J Scott Hill's List: ethnicity and race

• The Dawes Act of 1887, which allotted tribal lands in severalty to individuals, was seen as a way to create individual homesteads for Native Americans. Land allotments were made in exchange for Native Americans' becoming US citizens and giving up some forms of tribal self-government and institutions. It resulted in the transfer of an estimated total of 93 million acres (6,100 km²) from Native American control. Most was sold to individuals. The Indian Citizenship Act of 1924 was also part of Americanization policy.

• With officials believing in the virtue of Christianity, the United States Government worked to convert American Indians to Christianity and suppress the practice of the Native religions (spiritual leaders had been associated with leading uprisings.) The goal of the United States Government was to get Native Americans to assimilate to their culture. Some called this "making apples", as the Indians would still appear 'red' on the outside, but would be made 'white' on the inside.^[35]

   

  Even in the 20th century, "spiritual leaders ran the risk of jail sentences of up to 30 years for simply practicing their rituals".^[36] The law did not change until the passage of the American Indian Religious Freedom Act (AIRFA) of 1978, although the government had stopped prosecuting Native American spiritual leaders.^[35]
• By 1923 in the Northwest, most Indian schools had closed and Indian students were attending public schools. States took on increasing responsibility for their education.^[37] Other studies suggest attendance in some Indian boarding schools grew in areas of the United States throughout the first half of the 20th century, doubling from 1900 to the 1960s.^[38] Enrollment reached its highest point in the 1970s. In 1973, 60,000 American Indian children were estimated to have been enrolled in an Indian boarding school.^[39][40]
• Pratt professed "assimilation through total immersion." Because he had seen men educated at schools like Hampton Institute become educated and assimilated, he believed the principles could be extended to Indian children. Immersing them in the larger culture would help them adapt. In addition to reading, writing, and arithmetic, the Carlisle curriculum was modeled on the many industrial schools: it constituted vocational training for boys and domestic science for girls, in expectation of their opportunities on the reservations, including chores around the school and producing goods for market. In the summer, students were assigned to local farms and townspeople for boarding and to continue their immersion. They also provided labor at low cost, at a time when many children earned pay for their families.

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• Even with the human genome in hand, geneticists are split about how to deal with issues of race, genetics and medicine.
• Some favor using genetic markers to sort humans into groups based on ancestral origin - groups that may show meaningful health differences. Others argue that genetic variations across the human species are too gradual to support such divisions and that any categorisation based on genetic differences is arbitrary.

• 1. All races are created equal

                        

  No genetic data has ever shown that one group of people is inherently superior to another. Equality is a moral value central to the idea of human rights; discrimination against any group should never be tolerated.

• 2. An Argentinian and an Australian are more likely to have differences in their DNA than two Argentinians

                      

  Groups of human beings have moved around throughout history. Those that share the same culture, language or location tend to have different genetic variations than other groups. This is becoming less true, though, as populations mix.

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• By creating genetic "clocks," scientists can make fairly careful guesses about when particular groups became the color they are today. And with the help of paleontologists and anthropologists, scientists can go further: They can wind the clock back and see what colors these populations were going back tens of thousands of years, says Jablonski.
  
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  She says that for many families on the planet, if we look back only 100 or 200 generations (that's as few as 2,500 years), "almost all of us were in a different place and we had a different color."

