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Ancient Europeans More Diverse, Genetically Speaking, than Modern Ones

Text A. The Origin of Dogs | Text B. Gene Study Suggests Goats Got Around Through Early Human Commerce | Exercise 3. Now divide into pairs or small groups and read about each method. Then tell other students what you have read about. Try not to miss any detail. | Introduction. | Sleep disorders | Exercise 5. In the following text the paragraphs are mixed. Put them in the correct logical order. The first and the last paragraphs are in their right places. | Exercise 2. Read the following facts about caffeine and coffee trees to check your answers in Exercise 1. | Exercise 5. Read the article about health effects of coffee to check your answers in Exercise 4. | Exercise 6. In the following text the lines are mixed up. Put them in their proper order. The first and the last lines are in their correct places. | Text A. How Our Genomes Control Diversity |


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  6. ANCIENT BRITAIN

Bubonic plague may be responsible for reducing the genetic diversity of present-day Britons

By David Biello

Modern Britons are a cosmopolitan bunch. Peoples from across the globe now make the island home, bringing with them, theoretically, a diverse array of genes. (1) _____ Molecular ecologist Rus Hoelzel of Durham University in England and his European colleagues compared the genetic make up of six English ancestors from the Roman period, 25 from early in the Saxon conquest and 17 from the late Saxon period with the mitochondrial DNA sequences of more than 6,000 modern Europeans and Middle Easterners. "We found higher mitochondrial DNA diversity in ancient England (Roman to Saxon times) than in either modern England or in a combination of northern European countries," Hoelzel says. (2) _______

Even when present-day Europeans were broken down into 10 smaller samples of 48 individuals each, they still were less diverse than their ancestors. (3) ______; 6.3 percent of ancients carried it compared with nearly 22 percent of modern Britons and an average of nearly 19 percent of all Europeans.

The CRS haplotype imparts no known special traits in the humans who bear it, but the "black death" may have played a role in increasing its abundance in the modern population. (4) _____ The dread disease could either have increased the proportion of certain haplotypes somehow associated with increased survival or simply led to the extinction of rare haplotypes in families or villages who had a particular susceptibility, Hoelzel says.

Only three small groups—modern peoples from Belarus, Palestine and Turkey—showed similar levels of diversity to these early ancestors, though studies by others have shown that southern Europeans, such as Italians, seem to retain a broader pool of genetic material. (5) ______, according to researchers, the ancients possessed a more robust array of differing genetic stocks. (From Scientific American Online, August 1, 2007)

 

(a) The 48 ancients bore 36 different haplotypes—a set of variations in the genetic code. But their descendants more commonly carried one particular haplotype, known as Cambridge reference sequence (CRS)

(b) It is unclear exactly why contemporary Europeans are less genetically diverse despite a continuing influx of new populations but,

(c) This bubonic plague swept Britain (and all of Europe) in the 14th century, killing as much as half of the population, before recurring again in London in the 17th century.

(d) “Modern human populations are highly diverse, just less so in northern Europe, at least, than the ancient populations in England."

(e) But comparing the genetic material of more than 1,000 contemporary Englishmen with that of 48 of their ancient peers reveals that the ancients had even more diverse genetic codes.

 


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Text B. Ethnic Differences Traced to Variable Gene Expression| Exercise 7. In the following text the lines are mixed up. Put them in the correct order.

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