The reading passage is concentrated on the latest research development in population genetics. The passage can be broadly divided into five main parts: the theoretical significance of The History and Geography of Human Genes, the contribution of the book (the creation of the first genetic map of the world), the difficulties encountered in the process of conducting the research, the major contributions of the first genetic map and the conclusion (the social value of the research).
1. The first part is Paragraph 1. The author makes it clear that there is no scientific basis for theories pushing the genetic superiority of any one population over another according to the book, The History and Geography of Human Genes. That is a book containing a remarkable collection of more than 50 years of research in population genetics.
2. The second part is Paragraph 2, which deals with the exceptional work in the book: the creation of the first genetic map of the world that traced the routes of early humans’ migration to find the closest thing we have to a global family tree.
3. The third part consists of two paragraphs: Paragraphs 3 and 4. This part moves a bit backward to the work that is behind the scene. This can be taken as an inserted part, which tells us that the creative results came from the hard work over the years. Paragraph 3 tells us that to draw a global family tree, information should be collected from human blood. Scientists assembled profiles of hundreds of thousands of individuals from almost 2,000 groups over decades, confining the study to groups that were in their present locations as of 1492 to ensure the populations were “pure”. Paragraph 4 gives us one example about the difficulties encountered in collecting blood samples from ancient populations in remote areas. For instance, people in a rural region of Africa refused to take blood out of their children.
4. The fourth part is made up of five paragraphs, from Paragraphs 5 to 9. This is the major part of the essay, which lists 4 major contributions of the first genetic map of the world. Paragraph 5 is about some remarkable discoveries: 1) A color map of the world’s genetic variation has Africa at one end of the range and Australia at the other. 2) Australia’s native people and black Africans share such superficial characteristics 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. 3) The racial differences — between Europeans and Africans, for example — are mainly a way to adapt to climate as humans move from one continent to another. Paragraph 6 tells us that the same map confirms that Africa was the birthplace of humanity as a result of a study in combination with ancient human bones. Paragraphs 7 and 8 are about the fact that the genetic maps also shed new light on the origins of populations that have long puzzled scientists. Here the author offers two examples. The first example: through the study of the genetic map, the Khoisan people of southern Africa may be a very ancient mix of west Asians and black Africans instead of being directly descended from the most primitive human ancestors. The second example is in Paragraph 8. The genetic map shows the Basques of France and Spain are extremely likely to be the most direct relatives of the Cro-Magnon people, among the first modern humans in Europe.
5. The fifth part is the last paragraph, Paragraph 10. The research 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. The ending echoes what is stated in the beginning paragraph: no genetic superiority of any one population over another from the research conducted.
Now just have a look at the chart below:
