The idea that some groups of people may be more intelligent than others is one of those hypotheses that dare not speak its name. But Gregory Cochran is【C1】______to say it anyway. He is that【C2】______bird, a scientist who works independently【C3】______any institution. He helped popularize the idea that some diseases not【C4】______thought to have a bacterial cause were actually infections, which aroused much controversy when it was first suggested. 【C5】______he, however, might tremble at the【C6】______of what he is about to do. Together with another two scientists, he is publishing a paper which not only【C7】______that one group of humanity is more intelligent than the others, but explains the process that has brought this about. The group in【C8】______is a particular people originated from central Europe. The process is natural selection. This group generally does well in IQ test, 【C9】______12-15 points above the【C10】______value of 100, and have contributed【C11】______to the intellectual and cultural life of the West, as the【C12】______of their elites, including several world-renowned scientists, 【C13】______They also suffer more often than most people from a number of nasty genetic diseases, such as breast cancer. These facts, 【C14】______, have previously been thought unrelated. The former has been【C15】______to social effects, such as a strong tradition of【C16】______education. The latter was seen as a(an) 【C17】______of genetic isolation. Dr. Cochran suggests that the intelligence and diseases are intimately【C18】______. His argument is that the unusual history of these people has【C19】______them to unique evolutionary pressures that have resulted in this【C20】______state of affairs.【C10】