I am not convinced that this argument is particularly good news for elders who may be 【C1】_____to enjoy the time of their lives. What maybe good news is perhaps best forgotten by those who are【C2】__on from day to day, and getting by as best as they【C3】__. Causation is itself an 【C4】__matter for the unscientific mind. Which would you rather feel: that your cancer has been genetically【C5】__, induced by stress or caused by viruses? Brought about by your own folly in smoking cigarettes, as Kirkwood himself appears to take【C6】__granted — brought about casually and spontaneously through the operation of chance? If it is put before them in this way, most people would rather not think about the matter at all. Kirkwood takes a different view, maintaining that the more we know about the【C7】__process, the more we can “【C8】__a greater degree of personal control”. Common sense certainly tells us oldies to take it easy, to cut【C9】__a bit on food and alcohol and strenuous exercise, but we know this from the feel of our【C10】_____rather than from what we read about the progress of science.

Though not biologically related, friends are as “related” as fourth cousins, sharing about 1% of genes. That is【C1】_____a study, published from the University of California and Yale University in the Proceedings of the National Academy of Sciences, has【C2】_____.

The study is a genome-wide analysis conducted【C3】_____1,932 unique subjects which【C4】__pairs of unrelated friends and unrelated strangers. The same people were used in both【C5】_____.

While 1% may seem【C6】_____, it is not so to a geneticist. As James Fowler, professor of medical genetics at UC San Diego, says “Most people do not even【C7】__their fourth cousins but somehow manage to select as friends the people who【C8】_____our kin.”

The study【C9】________found that the genes for smell were something shared in friends but not genes for immunity. Why this similarity exists in smell genes is difficult to explain, for now.

【C10】_____,as the team suggests, it draws us to similar environments but there is more【C11】_____it.

There could be many mechanisms working together that【C12】_____us in choosing genetically similar friends【C13】__“functional kinship” of being friends with【C14】_____!

One of the remarkable findings of the study was that the similar genes seem to be evolution 【C15】_____than other genes. Studying this could help【C16】__why human evolution picked pace in the last 30,000 years, with social environment being a major【C17】_____factor.

The findings do not simply explain people’s【C18】_____to befriend those of similar 【C19】__backgrounds, say the researchers. Though all the subjects were drawn from a population of European extraction, care was taken to【C20】_____that all subjects, friends and strangers, were taken from the same population.