Friday, November 14, 2008
"The Thick die Quick"
This is the kind of scientific study that gives nightmares to politically correct people. Smarter people live longer, according to a long and extended study reported recently in an essay in Nature magazine (requires subscription). If you only have a paper subscription, the exact reference is Nature 456, 175-176 (13 November 2008). Before I get hauled over the coals for this, let me hasten to add that I am only the messenger. And for those without a Nature subscription here are the salient points. The result is the outcome of surveys done on more than a million people whose development has been followed for upwards of 20 years. 1. The simplest but by no means the only explanation is that intelligence is associated with more education, and thereafter with more professional occupations that might place the person in healthier environments. However, this is by no means the whole story. 2. People with higher intelligence might engage in more healthy behaviours. Evidence is accruing that people with higher intelligence in early life are more likely to have better diets, take more exercise, avoid accidents, give up smoking, engage in less binge drinking and put on less weight in adulthood. Again, this is not the whole story. 3. Mental test scores from early life might act as a record of insults to the brain that have occurred before that date. These insults — perinatal events, or the result of illnesses, accidents or deprivations before the mental testing — might be the fundamental cause behind both intelligence test scores and mortality risk. So far, little evidence supports this. Both birth weight (commonly used as a marker of fetal development) and parental social class (used as a marker of early-life circumstances) are correlated with intelligence test scores. But, when the associations between intelligence and mortality are adjusted for these factors, the association remains almost unaltered. Perhaps subsequent work may find better indicators of early-life tribulations that have more explanatory power. 4. Mental test scores obtained in youth might be an indicator of a well-put-together system. It is hypothesized that a well-wired body is more able to respond effectively to environmental insults. If none of this sounds convincing, it's because it's not meant to. These are empirical findings for which researchers are still trying to find explanations. As the writer is at pains to clarify a clear chain of causation from intelligence to health outcomes and then to death has not emerged. In fact, the new University of Edinburgh Centre for Cognitive Ageing and Cognitive Epidemiology, which opened on 1 September 2008 aims is to provide a forum and infrastructure to unpick the extent to which cognitive and other effects underlie different causes of mortality . Why do we die when we do, and to what extent is this question tractable? This is what these researchers are trying to discover. I should point out also that the author is careful is stressing that these are not the standard intelligence IQ tests that many of us have taken from cheap paperbacks which at one time used to flood the market, mostly propagated by enthusiasts of the now discredited field of Eugenics. These are scores from cognitive-ability tests (also known as intelligence tests or IQ tests) (which) have validity that is almost unequalled in psychology.