You'll see in your schedule for June 27/28:
Due: RA #2, WW Part 5 (Intro, Chapters TBA).
With regard to WW Part 5, please read the Intro and ONE of the chapters from Part 5. You may choose whichever chapter you find most interesting. In addition, please read the chapter excerpted from Discovering the Global Past which was (last night) or will be (tonight) handed out in class.
PA
Tuesday, June 21, 2011
Friday, June 17, 2011
Activity / Assignment for July 4 / 5
The activity portion of the following assignment will compensate for the week of class we miss due to the July 4 holiday. The resulting written portion will serve as your Research Paper or Oral History Project. The written portion is due when we meet the week of July 11/12. You will also make a 5-10 minute presentation of your work during our final class session on July 18/19. Your presentation may be pre-recorded and posted to your blog in a format that can be viewed in class over the internet.
Please complete ONE of the following assignments. (Just one.)
EITHER
Oral History / Research Project
Conduct an Oral History interview of a person who lived through a significant historical event, era or situation. Develop some questions prior to your interview. What do you want to know? What can you find out before you meet for the interview? What can you find out only by experiencing the person’s face-to-face presence? During the interview, attempt to find answers to those questions. Write a paper that attempts to answer one of your questions using the transcript of your interview as a primary source. 4-8 pages
OR
Field Trip / Research Project
Plan a trip to a museum, exhibit, historical place, etc. Examples of appropriate places to visit are noted below. Develop some questions prior to your visit. What do you want to know? What can you find out before you get there? What can you only find out by experiencing the visit in person? During your visit, attempt to find answers to those questions. Do additional research as needed afterward to clarify your results. Write a paper that analyzes the topic from the perspective of one of your questions. 4-8 pages.
• Angel Island Immigration Station
• Chumash Painted Caves & Natural History Museum exhibit, Santa Barbara
• Hearst Museum, Berkeley (Ishi / Native California Cultures exhibit)
• Rosicrucian Museum, San Jose
• Asian Art Museum, San Francisco (choose specific exhibit)
Please complete ONE of the following assignments. (Just one.)
EITHER
Oral History / Research Project
Conduct an Oral History interview of a person who lived through a significant historical event, era or situation. Develop some questions prior to your interview. What do you want to know? What can you find out before you meet for the interview? What can you find out only by experiencing the person’s face-to-face presence? During the interview, attempt to find answers to those questions. Write a paper that attempts to answer one of your questions using the transcript of your interview as a primary source. 4-8 pages
OR
Field Trip / Research Project
Plan a trip to a museum, exhibit, historical place, etc. Examples of appropriate places to visit are noted below. Develop some questions prior to your visit. What do you want to know? What can you find out before you get there? What can you only find out by experiencing the visit in person? During your visit, attempt to find answers to those questions. Do additional research as needed afterward to clarify your results. Write a paper that analyzes the topic from the perspective of one of your questions. 4-8 pages.
• Angel Island Immigration Station
• Chumash Painted Caves & Natural History Museum exhibit, Santa Barbara
• Hearst Museum, Berkeley (Ishi / Native California Cultures exhibit)
• Rosicrucian Museum, San Jose
• Asian Art Museum, San Francisco (choose specific exhibit)
Excerpt from the Analects of Confucius
The Superior Man (chün-tzu)
from The Analects of Confucius
XX.3: The Master said, "Without recognizing the ordinances of Heaven, it is impossible to be a superior man (chün tzu)."
XV.17: The Master said, "The superior man in everything considers righteousness to be essential. He performs it according to the rules of propriety (li ). He brings it forth in humility. He completes it with sincerity. This is indeed a superior man."
XV.31: The Master said, "The object of the superior man is truth, not food. . . . The superior man is anxious lest he should not get truth; he is not anxious lest poverty should come upon him."
IV.16: The Master said, "The mind of the superior man is conversant with virtue; the mind of the base man is conversant with gain."
IV.5: The Master said, "Riches and honors are what men desire. If they cannot be obtained in the proper way, they should not be held. Poverty and baseness are what men dislike. If they cannot be avoided in the proper way, they should not be avoided. . . . The superior man does not, even for the space of a single meal, act contrary to virtue. In moments of haste, he cleaves to it. In seasons of danger, he cleaves to it."
XV.20: The Master said, "What the superior man seeks, is in himself. What the mean man seeks, is in others."
XII.4: Ssu-ma Niu asked about the superior man. The Master said, "The superior man has neither anxiety nor fear." "Being without anxiety or fear!" said Ssu-ma, "does this constitute what we call the superior man?" The Master said, "When internal examination discovers nothing wrong, what is there to be anxious about, what is there to fear?"
XIV.24: The Master said, "The progress of the superior man is upwards; the progress of the mean man is downwards."
