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新视野大学英语4课文unit 7 Research into Population Genetics

新视野大学英语_新视野大学英语4课文unit 7 Research into Population Genetics

Section A:
Research into Population Genetics
While not exactly a top selling book, The History and Geography of Human Genes is a remarkable collection of more than 50 years of research in population genetics. It stands as the most extensive survey to date on how humans vary at the level of their genes. The book's firm conclusion: once the genes for surface features such as skin color and height are discounted, the "races" are remarkably alike under the skin. The variation among individuals is much greater than the differences among groups. In fact, there is no scientific basis for theories pushing the genetic superiority of any one population over another.
The book, however, is much more than an argument against the latest racially biased theory. The prime mover behind the project, Luca Cavalli-Sforza, a Stanford professor, labored with his colleagues for 16 years to create nothing less than the first genetic map of the world. The book features more than 500 maps that show areas of genetic similarity — much as places of equal altitude are shown by the same color on other maps. By measuring how closely current populations are related, the authors trace the routes by which early humans migrated around the earth. Result: the closest thing we have to a global family tree.
The information needed to draw that tree is found in human blood: various proteins that serve as markers to reveal a person's genetic makeup. Using data collected by scientists over decades, the authors assembled profiles of hundreds of thousands of individuals from almost 2,000 groups. And to ensure the populations were "pure", the study was confined to groups that were in their present locations as of 1492, before the first major movements from Europe began — in effect, a genetic photo of the world when Columbus sailed for America.
Collecting blood, particularly from ancient populations in remote areas, was not always easy; potential donors were often afraid to cooperate, or raised religious concerns. On one occasion, when Cavalli-Sforza was taking blood samples from children in a rural region of Africa, he was confronted by an angry farmer waving an axe. Recalls the scientist: "I remember him saying, ’If you take the blood of the children, I'll take yours.’ He was worried that we might want to do some magic with the blood."
Despite the difficulties, the scientists made some remarkable discoveries. One of them jumps right off the book's cover: a color map of the world's genetic variation has Africa at one end of the range and Australia at the other. Because Australia's native people and black Africans share such superficial characteristics as skin color and body shape, they were widely assumed to be closely related. But their genes tell a different story. Of all humans, Australians are most distant from the Africans and most closely resemble their neighbors, the Southeast Asians. What the eye sees as racial differences — between Europeans and Africans, for example — are mainly a way to adapt to climate as humans move from one continent to another.
The same map, in combination with ancient human bones, confirms that Africa was the birthplace of humanity and thus the starting point of the original human movements. Those findings, plus the great genetic distance between present-day Africans and non-Africans, indicate that the split from the African branch is the oldest on the human family tree.
The genetic maps also shed new light on the origins of populations that have long puzzled scientists. Example: the Khoisan people of southern Africa. Many scientists consider the Khoisan a distinct race of very ancient origin. The unique character of the clicking sounds in their language has persuaded some researchers that the Khoisan people are directly descended from the most primitive human ancestors. But their genes beg to differ. They show that the Khoisan may be a very ancient mix of west Asians and black Africans. A genetic trail visible on the maps shows that the breeding ground for this mixed population probably lies in Ethiopia or the Middle East.
The most distinctive members of the European branch of the human tree are the Basques of France and Spain. They show unusual patterns for several genes, including the highest rate of a rare blood type. Their language is of unknown origin and cannot be placed within any standard classification. And the fact that they live in a region next to famous caves which contain vivid paintings from Europe's early humans, leads Cavalli-Sforza to the following conclusion: "The Basques are extremely likely to be the most direct relatives of the Cro-Magnon people, among the first modern humans in Europe." All Europeans are thought to be a mixed population, with 65% Asian and 35% African genes.
In addition to telling us about our origins, genetic information is also the latest raw material of the medical industry, which hopes to use human DNA to build specialized proteins that may have some value as disease-fighting drugs. Activists for native populations fear that the scientists could exploit these peoples: genetic material taken from blood samples could be used for commercial purposes without adequate payment made to the groups that provide the DNA.
Cavalli-Sforza stresses that his mission is not just scientific but social as well. The study's ultimate aim, he says, is to "weaken conventional notions of race" that cause racial prejudice. It is a goal that he hopes will be welcomed among native peoples who have long struggled for the same end.

