Read the following text.Choose the best word(s)for each numbered blank and mark A,B,C or D on the ANSWER SHEET.(10 points)
①Though not biologically related,friends are as"related"as fourth cousins,sharing about 1%of genes.②That is 1 a study,published from the University of California and Yale University in the Proceedings of the National Academy of Sciences,has 2.
①The study is a genome-wide analysis conducted 3 1,932 unique subjects which 4 pairs of unrelated friends and unrelated strangers.②The same people were used in both 5.
①While 1%may seem 6,it is not so to a geneticist.②As James Fowler,professor of medical genetics at UC San Diego,says,"Most people do not even 7 their fourth cousins but somehow manage to select as friends the people who 8 our kin."
①The study 9 found that the genes for smell were something shared in friends but not genes for immunity.②Why this similarity exists in smell genes is difficult to explain,for now.③10,as the team suggests,it draws us to similar environments but there is more 11 it.④There could be many mechanisms working together that 12 us in choosing genetically similar friends 13"functional kinship"of being friends with 14!
①One of the remarkable findings of the study was that the similar genes seem to be evolving 15 than other genes.②Studying this could help 16 why human evolution picked pace in the last 30,000 years,with social environment being a major 17 factor.
①The findings do not simply explain people’s 18 to befriend those of similar 19 backgrounds,say the researchers.②Though all the subjects were drawn from a population of European extraction,care was taken to 20 that all subjects,friends and strangers were taken from the same population.③The team also controlled the data to check ancestry of subjects.
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