15 January 2011

Unhealthful News 15 - Extraordinary claims require extraordinary evidence, unless they are political

Chris Snowdon called my attention to this article describing research that led its author, Oxford prof Avner Offer, to conclude he had demonstrated that obesity is caused by insecurity about money.  What extraordinary evidence was used to sort through the tangle of causes – lack of youthful play, large portion sizes of food, long hours working in front of computers, sugary drinks, Happy Meals, limited access to healthy food, etc. – to be able to tease out the effects of financial insecurity?  A collection of 96 survey results spread over a decade in 11 countries, with the measure of exposure being how "market liberal" the countries are.

Apparently Offer has a pet theory that because other animals (including our potentially starving ancestors and, sadly, contemporaries in today's world) sensibly gorge themselves when the opportunity presents itself if they worry that they are at risk of starvation later, then perhaps people in rich countries will have that same overeating reaction if they are worried about their wealth.  It is a cute idea.  Even though these individuals face no serious prospect of starvation in their lives, worrying about wealth might tweak the worry-about-food triggers we evolved.  It seems like rather a stretch to me, though.  I would guess that that urge to gorge and get fat, which we know is triggered by having experienced actual starvation episodes, would not be triggered by vague feelings that things are a little uncertain.  After all, our evolution programed us to deal with not only uncertainty about food, but also about  protecting ourselves from threats, protecting our families, finding mates, etc., so not all feelings of uncertainty would translate into "eat more now!"

Still, there is nothing wrong with testing a cute theory.  The problem is that they did not really do so.

The conclusion was that the more "market liberal" countries, which the author implicitly translates into people worrying about economic security though even this is a stretch, like the U.S. and Canada have more fat people than do welfare states like France or Sweden.  Of course it could have something to do with the fact that when you get served a meal in North America it could often feed two or three people and comes with free refills of Coke, or that few people walk anywhere (I suspect that the correlation with per capita gasoline consumption is stronger than the "market liberal" effect).  Meanwhile in France or Italy, meals are reasonable and savored and blah blah blah [insert your choice of standard boilerplate about why the French and Italians are healthy despite all the cheese and booze] while in Sweden the food is so darn salty that you will die of hypertension before you can get fat.  (For the record, I just make that last part up, but it is amazing how much salt they like.)  This perhaps does not explain Britain being listed on the fat and liberal side of the divide, with lots of walking in the cities and food that is, well, not exactly gorge-worthy.  But that observation is hardly enough to conclude that a subtle subconscious feeling wealth insecurity causes obesity, rather than the more obvious explanations.

Snowdon has thoroughly debunked the darling-of-the-left political broadside (pretending to be epidemiologic science) that claims wealth inequality per se (that is, apart from actual poverty) causes health problems.  I suspect he would make some interesting observations about Offer's data also – little matters like obese Britain has a wealth-security-protecting welfare state that is much more similar to France than with the USA, despite being categorized with the latter.  Perhaps it is also worth mentioning that America has its own non-free-market welfare policies, but since they favor producers of corn and beef and such (farm subsidies, school lunches), they definitely are pro-obesity.

But even if the analysis were done as best as could possibly be done, the conclusion is quite an extraordinary claim.  In Unhealthful News 6 and Unhealthful News 7 I wrote about the discussion surrounding recent publication of research results that suggested future events could affect current thoughts (i.e., ESP).  Some people went nuts about this, offended that the research would even be published.  They screamed "extraordinary claims require extraordinary evidence!"  Well, yeah, but it is not like anyone claimed to have established the claim that ESP happens.  But the researcher did design some experiments that were optimized to test some specific extraordinary phenomena and minimize other possible causes, and the results of those studies was reported for anyone to assess.  Contrast that with the Offer study, in which he collected some vague data that kinda sorta maybe points in the direction of his hypothesis, if you analyze it in a particular way ignore all the other possible explanations; his claim was reported as if it had been clearly demonstrated.

I suspect that many of my colleagues would argue that this is not surprising:  The media and politicized public health types always accept claims that some health study supports a favorite theory of the illiberal left political faction.  But I am pretty sure that the media and pundits (though perhaps different ones) would report, with as much naive conclusiveness, equally sketchy evidence that the welfare state was causing obesity.  I think the issue is not left-vs-right, but natural science-vs-politics and social science.  In grade school in America (and to the extent I know, elsewhere), science education focuses on simplistic statements of what is true and false, factoids and simplistic disdain for popular myths, rather than actual scientific thinking.  As a result, decades later those who take science seriously have programmed visceral objections to anyone proposing something they learned was a myth (witness how animated the efforts are to responding to denials of evolution or belief in astrology - which we are taught to disbelieve in school - and how much more measured are efforts to dispel rather more immediately harmful myths about nutrition).  This reaction can be so strong that it becomes anti-science (look at how many people ferociously cling to disproved dietary myths about protein and "food groups" they were taught in schools, or attack the idea of doing research on ESP).  Meanwhile, kids are taught that political social science claims are based on whatever someone might want to say (we are all entitled to our opinions about the good society; somehow this translates into "we are all entitled to make up empirical economic claims").  Thus, bad ideas get equal time and never stay dead in the political discourse.

Frankly I consider it rather more reasonable to suggest that (a) there are important holes in our understanding of consciousness that might mean we learn something quite unexpected rather that (b) a measurable amount of obesity in rich countries where no one starves is caused by feelings of uncertainty resulting from freer economic policies per se (as opposed to the consequences of those policies, like poverty, cheap gasoline, and McDonalds).  I am not sure which shows greater hubris, the assumption that (a) is not true because 2011 represents the pinnacle of human knowledge and unlike those fools in 1911 who thought they knew everything about mind and physics, we really do, or that (b) is true because 96 data points let us sort out all the subtle causes of obesity.

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