英语学习

Section A:
Research into Population Genetics
While not exactly a top selling book, The History and Geography of Human Genes is a remarkable collection of more than 50 years of research in population genetics. It stands as the most extensive survey to date on how humans vary at the level of their genes. The book's firm conclusion: once the genes for surface features such as skin color and height are discounted, the "races" are remarkably alike under the skin. The variation among individuals is much greater than the differences among groups. In fact, there is no scientific basis for theories pushing the genetic superiority of any one population over another.
The book, however, is much more than an argument against the latest racially biased theory. The prime mover behind the project, Luca Cavalli-Sforza, a Stanford professor, labored with his colleagues for 16 years to create nothing less than the first genetic map of the world. The book features more than 500 maps that show areas of genetic similarity — much as places of equal altitude are shown by the same color on other maps. By measuring how closely current populations are related, the authors trace the routes by which early humans migrated around the earth. Result: the closest thing we have to a global family tree.
The information needed to draw that tree is found in human blood: various proteins that serve as markers to reveal a person's genetic makeup. Using data collected by scientists over decades, the authors assembled profiles of hundreds of thousands of individuals from almost 2,000 groups. And to ensure the populations were "pure", the study was confined to groups that were in their present locations as of 1492, before the first major movements from Europe began — in effect, a genetic photo of the world when Columbus sailed for America.
Collecting blood, particularly from ancient populations in remote areas, was not always easy; potential donors were often afraid to cooperate, or raised religious concerns. On one occasion, when Cavalli-Sforza was taking blood samples from children in a rural region of Africa, he was confronted by an angry farmer waving an axe. Recalls the scientist: "I remember him saying, ’If you take the blood of the children, I'll take yours.’ He was worried that we might want to do some magic with the blood."
Despite the difficulties, the scientists made some remarkable discoveries. One of them jumps right off the book's cover: a color map of the world's genetic variation has Africa at one end of the range and Australia at the other. Because Australia's native people and black Africans share such superficial characteristics as skin color and body shape, they were widely assumed to be closely related. But their genes tell a different story. Of all humans, Australians are most distant from the Africans and most closely resemble their neighbors, the Southeast Asians. What the eye sees as racial differences — between Europeans and Africans, for example — are mainly a way to adapt to climate as humans move from one continent to another.
The same map, in combination with ancient human bones, confirms that Africa was the birthplace of humanity and thus the starting point of the original human movements. Those findings, plus the great genetic distance between present-day Africans and non-Africans, indicate that the split from the African branch is the oldest on the human family tree.
The genetic maps also shed new light on the origins of populations that have long puzzled scientists. Example: the Khoisan people of southern Africa. Many scientists consider the Khoisan a distinct race of very ancient origin. The unique character of the clicking sounds in their language has persuaded some researchers that the Khoisan people are directly descended from the most primitive human ancestors. But their genes beg to differ. They show that the Khoisan may be a very ancient mix of west Asians and black Africans. A genetic trail visible on the maps shows that the breeding ground for this mixed population probably lies in Ethiopia or the Middle East.
The most distinctive members of the European branch of the human tree are the Basques of France and Spain. They show unusual patterns for several genes, including the highest rate of a rare blood type. Their language is of unknown origin and cannot be placed within any standard classification. And the fact that they live in a region next to famous caves which contain vivid paintings from Europe's early humans, leads Cavalli-Sforza to the following conclusion: "The Basques are extremely likely to be the most direct relatives of the Cro-Magnon people, among the first modern humans in Europe." All Europeans are thought to be a mixed population, with 65% Asian and 35% African genes.
In addition to telling us about our origins, genetic information is also the latest raw material of the medical industry, which hopes to use human DNA to build specialized proteins that may have some value as disease-fighting drugs. Activists for native populations fear that the scientists could exploit these peoples: genetic material taken from blood samples could be used for commercial purposes without adequate payment made to the groups that provide the DNA.
Cavalli-Sforza stresses that his mission is not just scientific but social as well. The study's ultimate aim, he says, is to "weaken conventional notions of race" that cause racial prejudice. It is a goal that he hopes will be welcomed among native peoples who have long struggled for the same end.