XVI.8: Confucius said, "There are three things of which the superior man stand in awe. He stands in awe of the ordinances of Heaven. He stands in awe of great men. He stands in awe of the words of the sages. The mean man does not know the ordinances of Heaven, and consequently does not stand in awe of them. He is disrespectful to great men. He makes sport of the words of the sages."
XIV.29: The Master said, "The superior man is modest in his speech, but exceeds in his actions."
XV.18: The Master said, "The superior man is distressed by his want of ability. He is not distressed by men not knowing of him."
XV.21: The Master said, "The superior man is dignified, but does not wrangle. He is sociable, but not partisan."
XVII.24: Tzu-kung asked, "Has the superior man his hatreds also?" The Master said, "He has his hatreds. He hates those who proclaim the evil of others. He hates the man who, being in a low station, slanders his superiors. He hates those who have valor merely, and are unobservant of propriety (li ). He hates those who are forward and determined, and, at the same time, of contracted understanding."
XVI.10: Confucius said, "The superior man has nine things which are subjects with him of thoughtful consideration. In regard to the use of his eyes, he is anxious to see clearly. In regard to the use of his ears, he is anxious to hear distinctly. In regard to his countenance, he is anxious that it should be benign. In regard to his speech, he is anxious that it should be sincere. In regard to his doing of business, he is anxious that it should be reverently careful. In regard to what he doubts about, he is anxious to question others. When he is angry, he thinks of the difficulties his anger may involve him in. When he sees gain to be got, he thinks of righteousness."
XIX.9: Tzu-hsia said, "The superior man undergoes three changes. Looked at from a distance, he appears stern; when approached, he is mild; when he is heard to speak, his language is firm and decided."
XV.36: The superior man is correctly firm, and not merely firm.
from The Analects of Confucius
XX.3: The Master said, "Without recognizing the ordinances of Heaven, it is impossible to be a superior man (chün tzu)."
XV.17: The Master said, "The superior man in everything considers righteousness to be essential. He performs it according to the rules of propriety (li ). He brings it forth in humility. He completes it with sincerity. This is indeed a superior man."
XV.31: The Master said, "The object of the superior man is truth, not food. . . . The superior man is anxious lest he should not get truth; he is not anxious lest poverty should come upon him."
IV.16: The Master said, "The mind of the superior man is conversant with virtue; the mind of the base man is conversant with gain."
IV.5: The Master said, "Riches and honors are what men desire. If they cannot be obtained in the proper way, they should not be held. Poverty and baseness are what men dislike. If they cannot be avoided in the proper way, they should not be avoided. . . . The superior man does not, even for the space of a single meal, act contrary to virtue. In moments of haste, he cleaves to it. In seasons of danger, he cleaves to it."
XV.20: The Master said, "What the superior man seeks, is in himself. What the mean man seeks, is in others."
XII.4: Ssu-ma Niu asked about the superior man. The Master said, "The superior man has neither anxiety nor fear." "Being without anxiety or fear!" said Ssu-ma, "does this constitute what we call the superior man?" The Master said, "When internal examination discovers nothing wrong, what is there to be anxious about, what is there to fear?"
XIV.24: The Master said, "The progress of the superior man is upwards; the progress of the mean man is downwards."
XVI.8: Confucius said, "There are three things of which the superior man stand in awe. He stands in awe of the ordinances of Heaven. He stands in awe of great men. He stands in awe of the words of the sages. The mean man does not know the ordinances of Heaven, and consequently does not stand in awe of them. He is disrespectful to great men. He makes sport of the words of the sages."
XIV.29: The Master said, "The superior man is modest in his speech, but exceeds in his actions."
XV.18: The Master said, "The superior man is distressed by his want of ability. He is not distressed by men not knowing of him."
XV.21: The Master said, "The superior man is dignified, but does not wrangle. He is sociable, but not partisan."
XVII.24: Tzu-kung asked, "Has the superior man his hatreds also?" The Master said, "He has his hatreds. He hates those who proclaim the evil of others. He hates the man who, being in a low station, slanders his superiors. He hates those who have valor merely, and are unobservant of propriety (li ). He hates those who are forward and determined, and, at the same time, of contracted understanding."
XVI.10: Confucius said, "The superior man has nine things which are subjects with him of thoughtful consideration. In regard to the use of his eyes, he is anxious to see clearly. In regard to the use of his ears, he is anxious to hear distinctly. In regard to his countenance, he is anxious that it should be benign. In regard to his speech, he is anxious that it should be sincere. In regard to his doing of business, he is anxious that it should be reverently careful. In regard to what he doubts about, he is anxious to question others. When he is angry, he thinks of the difficulties his anger may involve him in. When he sees gain to be got, he thinks of righteousness."
