health.
As MisterLawyer pointed out, however, the issue is not whether we have changed (through both drift and adaptation) in the past. Obviously we have. The issue is whether distinct local populations will continue to diverge from each other in the future. In the absence of time-travel anyone can play prophet. Personally, I agree with MisterLawyer. The age of the Boeing 747 is upon us.
Joined: 07 Feb 2007 {Posts: 1829 } Location: Lookin DC Metro, Feelin Geneva
Posted: Sat 14 Feb 2009 01:06 Post subject:
fwsweet wrote:
Dragon Horse wrote:
Most of the references to "race" come from direct quotes from notable scientists.
Which does not make the statements any less assinine. Please read 3.6 Introduction to Science-As-Process and also read rule 3.1.3 before posting in this forum again. I find it hard to believe that you (or anyone) would actually make an appeal the The Voice of Authority in this website, especially in this forum.
Here we go again...lets do this slowly.
"Most of the references to "race" come from direct quotes from notable scientists."
"Most of the references"
This refers to the references in the article.
"to race"
Meaning references about race.
"come from direct quotes from notable scientists"
meaning these are quotes, not all a result of editing, if the writer changed the quote that would be an editing issue. I said "notable scientists" as to say it was not "the writer" making these, but the "experts" being interviewed.
Claro?
Quote:
Which does not make the statements any less assinine.
Is this your scientific determination? I'm not disputing or making an argument simply attempting to learn. By the way, I left the misspelling of "assinine" as to avoid being accused of "misquoting".
Quote:
An appeal to authority or argument by authority is a type of argument in logic. It bases the truth value of an assertion on the authority, knowledge, expertise, or position of the source asserting it.
I did not appeal to authority, because I have not made an argument, nor have I supported an argument, or contradicted anything said in the article by you in regard to molecular biology, genetics, etc.
Quote:
3.1.3 Before posting an opinion on molecular anthropology or genetics, you must have read at least one introductory textbook on this topic and be able to name it.
I did not post an opinion on anything regarding the topic. You said that posting articles to inform or create discussion did not necessarily reflect the opinion of the poster. You do recall this conversation?
Still I have read:
"The Journey of Man: A Genetic Odyssey", by Spencer Wells, Ph.D.
I still have this book...
I have also read (years ago as part of a university class), "The History and Geography of Human Genes", by Luigi Luca Cavalli-Sforza, Ph.D.
The latter, is considered a pioneer in genetic anthropology...and the former was his understudy.
Does these count as acceptable texts?
Quote:
The position that you take in a dispute is called your thesis. Both parties in a dispute are expected to define their theses clearly, consistently, and falsifiably. State your thesis succinctly the moment that you enter a dispute.
I made no thesis (no position) and gave no opinion on the topics in this article whatsoever (or topic of this discussion section).
I did give a position, which is, the references to "race" were not just due to poor editing but actual statements made by the people interviewed, which would be correct editing because they are in quotes.
That is not required in this forum is it? At least that is what you told me. The only thing required is to post an appropriate for the section, has that changed?
Your opinion about their thoughts is your own, and I have not disputed it or any of their opinions or gave an opinion of my own unless you wish to argue the meaning of "editing"...
I believe my statement was clear and non-ambiguous and my explanation of which painfully base, as it appears that was necessary.
Last edited by Dragon Horse on Sat 14 Feb 2009 02:34; edited 2 times in total
Joined: 07 Feb 2007 {Posts: 1829 } Location: Lookin DC Metro, Feelin Geneva
Posted: Sat 14 Feb 2009 20:13 Post subject:
MisterLawyer wrote:
Quote:
Over the past 10,000 years, their data show, human evolution has occurred a hundred times more quickly than in any other period in our species’ history.
Quote:
“We are getting less alike, not merging into a single mixed humanity.”
Perhaps the second quote is correct with respect to the average over the last 10,000 years, but today I think this has all changed. The evolutionary pressures are greater in similarity world wide than they ever have been before.
1) I think human migration today is greater than any time in history.
2) Pathogens, arguably the greatest impetus for natural selection, are more global than any other time in history.
3) The human diet is more uniform than any time in history. For lunch I might eat a soup with noodles made from wheat grown in the US, palm oil grown in Indonesia, a banana grown anywhere in the moist tropics, and some sardines caught in the Atlantic off northwest Africa. Because of globalization, eating a similar meal anywhere in the world is common.