英语学习

Section B:
Geniuses and Better Parenting
It is a popular myth that great geniuses — the Einsteins, Picassos and Mozarts of this world — spring up out of nowhere as if touched by the finger of God. The model is Karl Friedrich Gauss, supposedly born into a family of manual workers, who grew up to become the father of modern mathematics.
A professor who studies early learning has attacked this myth, saying that when he looked into Gauss's childhood, he found that Gauss's mother had been teaching him numbers at the age of two. His father had supervised manual workers, not been one, and played calculation games with him. Furthermore, Gauss had an educated uncle who taught him sophisticated math at an early age.
It is the same story with other geniuses. Einstein's father was an electrical engineer who fascinated his son with practical displays of physics. Picasso's father was an art teacher who had young Pablo painting bowls of fruit at the age of eight. Mozart's father was a musician employed at a noble's court who was teaching his son to sing and play almost before he could walk. "In every case, when you look into the backgrounds of great people, there is this pattern of very early stimulation by a parent or teacher figure," the professor says.
But what sort of parental stimulation should it be? There is plenty of evidence that, too often, pressure from parents results in children suffering fatigue rather than becoming geniuses. One study has identified two kinds of parent style — the supportive and the stimulating.
Supportive parents were those who would go out of their way to help their children follow their favorite interests and praised whatever level of achievement resulted. Generally, such parents created a pleasant home governed by clear rules. Stimulating parents were more actively involved in what their children did, steering them towards certain fields and pushing them to work hard, often acting as a tutor.
The study followed four groups of children: one with supportive parents, one with stimulating parents, one whose parents combined both qualities and a final group who offered neither. The children were given electronic devices; when these made a sound, they had to make a note of what they were doing and assess how happy and alert they felt.
The not too surprising result was that the children whose parents were simply supportive were happier than average but were not particularly intense in their concentration when studying or working on something. The children who fared best were those whose parents were both supportive and stimulating. These children showed a reasonable level of happiness and were very alert during periods of study.
Children whose parents were stimulating without being supportive were candidates for fatigue. These children did work long hours, but their alertness and happiness during study time was far below that of children in more balanced family environments.
Another crucial factor is the need for parents to have proper conversations with their children. Through having the chance to talk with adults, children pick up not only language skills but also adult habits and styles of thought. One reason why prodigies such as Picasso and Einstein had a head start in life was that they had parents who demonstrated how to think about subjects like art or physics at a very early age.
A survey in Holland showed that a typical father spent just 11 seconds a day in conversation with his children. A more recent study in America produced a somewhat better result, but the fathers in question were still talking to their children for less than a minute a day.
It is not just the time spent that counts, but also the way in which a parent talks. A parent who only gives a brief reply to a child's questions or gives dull answers will be passing on a negative, narrow-minded style of thinking. On the other hand, parents happy to take a child step by step through an argument, encouraging him or her to explore ideas, will cultivate an open and creative thinking style.
One researcher is attempting to show this experimentally with a study in which groups of parents are taught how to have beneficial conversations with their small children. He says these children have an advantage over their peer group in language ability, intellectual ability, and even social leadership skills. While the study is not yet complete, the children appear to have been given a long-term advantage.
So what is the outlook for parents who do everything right, those who manage to be both supportive and stimulating, who are good at demonstrating thinking skills to their children and successful at cultivating a self-motivated approach to learning? Would such parents be guaranteed to have a genius as their child?
There is general agreement that genuine biological differences exist between individuals; geniuses need to be lucky in both their genes and their parents. The most significant implication would seem to be that while most people are in a good position to fulfill their biological potential — barring serious illnesses or a poor diet during childhood — it is far from certain that they will grow up in an environment where that capacity will be developed.
So although knowing more about the biology of genius is all very interesting, it is research into better parenting and educational techniques that will have lasting significance.