XIX.9: Tzu-hsia said, "The superior man undergoes three changes. Looked at from a distance, he appears stern; when approached, he is mild; when he is heard to speak, his language is firm and decided."
XV.36: The superior man is correctly firm, and not merely firm.
Quiz 3 Study Guide
Quiz 3 Topics for Study
Topic 1 will definitely be on the quiz.
Please see notes from a classmate to find out which topics were eliminated as possible quiz questions during class.
1) Please draw our world historical timeline as we have constructed it so far this semester (up to but not including the Modern Era). You should have 5 major milestones listed on your timeline, along with their approximate dates / date ranges, and a sentence or two explaining what characterizes each one.
2) Strayer causes a significant and useful shift in his reader’s perspective by using the term “gatherer-hunter” instead of the traditional “hunter-gatherer.”
3) Through the character of Enkidu, the ancient Mesopotamians have communicated what it meant to them to be civilized human beings.
4) By attempting to control free communications over the internet, China has increased its isolation relative to other countries along these “cyber roads.” In continuing along this path, China is repeating one of the mistakes of her past.
5) “We think that way because it’s our way of thinking” (student blog, Spring 2010). Discuss. How can the study of Paleolithic societies hep us re-evaluate our contemporary assumptions about man’s role on the planet?
6) What were the Confucian notions of “the Superior Man” and the “Mandate of Heaven”? In what ways did these ideas shape the Chinese state as it evolved after approximately 500 BC? Do they still guide Chinese thinking and behavior today?
7) How did Buddhism challenge the caste system in India?
8) How did “Christendom” evolve during the Classical Era, and why is it of historical significance even to people who do not profess the Christian faith?
9) How did Islam evolve during the Classical Era, and why is it of historical significance even to people who do not profess the Muslim faith?
10) The Mongols got a bad rap. In fact, they made significant long-term contributions to the evolution of the Eurasian world.
11) 1492 was a Very Bad Year, both for what ended in Spain and for what began there.
Topic 1 will definitely be on the quiz.
Please see notes from a classmate to find out which topics were eliminated as possible quiz questions during class.
1) Please draw our world historical timeline as we have constructed it so far this semester (up to but not including the Modern Era). You should have 5 major milestones listed on your timeline, along with their approximate dates / date ranges, and a sentence or two explaining what characterizes each one.
2) Strayer causes a significant and useful shift in his reader’s perspective by using the term “gatherer-hunter” instead of the traditional “hunter-gatherer.”
3) Through the character of Enkidu, the ancient Mesopotamians have communicated what it meant to them to be civilized human beings.
4) By attempting to control free communications over the internet, China has increased its isolation relative to other countries along these “cyber roads.” In continuing along this path, China is repeating one of the mistakes of her past.
5) “We think that way because it’s our way of thinking” (student blog, Spring 2010). Discuss. How can the study of Paleolithic societies hep us re-evaluate our contemporary assumptions about man’s role on the planet?
6) What were the Confucian notions of “the Superior Man” and the “Mandate of Heaven”? In what ways did these ideas shape the Chinese state as it evolved after approximately 500 BC? Do they still guide Chinese thinking and behavior today?
7) How did Buddhism challenge the caste system in India?
8) How did “Christendom” evolve during the Classical Era, and why is it of historical significance even to people who do not profess the Christian faith?
9) How did Islam evolve during the Classical Era, and why is it of historical significance even to people who do not profess the Muslim faith?
10) The Mongols got a bad rap. In fact, they made significant long-term contributions to the evolution of the Eurasian world.
11) 1492 was a Very Bad Year, both for what ended in Spain and for what began there.
Friday, June 10, 2011
A discussion of Don's question about variations in skin color...
http://humanorigins.si.edu/evidence/genetics/skin-color
Human Skin Color Variation
The DNA of all people around the world contains a record of how living populations are related to one another, and how far back those genetic relationships go. Understanding the spread of modern human populations relies on the identification of genetic markers, which are rare mutations to DNA that are passed on through generations. Different populations carry distinct markers. Once markers have been identified, they can be traced back in time to their origin – the most recent common ancestor of everyone who carries the marker. Following these markers through the generations reveals a genetic tree of many diverse branches, each of which may be followed back to where they all join – a common African root.
The mitochondria inside each cell are the power stations of the body; they generate the energy necessary for cellular organisms to live and function. Mitochondria have their own DNA, abbreviated mtDNA, distinct from the DNA inside the nucleus of each cell. mtDNA is the female equivalent of a surname: it passes down from mother to offspring in every generation, and the more female offspring a mother and her female descendants produce, the more common her mtDNA type will become. But surnames mutate across many generations, and so mtDNA types have changed over the millennia. A natural mutation modifying the mtDNA in the reproductive cells of one woman will from then on characterize her descendants. These two fundamentals – inheritance along the mother line and occasional mutation – allow geneticists to reconstruct ancient genetic prehistory from the variations in mtDNA types that occur today around the world.