I guess they do recognize part of this at the end of the article:
Quote:
“That’s the ultimate irony,” Moyzis says. “By the time we finally settle this debate, we’ll all be such a mixture of genes that we won’t care.”
I think it depends.
Most people in the world still live in rural areas and are involved in agriculture and their lives have not changed remarkably for centuries.
That being said, what you stated is more true in Developed nations, especially ones with heterogeneous populations in the West.
Doing some basic math it is easy to see that it only takes a few mixes (reproduction of people from different continental groups) to introduce new genes into a given population that may become dominant (or fixed) over time.
I think short of some sci-fi like global disaster that isolates populations on opposite sides of the planet for centuries or better yet 1,000s of years, I don't see people speciating. That being said, it is obvious that gene flow is not equal at every location between every population globally and never has been, although there has been no such thing as "pure" isolation in human populations (that we know of).
So what you will see in the future is more people moving into urban areas (which has been the trend since the Industrial Revolution and has spread globally every since at different rates.
Those people will have more similar selection pressures than people did even 500 years ago, but their adaptation to those pressures does not need be identical.
I can give an example.
It might be that in the future, some populations that do not have lactose tolerance will see lactose tolerance become fixed in their popualation due to intermarriage (even what one would consider marginal with outside groups that have the gene), if this is beneficial to them.
At the same time we will also see co-vergent evolution.
Lactose tolerance has developed independently in East Africa, but does the same thing as the Western Eurasian variety.
Light skin in East Asians and Europeans comes from different genes, and manifest slightly different in appearance, but has the same effect...in increasing the production of vitamin D.
So I would expect to see both, which one has more of a effect...the centripetal force of gene flow or the divergent force of co-vergent evolution...I have no idea. I think that depends on the population we are discussing and what happens in the future. Some places on earth are going to grow much more related as time goes by, but not I'm not sure that will be true for every population.
Still I have read: "The Journey of Man: A Genetic Odyssey", by Spencer Wells, Ph.D. I still have this book... I have also read (years ago as part of a university class), "The History and Geography of Human Genes", by Luigi Luca Cavalli-Sforza, Ph.D. ... Does these count as acceptable texts?
No. Neither one is an introductory textbook. Wells is a popularization. Cavalli-Sforza is an advanced textbook. Nevertheless, I am suprised that you read the latter in a basic college course. What was the course? Do you recall how big the book was? How many volumes? or roughly how many pages?
Dragon Horse wrote:
That being said...the rules state: ... [long question about how to interpret rules paragraph 3.3.1] ... i asked the same question in the another thread...so you don't have to answer here...
Since you say that you posted this question twice, one copy should be deleted. Since you say that you prefer that your question not be answered in this thread, I have deleted it from this thread.
Joined: 07 Feb 2007 {Posts: 1829 } Location: Lookin DC Metro, Feelin Geneva
Posted: Mon 16 Feb 2009 00:16 Post subject:
fwsweet wrote:
Dragon Horse wrote:
Still I have read: "The Journey of Man: A Genetic Odyssey", by Spencer Wells, Ph.D. I still have this book... I have also read (years ago as part of a university class), "The History and Geography of Human Genes", by Luigi Luca Cavalli-Sforza, Ph.D. ... Does these count as acceptable texts?
No. Neither one is an introductory textbook. Wells is a popularization. Cavalli-Sforza is an advanced textbook. Nevertheless, I am suprised that you read the latter in a basic college course. What was the course? Do you recall how big the book was? How many volumes? or roughly how many pages?
Dragon Horse wrote:
That being said...the rules state: ... [long question about how to interpret rules paragraph 3.3.1] ... i asked the same question in the another thread...so you don't have to answer here...
Since you say that you posted this question twice, one copy should be deleted. Since you say that you prefer that your question not be answered in this thread, I have deleted it from this thread.
lol...
I read the Cavalli-Sforza in a grad elective class (Master's of Liberal Arts major); this was an anthropology class, don't remember names from 2003, but it had to be a 400 or 500 level class (not sure if that means anything to you as some universities do this differently). The assumption was likely that we had taken undergrad anthro classes up to at least 300 level, I did not, but they did not, but it was not my major so I was not blocked. I believe the title was something like "Human Geography and Culture" but don't quote me on that. I do know it was a "Special Topics" class.
