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We Finally Know How Income Affects Health
What we knew before is wrong
In 1912, the American physician Isaac Adler noted with quiet curiosity that cases of lung cancer had seen “a decided increase”, and attributed the increase to alcohol and tobacco. But, he hesitated to establish a causal link between them, writing that the subject was “not yet ready for final judgment”.
We know today that smoking causes cancer. But, by 1960, only one-third of all U.S. doctors believed that there was any relationship between smoking and cancer. In fact, almost half of all American doctors still regularly smoked cigarettes.
We can blame the tobacco industry for generating most of this confusion.
But at least a part of the confusion comes from the challenge that researchers face in disentangling correlation from causation.
By now, everyone has heard the warning that “correlation does not imply causation”, which simply means that just because two things move together (or apart), it doesn’t follow that the movement of one causes the movement of the other.
This is where scientists became befuddled. Yes, there was growing evidence of a correlation between smoking and lung cancer but it would take animal experimentation, population studies, and cellular pathology reports before the…