Population genetics often use haplogroups, which are branches on the tree of early human migrations and genetic evolution. They are defined by genetic mutations or "markers" found in molecular testing of chromosomes and mtDNA. These markers link the members of a haplogroup back to the marker's first appearance in the group's most recent common ancestor. Haplogroups often have a geographic relation.
A synthesis of mtDNA studies concluded that an early exodus out of Africa, evidenced by the remains at Skhul and Qafzeh by 135,000 to 100,000 years ago, has not left any descendants in today’s Eurasian mtDNA pool. By contrast, the successful exodus of women carrying M and N mtDNA, ancestral to all non-African mtDNA today, at around 60,000 years ago may coincide with the unprecedented low sea-levels at that time, probably opening a route across the Red Sea to Yemen. Another study of the a subset of the human mtDNA sequence yielded similar results, finding that the most recent common ancestor of all the Eurasian, American, Australian, Papua New Guinean, and African lineages dates to between 73,000 and 57,000 years ago, while the average age of convergence, or coalescence time, of the three basic non-African founding haplogroups M, N, and R is 45,000 years ago.
This information has enabled scientists to develop intriguing hypotheses about when dispersals took place to different regions of the world. These hypotheses can be tested with further studies of genetics and fossils.
Modern Human Diversity - Skin Color
Why do people from different parts of the world have different colored skin? Why do people from the tropics generally have darker skin color that those who live in colder climates? Variations in human skin color are adaptive traits that correlate closely with geography and the sun’s ultraviolet (UV) radiation.
As early humans moved into hot, open environments in search of food and water, one big challenge was keeping cool. The adaptation that was favored involved an increase in the number of sweat glands on the skin while at the same time reducing the amount of body hair. With less hair, perspiration could evaporate more easily and cool the body more efficiently. But this less-hairy skin was a problem because it was exposed to a very strong sun, especially in lands near the equator. Since strong sun exposure damages the body, the solution was to evolve skin that was permanently dark so as to protect against the sun’s more damaging rays.
Melanin, the skin's brown pigment, is a natural sunscreen that protects tropical peoples from the many harmful effects of ultraviolet (UV) rays. UV rays can, for example, strip away folic acid, a nutrient essential to the development of healthy fetuses. Yet when a certain amount of UV rays penetrates the skin, it helps the human body use vitamin D to absorb the calcium necessary for strong bones. This delicate balancing act explains why the peoples that migrated to colder geographic zones with less sunlight developed lighter skin color. As people moved to areas farther from the equator with lower UV levels, natural selection favored lighter skin which allowed UV rays to penetrate and produce essential vitamin D. The darker skin of peoples who lived closer to the equator was important in preventing folate deficiency. Measures of skin reflectance, a way to quantify skin color by measuring the amount of light it reflects, in people around the world support this idea. While UV rays can cause skin cancer, because skin cancer usually affects people after they have had children, it likely had little effect on the evolution of skin color because evolution favors changes that improve reproductive success.
There is also a third factor which affects skin color: coastal peoples who eat diets rich in seafood enjoy this alternate source of vitamin D. That means that some Arctic peoples, such as native peoples of Alaska and Canada, can afford to remain dark-skinned even in low UV areas. In the summer they get high levels of UV rays reflected from the surface of snow and ice, and their dark skin protects them from this reflected light.
Modern Human Diversity - Genetics
People today look remarkably diverse on the outside. But how much of this diversity is genetically encoded? How deep are these differences between human groups? First, compared with many other mammalian species, humans are genetically far less diverse – a counterintuitive finding, given our large population and worldwide distribution. For example, the subspecies of the chimpanzee that lives just in central Africa, Pan troglodytes troglodytes, has higher levels of diversity than do humans globally, and the genetic differentiation between the western (P. t. verus) and central (P. t. troglodytes) subspecies of chimpanzees is much greater than that between human populations.
Early studies of human diversity showed that most genetic diversity was found between individuals rather than between populations or continents and that variation in human diversity is best described by geographic gradients, or clines. A wide-ranging study published in 2004 found that 87.6% percent of the total modern human genetic diversity is accounted for by the differences between individuals, and only 9.2% between continents. In general, 5%–15% of genetic variation occurs between large groups living on different continents, with the remaining majority of the variation occurring within such groups (Lewontin 1972; Jorde et al. 2000a; Hinds et al. 2005). These results show that when individuals are sampled from around the globe, the pattern seen is not a matter of discrete clusters – but rather gradients in genetic variation (gradual geographic variations in allele frequencies) that extend over the entire world. Therefore, there is no reason to assume that major genetic discontinuities exist between peoples on different continents or "races." The authors of the 2004 study say that they ‘see no reason to assume that "races" represent any units of relevance for understanding human genetic history. An exception may be genes where different selection regimes have acted in different geographical regions. However, even in those cases, the genetic discontinuities seen are generally not "racial" or continental in nature but depend on historical and cultural factors that are more local in nature’ (Serre and Pääbo 2004: 1683-1684).