As with most university classes, we only read selected sections for class, but later I read the entire book due to personal interest??? To my knowledge it is one book, there are no volumes and it is about 400 pgs, but as I said I don't own it anymore, so I can't give you the exact number. It was already an old book, but my professor felt certain sections served the purpose. I'm guessing it was not a first edition and I know it was the abridged paperback. I'm also not going to lie and say I understood the entire book, but I think I got a pretty good idea and that was the basis for further reading over the last 5-6 years.
I also own "Genes, Peoples, and Languages" by Luigi Luca Cavalli-Sforza, what you want to know about that, I can quote from the book and give you page number and paragraph as I own it. Then again I guess that was "popularized" as well.
I read the Cavalli-Sforza in a grad elective class... I also own Genes, Peoples, and Languages ...
Thank you. Knowing what you have read helps me to better answer your questions. Again, however, I must insist that you read an introductory college-level textbook on physical anthropology before posting any more opinions in this forum. I recommend a specific title elsewhere, but any introductory college-level textbook will suffice. Go to a college bookstore and buy whatever was assigned for physical anthropology 101. Then let me know the title and author. That way I can suggest specific pages where you can find answers to your questions.
Dragon Horse wrote:
What text have you read again?
You mean what do I recommend for you? Or are you asking what I read for my Ph.D. course work or dissertation research? If the former, I already named some titles in another post. If the latter, my dissertation bibliography alone has well over 400 titles, all of which I know very well indeed. The bookshelves that surround me as a write this hold well over 2,000 titles that I refer to frequently. Click here and then go to page 495, for a partial list.
Joined: 07 Feb 2007 {Posts: 1829 } Location: Lookin DC Metro, Feelin Geneva
Posted: Mon 16 Feb 2009 19:31 Post subject:
fwsweet wrote:
Dragon Horse wrote:
I read the Cavalli-Sforza in a grad elective class... I also own Genes, Peoples, and Languages ...
Thank you. Knowing what you have read helps me to better answer your questions. Again, however, I must insist that you read an introductory college-level textbook on physical anthropology before posting any more opinions in this forum. I recommend a specific title elsewhere, but any introductory college-level textbook will suffice. Go to a college bookstore and buy whatever was assigned for physical anthropology 101. Then let me know the title and author. That way I can suggest specific pages where you can find answers to your questions.
Dragon Horse wrote:
What text have you read again?
You mean what do I recommend for you? Or are you asking what I read for my Ph.D. course work or dissertation research? If the former, I already named some titles in another post. If the latter, my dissertation bibliography alone has well over 400 titles, all of which I know very well indeed. The bookshelves that surround me as a write this hold well over 2,000 titles that I refer to frequently. Click here and then go to page 495, for a partial list.
I'm referring to molecular biology/genetic anthropology/human geography. That was not the focus of your PhD research was it? I was referring to text on those subjects.
I will let you know what text I find for introductory physical anthro...
I'm referring to molecular biology/genetic anthropology/human geography. That was not the focus of your PhD research was it?
Yes it was, at least partly. My Ph.D. major is U.S. History. My minor is molecular anthropology. My dissertation, Legal History of the Color Line has two main sections. The first section, titled "America's Admixed Population" specifically addresses "molecular biology/genetic anthropology/human geography" as it relates to the genetics of the U.S. population. The second section deals with how U.S. courts "racially" classified Americans over the past 400 years. Specifically, how courts, past and present, have grappled with the mismatch between policy (a dichotomous color line) and genetic reality. Please feel free to buy a copy of the book or borrow it from a nearby library. The first 87 pages reference about 120 footnoted sources dealing with genetics, any of which might be useful to you, once you have a basic grounding in the topic and in scientific thinking (again: clarity of definition, falsifiability, replicability, and drawing conclusions from findings).
Look, Dragon Horse, you seem to have a problem accepting that I am an acknowledged authority in my field (the mismatch between genetic reality and U.S. legal policy), and that my field includes molecular anthropology. I have no problem with your skepticism. But, given your attitude, why do you come to my website to ask me questions about the topic? You would learn faster if you found someone in whom you had confidence and questioned them instead.
Joined: 07 Feb 2007 {Posts: 1829 } Location: Lookin DC Metro, Feelin Geneva
Posted: Mon 16 Feb 2009 20:45 Post subject:
fwsweet wrote:
Dragon Horse wrote:
I'm referring to molecular biology/genetic anthropology/human geography. That was not the focus of your PhD research was it?
