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  3. A controversy erupted in the scientific community in early 1998 over the use of DNA (deoxyribonucleic acid) fingerprinting in cr

A controversy erupted in the scientific community in early 1998 over the use of DNA (deoxyribonucleic acid) fingerprinting in cr

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问题      A controversy erupted in the scientific community in early 1998 over the use of DNA (deoxyribonucleic acid) fingerprinting in criminal investigations. DNA fingerprinting was introduced in 1987 as a method to identify individuals based on a pattern seen in their DNA, the molecule of which genes are made. DNA is present in every cell of the body except red blood cells. DNA fingerprinting has been used successfully in various ways, such as to determine paternity (父亲的身份) where it is not clear who the father of a particular child is. However, it is in the area of criminal investigations that DNA fingerprinting has potentially powerful and controversial uses.
     DNA fingerprinting and other DNA analysis techniques have revolutionized criminal investigations by giving investigators powerful new tools in the attempt to prove guilt, not just establish innocence. When used in criminal investigations, a DNA fingerprint pattern from a suspect is compared with a DNA fingerprint pattern obtained from such material as hairs or blood found at the scene of a crime. A match between the two DNA samples can be used as evidence to convict a suspect.
     The controversy in 1998 stemmed from a report published in December 1991 by population geneticists Richard C. Lewontin of Harvard University in Cambridge, Mass, and Daniel L. Hartl of Washington University School of Medicine in St. Louis, Mo. Lewontin and Hartl called into question the methods to calculate how likely it is that a match between two DNA fingerprints might occur by chance alone. In particular, they argued that the current method Cannot properly determine the likelihood that two DNA samples will match because they came from the same individual rather than simply from two different individuals who are members of the same ethnic group. Lewontin and Hartl called for better surveys of DNA patterns.
     In response to their criticisms, population geneticists Ranajit Chakraborty of the University of Texas in Dallas and Kenneth K. Kidd of Yale University in New Haven, Conn. , argued that enough data are already available to show that the methods currently being used are adequate. In January 1998, however, the Federal Bureau of investigation and laboratories that conduct DNA tests announced that they would collect additional DNA samples from various ethnic groups in an attempt to resolve some of these questions. And, in April, the National Academy of Sciences called for strict standards and system of accreditation (鉴定合格) for DNA testing laboratories.  
To geneticists like Lewontin and Hartl, the current method ______.
选项 A、is not so convincing as to exclude the likelihood that two DNA samples can never come from two individuals
B、is beyond dispute because two individuals of the same ethnic group are likely to have the same DNA pattern
C、is not based on adequate scientific theory of genetics
D、is theoretically contradictory to what they have been studying
答案A
解析 题干中的Lewontin和Hartl出现在第三段，在该段中这两位基因学家认为，出现两个相类似的DNA指纹的可能性还是存在的．目前的方法还不能确定相似的DNA指纹是否来自同一人。由此推断，基因学家Lewontin和Hartl认为，目前的方法无法排除两个DNA样品是否可能来自两个人的可能性，故答案为A项。B项中所提到的目前的方法无可争议，是因为来自同一种族中两个个体很有可能有相同的DNA模式，这种说法过于肯定，不符合原文；C项、D项都不是这两位基因学家的看法。
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