Web Resources
http://www.understandingrace.org/humvar/
http://www.indiana.edu/~arch/saa/matrix/aea/aea_syl.html
https://www3.nationalgeographic.com/genographic/index.html
Bibliography
Cann, R., Stoneking, M., Wilson, A., 1987. Mitochondrial DNA and human evolution. Nature 352, 31-36.
Cavalli-Sforza, L.L., Menozzi, P., Piazza, A., 1994. The History and Geography of Human Genes. Princeton University Press, Princeton, NJ.
Ebersberger, I., Metzler, D., Schwarz, C., Pääbo, S., 2002. Genomewide comparison of DNA sequences between humans and chimpanzees. American Journal of Human Genetics 70, 1490–1497.
Fischer, A., Wiebe, V., Pääbo, S., Przeworski, M., 2004. Evidence for a complex demographic history of chimpanzees. Molecular Biology and Evolution 21, 799-808.
Forster, P., 2004. Ice Ages and the mitochondrial DNA chronology of human dispersals: a review. Philosophical Transactions of the Royal Society of London B 359, 255–264.
Gonder, M.K., Mortensen, H.M., Reed, F.A., de Sousa, A., Tishkoff, S.A., 2007. Whole-mtDNA genome sequence analysis of ancient African lineages. Molecular Biology and Evolution 24, 757–768.
Hinds D.A., Stuve L.L., Nilsen G.B., Halperin E., Eskin E., Ballinger D.G., Frazer K.A., Cox D.R., 2005. Whole-genome patterns of common DNA variation in three human populations. Science 307, 1072–1079.
Ingman, M., Kaessmann, H., Pääbo, S., Gyllensten, U., 2000. Mitochondrial genome variation and the origin of modern humans. Nature 408, 708–713.
Ingman, M., Gyllensten, U., 2001. Analysis of the complete human mtDNA genome: methodology and inferences for human evolution. Journal of Heredity 2001:92, 454-461.
Jorde, L.B., Watkins, W.S., Bamshad, M.J., Dixon, M.E., Ricker, C.E., Seielstad, M.T., Batzer, M.A., 2000. The distribution of human genetic diversity: a comparison of mitochondrial, autosomal, and Y-chromosome data. American Journal of Human Genetics 66, 979–988.
Kaessmann, H., Heissig, F., von Haeseler, A., Pääbo, S., 1999. DNA sequence variation in a non-coding region of low recombination on the human X chromosome. Nature Genetics 22, 78-81.
Kaessmann, H., Wiebe, V., Weiss, G., Pääbo, S., 2001. Great ape DNA sequences reveal a reduced diversity and an expansion in humans. Nature Genetics 27, 155–156.
Kivisild, T., Shen, P., Wall, D.P., Do, B., Sung, R., Davis, K., Passarino, G., Underhill, P.A., Scharfe, C., Torroni, A., Scozzari, R., Modiano, D., Coppa, A., de Knijff, P., Feldman, M., Cavalli-Sforza, L.L., Oefner, P.J., 2006. The role of selection in the evolution of human mitochondrial genomes. Genetics 172, 373-387.
Lewontin, R., 1972. The apportionment of human diversity. Evolutionary Biology 6: 381-398.
Melnick, D.J., Hoelzer, G.A., 1993. What is mtDNA good for in the study of primate evolution? Evolutionary Anthropology 2, 2-10.
Serre, D., Pääbo, S., 2004. Evidence for gradients of human genetic diversity within and among continents. Genome Research 14, 1679-1685.
Tishkoff, S., Deitzsch, E., Speed, W., Pakstis, A., Kidd, J., Cheung, K., Bonne-Tamir, M., Santachiara-Benerecetti, A., Moral, P., Krings, M., Paabo, S., Watson, E., Reisch, N., Jenkins, T., Kidd, K., 1996. Global patterns of linkage disequilibrium at the CD4 locus and modern human origins. Science 271, 1380-1387.
Tishkoff, S.A., Reed, F.A., Friedlaender, F.R., Ehret, C., Ranciaro, A., Froment, A., Hirbo, J.B., Awomoyi, A.A., Bodo, J-M., Doumbo, O., Ibrahim, M., Juma, A.T., Kotze, M.J., Lema, G., Moore, J.H., Mortensen, H., Nyambo, T.B., Omar, S.A., Powell, K., Pretorius, G.S., Smith, M.W., Thera, M.A., Wambebe, C., Weber, J.L., and Williams, S.M. 2009. The genetic structure and history of Africans and African Americans. Science 324, 1035-1044.
