Antarctic ice suggested that ancient carbon dioxide had caused
warming. Now we know the temperature rise came first. John S.
Dykes  Scientists like to remind us not to confuse cause and
effect. But they're not immune from making that mistake
themselves. Last week, for example, a flurry of sociological
headlines emanating from a conference included the claim that
elderly Taiwanese people who shop every day are 27% less likely
to die over 10 years than those who shop once a week; and the
claim that 16-year-olds who read books at least once a month are
more likely to be in managerial jobs at 33 than those who read
no books at 16.  It would be tempting but rash to conclude that
shopping prevents death, rather than that ill health prevents
shopping; or that reading causes career success rather than that
a scholarly aptitude causes both reading and career success.
The nature-nurture debate has long been bedeviled by cause-
effect confusion, as exemplified by the old joke: I'm not
surprised that Johnny comes from a