Choice, Obesity & the Irrational Ape (Homo insensatus)

What I see in Nature is a magnificent structure that we can comprehend only very imperfectly, and that must fill a thinking person with a feeling of humility.

……………………………………………………………………………………. – Albert Einstein

Another irrational ape (imitating Rodin’s ‘The Thinker’)

Jonah Lehrer has written another great piece about our irrationality in decision making, and our emotional responses to avoiding loss. He writes:

From the perspective of economics, there is no good reason to weight gains and losses so differently. Opportunity costs (foregone gains) should be treated just like “out-of-pocket costs” (losses). But they aren’t – losses carry a particular emotional sting.”

Others have noted the importance of emotion involved in decision making, and how it affects our ability to intuit how our choices will make us feel. When someone suffers damage to the prefrontal cortex of their brain, both their emotions and decision-making abilities are impaired (Bechara et al 1997). What this suggests is that emotions and reason are linked, rather than oppositional. They inform each other. This all fits in with Dan Ariely’s view of humans as “predictably irrational.”

I’ve written previously about Ariely, but perhaps didn’t do his work justice before, so I wanted to highlight it again. His take-home message is that it’s important to understand not only our inherent physical limitations, but also our cognitive ones (see Nesse and Williams [1996] for examples: bad backs, senescence, etc.). Do yourself a favor and watch this video. It’s worth 17 minutes of your life.

If you can’t watch it, Ariely shows some great examples of how limited our brains are at detecting visual illusions and applying reason to making decisions. He then says:

Vision is one of the best things we do. We have a huge part of our brain dedicated to vision, bigger than is dedicated to anything else… and we are evolutionarily designed to do vision. And if we have these predictable, repeatable mistakes in vision, in which we’re so good at, what’s the chance that we don’t make even more mistakes in something we’re not as good at? For example, financial decision-making.”

Ariely’s research has profound implications. In spite of the forces swirling around us – our genes, neurotransmitters, hormones, epigenetics, personal and family histories, ecological variables, prenatal conditions, socioeconomic status, culture, and an array of other social forces – we still have a tendency to believe that we are the ultimate arbiters of our own behavior and choices. To an extent, that is true. It is also a source of comfort and resilience to believe that the locus of control resides within ourselves, particularly in times of despair (“I am the master of my fate/ I am the captain of my soul). However, our choices are often constrained, or at least nudged in certain directions by variables that lie outside of us (“There but for the grace of God go I”).

For example, consider the matter of obesity in the United States, where there is a tendency to see excessive weight gain largely as a matter of personal irresponsibility. Even health professionals who specialize in the study or management of obesity show strong implicit bias toward viewing overweight individuals as lazy and less intelligent (Schwartz et al. 2003). This suggests: (1) that obesity is viewed, at least subconsciously, as largely a matter of choice, and (2) there is a moral judgment associated with it, leading to it being stigmatized. However, it is interesting that obesity is not stigmatized everywhere; in cultures where food is scarce, big is often beautiful (Brown 1992). Therefore, perceptions of obesity are at least partially contingent on environmental circumstances that lie outside the individual. As is obesity itself.

If we view how rates of obesity have increased dramatically in recent decades in the U.S. (Wang & Beydoun 2007), it seems highly unlikely that the root cause is an epidemic of irresponsible choices. Obesity rates have even increased in children between 2 and 5 years old, and I don’t think anyone would argue that our toddlers are just not as responsible as they used to be (though I suppose one might say their parents are, but I think that argument falls flat as well).

Changing rates of obesity in U.S. adults (data from Wang & Beydoun, 2007)

Instead, it is likely that greater forces are at work here than a simple matter of making poor decisions, including changes in the food supply and the greater accessibility of non-physical leisure activities (keep in mind Ariely’s lesson about how the mere availability of different choices influences our decisions). Other social factors may also be in play. Christakis & Fowler (2007) utilized data from the Framingham Heart Study from 1971 to 2003 to demonstrate how people are influenced by weight gain within one’s social network. In a metaphoric sense then, obesity is contagious. This is not due to an infectious agent like a virus (though that seems to be a possibility as well [Gabbert et al 2010]), but probably because of more subtle factors, like the convergence of similar attitudes and behaviors shared among peers.

Clustering of obesity (yellow circles) in a social network (Christakis & Fowler, 2007)

To deny that environmental and social factors influence our biology, behavior, and attitudes is to negate the validity of whole swath of academia, not to mention common sense. We can see the import of social forces in multiple arenas in today’s world, from the way that opinion toward the ‘causes’ of homosexuality have shifted substantially over time, to the rising rates of unemployment, home foreclosures, and poverty in the current economic recession. In the eugenics movement in the early 1900s, there was a tendency to blame some intrinsic quality found within poor people  (genes, laziness) for their situation, which seems tantamount to blaming the kid in musical chairs who finds himself without a seat. Today, that opinion still exists, particularly out in pundit-land, but it is rightfully criticized for its callousness and ignorance. For example, after the Great Depression, blaming poverty on the impoverished became less prevalent as the formerly wealthy segments of society found themselves on hard times (Marks 1995: 90).

Changing views on ’causes’ of homosexuality (Gallup; May, 2010)

Ultimately, it’s a lot simpler (sometimes too simple) for people to judge others’ behaviors, not the myriad factors influencing those behaviors. When someone slips up, we fault them. And if someone hits a home run or wins a Nobel Prize, we congratulate them on their success, as we should. However, it would be more accurate, though obviously more cumbersome, to say “congratulations at finding yourself at the right confluence of genetics, environmental factors, and serendipity that facilitated the success of your efforts.”

Yeah, you can see why people don’t do that.


Bechara A, Damasio H, Tranel D, Damasio AR. 1997. Deciding advantageously before knowing the advantageous strategy. Science. 275(5304):1293-5. Link (abstract)

Brown PJ. 1992. The biocultural evolution of obesity: an anthropological view. In: Bjorntorp P, Brodoff BN (eds) Obesity. Philadelphia: JB Lippincott, pp. 320-9.

Christakis NA, Fowler JH, 2007. The spread of obesity in a large social network over 32 years. New England Journal of Medicine. 357:370-9. Full Ref

Gabbert C, Donohue M, Arnold J, Schwimmer JB. 2010. Adenovirus 36 and obesity in children and adolescents. Pediatrics. 126(4):721-6. Link

Marks J. 1995. Human Biodiversity. New Brunswick, NJ: Aldine Transaction. Link

Nesse R and Williams GC. 1995. Why We Get Sick: The New Science of Darwinian Medicine. New York: Times Books.

Schwartz MB, O’Neal Chambliss H,Brownell KD, Blair SN, Billington C. 2003. Weight bias among health professionals specializing in obesity. Obesity Research. 11(9): 1033-39 Full Ref

Wang Y,  Beydoun MA.2007. The Obesity Epidemic in the United States—Gender, Age, Socioeconomic, Racial/Ethnic, and Geographic Characteristics: A Systematic Review and Meta-Regression Analysis. Epidemiolic Reviews 29:6–28. Full Ref

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