Underhill, P.A., Shen, P., Lin, A.A., Jin, L., Passarino, G., Yang, W.H., Kauffman, E., Bonné-Tamir, B., Bertranpetit, J., Francalacci, P., Ibrahim, M., Jenkins, T., Kidd, J.R., Mehdi, S.Q., Seielstad, M.T., Wells, R.S., Piazza, A., Davis, R.W., Feldman, M.W., Cavalli-Sforza, L.L., Oefner, P.J., 2000. Y chromosome sequence variation and the history of human populations. Nature Genetics 26, 358-361.
Whitfield, L., Sulston, J., Goodfellow, P., 1995. A recent common ancestry for human Y chromosomes. Nature 378, 379-380.
Human Skin Color Variation
The DNA of all people around the world contains a record of how living populations are related to one another, and how far back those genetic relationships go. Understanding the spread of modern human populations relies on the identification of genetic markers, which are rare mutations to DNA that are passed on through generations. Different populations carry distinct markers. Once markers have been identified, they can be traced back in time to their origin – the most recent common ancestor of everyone who carries the marker. Following these markers through the generations reveals a genetic tree of many diverse branches, each of which may be followed back to where they all join – a common African root.
The mitochondria inside each cell are the power stations of the body; they generate the energy necessary for cellular organisms to live and function. Mitochondria have their own DNA, abbreviated mtDNA, distinct from the DNA inside the nucleus of each cell. mtDNA is the female equivalent of a surname: it passes down from mother to offspring in every generation, and the more female offspring a mother and her female descendants produce, the more common her mtDNA type will become. But surnames mutate across many generations, and so mtDNA types have changed over the millennia. A natural mutation modifying the mtDNA in the reproductive cells of one woman will from then on characterize her descendants. These two fundamentals – inheritance along the mother line and occasional mutation – allow geneticists to reconstruct ancient genetic prehistory from the variations in mtDNA types that occur today around the world.
Population genetics often use haplogroups, which are branches on the tree of early human migrations and genetic evolution. They are defined by genetic mutations or "markers" found in molecular testing of chromosomes and mtDNA. These markers link the members of a haplogroup back to the marker's first appearance in the group's most recent common ancestor. Haplogroups often have a geographic relation.
A synthesis of mtDNA studies concluded that an early exodus out of Africa, evidenced by the remains at Skhul and Qafzeh by 135,000 to 100,000 years ago, has not left any descendants in today’s Eurasian mtDNA pool. By contrast, the successful exodus of women carrying M and N mtDNA, ancestral to all non-African mtDNA today, at around 60,000 years ago may coincide with the unprecedented low sea-levels at that time, probably opening a route across the Red Sea to Yemen. Another study of the a subset of the human mtDNA sequence yielded similar results, finding that the most recent common ancestor of all the Eurasian, American, Australian, Papua New Guinean, and African lineages dates to between 73,000 and 57,000 years ago, while the average age of convergence, or coalescence time, of the three basic non-African founding haplogroups M, N, and R is 45,000 years ago.
This information has enabled scientists to develop intriguing hypotheses about when dispersals took place to different regions of the world. These hypotheses can be tested with further studies of genetics and fossils.
Modern Human Diversity - Skin Color
Why do people from different parts of the world have different colored skin? Why do people from the tropics generally have darker skin color that those who live in colder climates? Variations in human skin color are adaptive traits that correlate closely with geography and the sun’s ultraviolet (UV) radiation.
As early humans moved into hot, open environments in search of food and water, one big challenge was keeping cool. The adaptation that was favored involved an increase in the number of sweat glands on the skin while at the same time reducing the amount of body hair. With less hair, perspiration could evaporate more easily and cool the body more efficiently. But this less-hairy skin was a problem because it was exposed to a very strong sun, especially in lands near the equator. Since strong sun exposure damages the body, the solution was to evolve skin that was permanently dark so as to protect against the sun’s more damaging rays.
Melanin, the skin's brown pigment, is a natural sunscreen that protects tropical peoples from the many harmful effects of ultraviolet (UV) rays. UV rays can, for example, strip away folic acid, a nutrient essential to the development of healthy fetuses. Yet when a certain amount of UV rays penetrates the skin, it helps the human body use vitamin D to absorb the calcium necessary for strong bones. This delicate balancing act explains why the peoples that migrated to colder geographic zones with less sunlight developed lighter skin color. As people moved to areas farther from the equator with lower UV levels, natural selection favored lighter skin which allowed UV rays to penetrate and produce essential vitamin D. The darker skin of peoples who lived closer to the equator was important in preventing folate deficiency. Measures of skin reflectance, a way to quantify skin color by measuring the amount of light it reflects, in people around the world support this idea. While UV rays can cause skin cancer, because skin cancer usually affects people after they have had children, it likely had little effect on the evolution of skin color because evolution favors changes that improve reproductive success.