• The chart to the left illustrates the two primary biochemical dynamics which serve as oppositional selective forces upon the color of human skin; which itself is just a reflection of melanin density and size. Though popular reports focus on the increased cancer rates of light skinned individuals, it is important to remember that cancers often occur late in life and so their reproductive impact is diminished. Nina Jablonski has put forward a more reproductively salient selective pressure: the interference with folic acid synthesis which occurs when excessive UV radiation penetrates deep into the dermis. The end result of this is reduced folate levels, which in pregnant females often causes neural tube abnormalities. Any impact on pregnancy success is an extremely powerful selective force. In this model the dark skin of humans naturally arose because women who were darker skinned carried more normal fetuses to term than those who were light skinned. In dark skinned populations the MC1R locus is extremely conserved, suggesting powerful selective constraints which prevent sequence variation.
• In Jablonski’s model this is comprehensible insofar as one moves north the the UV radiation drops. This means that melanin pigement concentrations need not be as dense to protect the folic acid synthesis pathway from degradation. And, the reduced density of melanin maybe necessary for vitamin D levels to be maintained due to the essential role of radiation in catalyzing its production.
• Recently work in genomics also suggests genes implicated in various metabolic functions have been under powerful selection over the past 10,000 years as the agricultural lifestyle has spread. The deleterious consequences of switching many non-agricultural populations to the starch rich diet are well known (obesity, diabetes, etc.). Selection happens, and it seems likely that a genetic revolution was ushered in by the radically altered nutritional universe of the farmer. Which brings me to Europeans and why they might be so light.
• But with the spread of agriculture Vitamin D disappeared from the diets of northern European peoples and so only by reducing their melanin levels could they produce sufficient amounts of this nutrient to keep at bay the deleterious consequences of deficiencies. This explains why the Sami, who never adopted agriculture, remained darker.
• In 2005 a gene, SLC24A5, was implicated in explaining a large proportion (25-38%) of the between population difference in skin color for Europeans and Africans. It seems that on this locus the two populations were disjoint, they exhibited no substantial overlap. In European it seems that 6 to 10 thousand years ago a new variant arose which subsequently swept to fixation. In the model above it seems likely that the mutation was just there at “the right place and right time.” Interestingly in East Asians SLC24A5 exhibits the same sequence as it does in Africans. But, it seems that other loci are responsible for the lightening of the skin of East Asians recently as well, though not to the same extent as Europeans. The reason for this is likely the fact that temperate East Asia as at a far lower latitude than Europe.
• Though Sweet doesn’t say it in so many words he is basically suggesting that gain of function mutations are rare relative to loss of function. There are two parameters which might explain the relative lightness or darkness (and overall homogeneity) of New World populations. First, settlement was relatively recent, so there hasn’t been enough time for evolution to work. Of course the copious evidence of recent human evolution suggests that this isn’t really a major issue. Rather, the bigger problem was likely that extant genetic variation was reduced by a population bottleneck. Over time this variation would be replenished by mutation, but this is a slow process. Tropical populations of the New World are not only lighter than one would expect, they also display a far stockier and “northern” build than they should if form followed from function. This suggests evolutionary lag on many characteristics due to the low genetic diversity combined with the particular time frame over which evolution could occur (but even here, do note that there is a skin color gradation from the tropics to the temperate zones in the New World among indigenous peoples).

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• The first of those sites to be studied contains the gene known as EDAR. Africans and Europeans carry the standard version of the gene, but in most East Asians, one of the DNA units has mutated.

• The finding that the gene has so many effects raises the question of which one was the dominant trigger for natural selection.

   Dr. Sabeti said the extra sweat glands could have been the feature favored by natural selection, with all the other effects being dragged along in its train.

   “We’re the only mammals to have changed their entire hair pattern. So the changes in teeth, hair and breasts — it’s very possible they are the passengers and thermoregulation is the key,” she said, referring to the role of sweat glands in cooling the body.
• But Joshua Akey, a geneticist at the University of Washington in Seattle, said he thought the more likely cause of the gene’s spread among East Asians was sexual selection. Thick hair and small breasts are visible sexual signals which, if preferred by men, could quickly become more common as the carriers had more children. The genes underlying conspicuous traits, like blue eyes and blond hair in Europeans, have very strong signals of selection, Dr. Akey said, and the sexually visible effects of EDAR are likely to have been stronger drivers of natural selection than sweat glands.

• A series of selections on different traits thus made the variant version so common among East Asians. About 93 percent of Han Chinese carry the variant, as do about 70 percent of people in Japan and Thailand, and 60 to 90 percent of American Indians, a population descended from East Asians.

   The Broad team is studying EDAR as part of a larger plan to identify all the genetic variants responsible for recent human evolution

• A team led by Dr. Sabeti and Sharon R. Grossman of the Broad Institute has now refined the usual scanning methods and identified 412 sites on the genome that have been under selection. Each site is small enough that it contains at most a single gene.

   Each race has a different set of selected regions, reflecting the fact that the human population had dispersed from its African homeland and faced different challenges that led to genetic adaptation on each continent. About 140 of the sites affected by natural selection are in Europeans, 140 in East Asians and 132 in Africans, the authors report in another article published Thursday in Cell.

   Inserting some of the other selected genes into mice might help explain why they were favored, and point to critical turning points in recent human evolution, Dr. Sabeti said.

   In the case of EDAR, putting the gene into mice has only magnified the mystery of why it was selected. But the researchers are not discouraged. “A reflection of good science is that a step forward opens up a lot more questions,” Dr. Akey said.

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