Yes it was, at least partly. My Ph.D. major is U.S. History. My minor is molecular anthropology. My dissertation, Legal History of the Color Line has two main sections. The first section, titled "America's Admixed Population" specifically addresses "molecular biology/genetic anthropology/human geography" as it relates to the genetics of the U.S. population. The second section deals with how U.S. courts "racially" classified Americans over the past 400 years. Specifically, how courts, past and present, have grappled with the mismatch between policy (a dichotomous color line) and genetic reality. Please feel free to buy a copy of the book or borrow it from a nearby library. The first 87 pages reference about 120 footnoted sources dealing with genetics, any of which might be useful to you, once you have a basic grounding in the topic and in scientific thinking (again: clarity of definition, falsifiability, replicability, and drawing conclusions from findings).
Look, Dragon Horse, you seem to have a problem accepting that I am an acknowledged authority in my field (the mismatch between genetic reality and U.S. legal policy), and that my field includes molecular anthropology. I have no problem with your skepticism. But, given your attitude, why do you come to my website to ask me questions about the topic? You would learn faster if you found someone in whom you had confidence and questioned them instead.
I have no problem accepting anything.
Being that you are an authority you should be able to answer some base questions without referring me right away to a text. The questions were not that complex.
When I sat down with Walter Williams (I will assume you know who he is) about 2 years ago, who was gracious enough to meet me, and I asked him pointed questions about the utility of libertarianism as it relates to real world American economic application and the black community. He did not say "read this book"; well he did, but that was not his first response.
I was quite impressed with the fact he answered directly every single question that I had and then he said "for more detail about economic models of the theories I spoke of or the history of their application see these text", which he wrote out on a piece of paper for me. Most of the books were in his office. He offered to let me borrow one actually.
Now, this man is an economist, an "expert" in his field, a practicing professor, who is nationally known and widely quoted. That being said, he is not always correct (and he knows this).
I myself have a published papers at a Master's level (well co-authored). One on Vietnamese FDI (Foreign Direct Investment) Inflows in the Aftermath of the 1997 Asian Crisis and the other on a model developed to analyze Single Party State FDI Acquisition, where China and Vietnam were used as case studies to explain the utility of the model.
Still, I am no economist, my work was more from a public policy and political perspective, using levels of FDI as a yardstick to successful policy.
I learned that "citing text" to support an argument does not mean you are an expert on the material you are citing, not even close, not necessarily. If your data is not quantitative from original research or metadata it often comes down to (even in published peer reviewed work) to be someone making a statement and supporting it with 3 or 4 people who said the same thing, at least in the field I studied...not implying this about your work, I don't know intimately...
In any case, back to Professor Williams, I do not consider myself the equal of Walter Williams when it comes to pure economics although I have more working knowledge of certain sectors of specific types of economies than him, his knowledge of the inner-workings of the American economy and it's history make mine look quite base.
That being said he met with me due to an e-mail I wrote him concerning a book he wrote, "More Liberty Means Less Government".
He was not arrogant and he did not attempt to debase. He answered my specific questions. I told him I had some more and asked if he had office hours where I could meet him to discuss for just 1/2 hour. To my surprise, he agreed. We talked for 1.5 hours.
I have no clue why it is you can't be even half as gracious as he.
In about 3 hours I will ask you one pointed question in regard to what I wrote (again) based off of the pgs. you referred me to "Genes, Peoples, and Languages". I will quote specific passages and give you pg. numbers for them.
Now, I know Professor Williams will give pointed answers to whatever questions and not cop out.
I have no clue why it is you can't be even half as gracious as he.
Two possibilities. (1) Because you already knew enough about his field to ask questions without erroneous built-in assumptions and to then understand his answers. (2) Because I am naturally ungracious.
Again, if you find me ungracious, arrogant, and debasing, why come to me? There are other experts out there with whom you would probably be more comfortable.
I have read: "The Journey of Man: A Genetic Odyssey", by Spencer Wells, Ph.D.
Good popularization. Very basic, but I recommend it also. My only complaint about Wells is that he does not mention Toba.
The Toba supervolcano erupted 74,000 years ago and covered the Indian subcontinent in 18 feet of ash, wiping out all life (plant and animal) in the region.
Wells mentions the timing discontinuity between there being evidence of people in Australia 60 KYA, but no evidence before 40 KYA of people along the coast of India. He suggests that the earlier evidence of people along the Indian coast is submerged. He neglects to point out that any evidence of humans on the way to Australia would be buried under the 18 feet of ash that is still there. In addition, we can see a DNA discontinuity across India, traces of the cataclysmic event.
'
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Then again I guess that was "popularized" as well.