There is also a third factor which affects skin color: coastal peoples who eat diets rich in seafood enjoy this alternate source of vitamin D. That means that some Arctic peoples, such as native peoples of Alaska and Canada, can afford to remain dark-skinned even in low UV areas. In the summer they get high levels of UV rays reflected from the surface of snow and ice, and their dark skin protects them from this reflected light.
Modern Human Diversity - Genetics
People today look remarkably diverse on the outside. But how much of this diversity is genetically encoded? How deep are these differences between human groups? First, compared with many other mammalian species, humans are genetically far less diverse – a counterintuitive finding, given our large population and worldwide distribution. For example, the subspecies of the chimpanzee that lives just in central Africa, Pan troglodytes troglodytes, has higher levels of diversity than do humans globally, and the genetic differentiation between the western (P. t. verus) and central (P. t. troglodytes) subspecies of chimpanzees is much greater than that between human populations.
Early studies of human diversity showed that most genetic diversity was found between individuals rather than between populations or continents and that variation in human diversity is best described by geographic gradients, or clines. A wide-ranging study published in 2004 found that 87.6% percent of the total modern human genetic diversity is accounted for by the differences between individuals, and only 9.2% between continents. In general, 5%–15% of genetic variation occurs between large groups living on different continents, with the remaining majority of the variation occurring within such groups (Lewontin 1972; Jorde et al. 2000a; Hinds et al. 2005). These results show that when individuals are sampled from around the globe, the pattern seen is not a matter of discrete clusters – but rather gradients in genetic variation (gradual geographic variations in allele frequencies) that extend over the entire world. Therefore, there is no reason to assume that major genetic discontinuities exist between peoples on different continents or "races." The authors of the 2004 study say that they ‘see no reason to assume that "races" represent any units of relevance for understanding human genetic history. An exception may be genes where different selection regimes have acted in different geographical regions. However, even in those cases, the genetic discontinuities seen are generally not "racial" or continental in nature but depend on historical and cultural factors that are more local in nature’ (Serre and Pääbo 2004: 1683-1684).
Web Resources
http://www.understandingrace.org/humvar/
http://www.indiana.edu/~arch/saa/matrix/aea/aea_syl.html
https://www3.nationalgeographic.com/genographic/index.html
Bibliography
Cann, R., Stoneking, M., Wilson, A., 1987. Mitochondrial DNA and human evolution. Nature 352, 31-36.
Cavalli-Sforza, L.L., Menozzi, P., Piazza, A., 1994. The History and Geography of Human Genes. Princeton University Press, Princeton, NJ.
Ebersberger, I., Metzler, D., Schwarz, C., Pääbo, S., 2002. Genomewide comparison of DNA sequences between humans and chimpanzees. American Journal of Human Genetics 70, 1490–1497.
Fischer, A., Wiebe, V., Pääbo, S., Przeworski, M., 2004. Evidence for a complex demographic history of chimpanzees. Molecular Biology and Evolution 21, 799-808.
Forster, P., 2004. Ice Ages and the mitochondrial DNA chronology of human dispersals: a review. Philosophical Transactions of the Royal Society of London B 359, 255–264.
Gonder, M.K., Mortensen, H.M., Reed, F.A., de Sousa, A., Tishkoff, S.A., 2007. Whole-mtDNA genome sequence analysis of ancient African lineages. Molecular Biology and Evolution 24, 757–768.
Hinds D.A., Stuve L.L., Nilsen G.B., Halperin E., Eskin E., Ballinger D.G., Frazer K.A., Cox D.R., 2005. Whole-genome patterns of common DNA variation in three human populations. Science 307, 1072–1079.
Ingman, M., Kaessmann, H., Pääbo, S., Gyllensten, U., 2000. Mitochondrial genome variation and the origin of modern humans. Nature 408, 708–713.
Ingman, M., Gyllensten, U., 2001. Analysis of the complete human mtDNA genome: methodology and inferences for human evolution. Journal of Heredity 2001:92, 454-461.
Jorde, L.B., Watkins, W.S., Bamshad, M.J., Dixon, M.E., Ricker, C.E., Seielstad, M.T., Batzer, M.A., 2000. The distribution of human genetic diversity: a comparison of mitochondrial, autosomal, and Y-chromosome data. American Journal of Human Genetics 66, 979–988.
Kaessmann, H., Heissig, F., von Haeseler, A., Pääbo, S., 1999. DNA sequence variation in a non-coding region of low recombination on the human X chromosome. Nature Genetics 22, 78-81.
Kaessmann, H., Wiebe, V., Weiss, G., Pääbo, S., 2001. Great ape DNA sequences reveal a reduced diversity and an expansion in humans. Nature Genetics 27, 155–156.