英语学习

Section C:
Genetics and Environmental Factors in Creating Genius
Dr. Howard Gardner of Harvard University believes that geniuses are largely made. He has banned television from his home because he fears it might ruin the minds of his family. He makes time every day to listen to his seven-year-old son play the piano — even if it is no more than a few minutes during a phone call while he is away at a conference.
Dr. Sandra Scarr of Virginia University(弗吉尼亚大学), president of the Society for Research in Child Development(儿童发展研究会主席), believes geniuses are largely born. She says parents should not worry too much about whether to take their kids to a ball game or to a museum. Talent will out.
It seems experts are as divided as ever over the issue of which is more important, environment or genetics. This may, however, be about to change. A conference organized earlier this year brought to London some of the biggest names from both sides of the debate. Amazing results from unpublished work were revealed — and the beginning of agreement could be perceived.
The most exciting results came from those working on the biology of individual differences. Dr. Robert Plomin of Penn State University(宾夕法尼亚州立大学), hopes to announce within the next few months that he has tracked down one of the genes that plays a part in determining intelligence. A gene has been identified but the results have yet to be confirmed.
At present, it is believed that genes account for at least half of what researchers call "g" — the general thinking ability that IQ tests are supposed to measure — while environmental influences account for the other half. But so far the only evidence for a genetic component has been through statistics, the relationship being inferred mathematically from comparisons of twins and other such studies of close relatives. Plomin's method makes use of new gene mapping techniques and promises to provide direct evidence of the role that genes play.
Plomin stresses that the discovery of a first gene does not mean the puzzle of intelligence has been solved. A single gene will code for only one of the many molecules and cell proteins that are the building blocks of the brain. This means that hundreds, if not thousands, of genes must be involved in intelligence. The identification of even one gene does, however, have immense implications for the genetics/environment debate.
Another advance, a computer-controlled brain scanning device, has led to a second discovery by those seeking the biological component of mental abilities. Professor Camilla Benbow of Iowa State University(爱荷华州立大学) is head of a long-term study of children who are unusually good at math. For many years she has been puzzled as to why so many of the children in her study should be boys — at the top level, there are more boys than girls by a ratio of thirteen to one. In a soon-to-be-published paper, Benbow reveals that the talented boys' brains appear to process information concerning the location of objects in a very different way from those of average boys and even of talented girls.
The brains of children in the study were scanned while being presented with a simple visual puzzle. The boys of average ability and the gifted girls showed strong activity on both sides of their brains as they thought about the puzzle. However, the gifted boys responded very differently. There was a sudden drop in activity in the left side of the brain — the side most involved in language — and an exaggerated reaction on the right, the side strongest at thinking about the location of objects. It seems that the brains of boys with mathematical talent operate in a way that is physically unique.
Benbow says she was surprised that the talented girls should lack this pattern of response. The only explanation she has is that male brains have a tendency to become more divided during development, with different functions located on one side of the brain or the other. When this division is taken to an extreme, unusual mathematical abilities result.
Because females do not have this tendency (this brain division is known to be influenced by male sex chemicals), girls who perform well in mathematics are doing so because they are superior in their overall mental development. And because such all-round ability is less common, this would be the reason for there being fewer mathematically talented girls.
Benbow is quick to add, however, that cultural expectations probably exaggerate the difference. In China, where girls are more likely to get encouragement in mathematics, the number of gifted boys exceeds that of gifted girls by four to one, rather than the thirteen to one seen in the United States.
Both Plomin's and Benbow's findings would seem to give support to the argument that outstanding mental abilities are largely the result of genetics. But the conference heard equally strong evidence for the role that environmental factors play in creating genius. A theme repeatedly heard from the speakers was that special children invariably have special parents.

英语学习
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