Kivisild, T., Shen, P., Wall, D.P., Do, B., Sung, R., Davis, K., Passarino, G., Underhill, P.A., Scharfe, C., Torroni, A., Scozzari, R., Modiano, D., Coppa, A., de Knijff, P., Feldman, M., Cavalli-Sforza, L.L., Oefner, P.J., 2006. The role of selection in the evolution of human mitochondrial genomes. Genetics 172, 373-387.
Lewontin, R., 1972. The apportionment of human diversity. Evolutionary Biology 6: 381-398.
Melnick, D.J., Hoelzer, G.A., 1993. What is mtDNA good for in the study of primate evolution? Evolutionary Anthropology 2, 2-10.
Serre, D., Pääbo, S., 2004. Evidence for gradients of human genetic diversity within and among continents. Genome Research 14, 1679-1685.
Tishkoff, S., Deitzsch, E., Speed, W., Pakstis, A., Kidd, J., Cheung, K., Bonne-Tamir, M., Santachiara-Benerecetti, A., Moral, P., Krings, M., Paabo, S., Watson, E., Reisch, N., Jenkins, T., Kidd, K., 1996. Global patterns of linkage disequilibrium at the CD4 locus and modern human origins. Science 271, 1380-1387.
Tishkoff, S.A., Reed, F.A., Friedlaender, F.R., Ehret, C., Ranciaro, A., Froment, A., Hirbo, J.B., Awomoyi, A.A., Bodo, J-M., Doumbo, O., Ibrahim, M., Juma, A.T., Kotze, M.J., Lema, G., Moore, J.H., Mortensen, H., Nyambo, T.B., Omar, S.A., Powell, K., Pretorius, G.S., Smith, M.W., Thera, M.A., Wambebe, C., Weber, J.L., and Williams, S.M. 2009. The genetic structure and history of Africans and African Americans. Science 324, 1035-1044.
Underhill, P.A., Shen, P., Lin, A.A., Jin, L., Passarino, G., Yang, W.H., Kauffman, E., Bonné-Tamir, B., Bertranpetit, J., Francalacci, P., Ibrahim, M., Jenkins, T., Kidd, J.R., Mehdi, S.Q., Seielstad, M.T., Wells, R.S., Piazza, A., Davis, R.W., Feldman, M.W., Cavalli-Sforza, L.L., Oefner, P.J., 2000. Y chromosome sequence variation and the history of human populations. Nature Genetics 26, 358-361.
Whitfield, L., Sulston, J., Goodfellow, P., 1995. A recent common ancestry for human Y chromosomes. Nature 378, 379-380.
Wednesday, June 8, 2011
Reading Analysis Paper #1 Assignment
Student’s Name
World History, Andrews
RA #1
June 6, 2011
Analysis Paper
Develop a specific question from one of the assigned chapters in your textbook to analyze in more detail. Use quotes from the reading, as well as any outside research, as needed.
Your paper should be three double-spaced pages in length, including Header and Works Cited. Arial font, 11 point, is preferred. Times New Roman 12 point may also be used. Margins no greater than 1 inch, please. Examples of the proper format for your Header and Works Cited sections appear on this handout.
Works Cited
Aurelius, Marcus. “Meditations.” In Heritage of Western Civilizations. Ed. John L. Beatty and Oliver A. Johnson. Vol 1. 8th ed. New Jersey: Prentice Hall. 1995. 212-220.
Confucius. “The Analects.” In The Norton Anthology of World Masterpieces. Ed. Maynard Mack. New York. W.W. Norton & Company. 1997. 548-549.
Strayer, Robert. Ways of the World: A Brief Global History. Boston: Bedford/St. Martin’s. 2009.
World History, Andrews
RA #1
June 6, 2011
Analysis Paper
Develop a specific question from one of the assigned chapters in your textbook to analyze in more detail. Use quotes from the reading, as well as any outside research, as needed.
Your paper should be three double-spaced pages in length, including Header and Works Cited. Arial font, 11 point, is preferred. Times New Roman 12 point may also be used. Margins no greater than 1 inch, please. Examples of the proper format for your Header and Works Cited sections appear on this handout.
Works Cited
Aurelius, Marcus. “Meditations.” In Heritage of Western Civilizations. Ed. John L. Beatty and Oliver A. Johnson. Vol 1. 8th ed. New Jersey: Prentice Hall. 1995. 212-220.
Confucius. “The Analects.” In The Norton Anthology of World Masterpieces. Ed. Maynard Mack. New York. W.W. Norton & Company. 1997. 548-549.
Strayer, Robert. Ways of the World: A Brief Global History. Boston: Bedford/St. Martin’s. 2009.
Subscribe to:
Posts (Atom)