Darwinian Psychology-Part II: Why we eat junk

There’s no doubt about it, the average American diet is atrocious.  Give us the 44 ounce softdrinks, Big Macs, ice cream, and snack cakes, and we’ll take that every time over a healthy diet of fruit and vegetables.  Obesity is referred to as an “epidemic” in America.  I agree with all of that.[1]  Here’s where I get off of the bus:

Maybe your mother didn’t cry, “Mangia!” when you ate dinner, like mine did. Still, you’re likely to whisper it to yourself. That’s because you possess a simple survival impulse: Eat until sated. Our neanderthink legacy is to store as much energy as possible, since calories were scarce and uncertain for most of human evolutionary history and our metabolism was set to guard against the possibility of starvation tomorrow. The problem is that eating more doesn’t sate us; we merely recalibrate how much we think we need.

Our evolved mind-set on food hinders us in several ways. Our instincts tell us to keep eating well beyond when we are sated. Worse, the foods we crave—calorie-dense fats and sugars—were once rare and valued as a bulwark against starvation; now they’re plentiful and harmful in excess. We don’t crave plants, precisely because they were more abundant in our past. And if we do manage to temporarily gain a handle on the gustatory Disneyland in which we live, our dietary rigor plummets once we’ve lost weight.(1)

So, the notion is that our Neanderthink makes us do it.  For the sake of argument, let’s say I concede this point for a moment.  What is the recommendation?

We’re good at rationalizations to avoid governing our food intake. We tell ourselves, “I can get away with eating this delicious morsel,” or “It’s too hard to deny myself this scrumptious ice cream.” By yielding to such urges, we ratchet upward the amount of sugar and fat we crave, because we are tampering with a hormonal system finely attuned to the lack of such concentrated energy. On the savannah, the sweetest confection was wild fruit.

Michael Pollan, author of The Omnivore’s Dilemma, famously summed up what you need to know to consume healthfully: “Eat food. Not too much. Mostly plants.” The method by which we might hew to this Paleolithic regimen can also be summed up in seven words: “Dieting gets easier if you don’t cheat.”

So the question is, how do the recommendations actually follow from the just so story?  They don’t.  It’s just, “Don’t eat too much, and eat mostly plants.  Oh yeah, don’t cheat.”  But this goes back to the premise of my original post, and that is that the Darwinian Psychology narrative is thought to add scientific authority to whatever is being discussed.  Forget the fact that the conclusion does not follow from the premise in the article.  That is irrelevant to why these folks invoke a Darwinian just so story.  They think it adds credibility.  For me, they just prevented the story from being printed out and handed to my patients, which could have been beneficial.

The same periodical also published an article entitled, How to Be a Good Storyteller not long before.(2)

Perhaps they find these articles unrelated, but I found them to be very related:

Stories also entertain, educate, and instill moral values—sometimes all at once. We can all tell narratives, whether in the classroom, the boardroom, or the living room, but it takes practice to become a fine raconteur.

It seems the folks over at Psychology Today have been getting their practice.

(1) Neanderthink: An Outsize Appetite, Courtesy of Evolution, Nando Pelusi Ph.D., (11/17/08), Psychology Today
(2) How to Spin a Good Story, Brian Andrew, (10/20/08), Psychology Today

[1] I have a simple experiment which I use to teach my patients about their diet. This one has to do with sugar, and more specifically folks who are addicted to soft drinks. Go two weeks without any soft drinks (it actually doesn’t matter if it’s a diet soft drink or regular), and then go out and buy the biggest soft drink you can. Then it will be clear to you what it does to your mind and body. This is something that has worked in each case. In fact, the research shows that drinking just one diet soft drink daily increases the risk of being overweight to an extent that is greater than regular soft drinks, although not by much. One diet soft drink daily increases your chances by approximately 42% whereas one sugar filled drink increases your chances by 38%. It goes up with each additional drink per day.


6 Responses

  1. Thanks for mentioning my article. I respectfully submit to you that the conclusions follow, because it addresses WHY we eat too much. I may be wrong, but WHY is it easy to eat fats and sugar, and hard to stay slim? Could it be that the modern environment differs from our scarcer ancient one? We agree that as humans we have flaws in eating choices, but we mght offer other explanations.
    Nando Pelusi

  2. Nando,

    Thank you for responding. I’ll tell you why. You ignore cultural, economic, and personal factors in the reasons for why this could occur. You also take a position that opposes the largest portion of the population by advocating a position that many see as incompatible with their theological perspective.

    I explain to patients, who are believers (at least 95% of my patients), that God created us with a desire for those things that are sweet. In the Garden of Eden, that was fruit. It was only in recent history that refined sugar became extremely plentiful. Refined sugar is the result of a process that removes all the beneficial vitamins and nutrients that we were created to seek out because of the health benefits of those foods that are naturally sweet. In the Garden, fruits and vegetables were the ONLY diet. Just as you, I have no way of proving these assertions.

    If you examine some cross cultural variables, you will find that culture plays a role. Our economic system, I think also plays a role. And from the patients that I have worked with, individual factors play, in my opinion, the most important role. So, to invoke a Darwinian explanation, you invoke an explanation that can have no empirical support. It might appeal to a tiny portion of the population, but I would suggest that in the future, you give advice without the Darwinian component. Then, maybe it would be something I would feel comfortable in printing out and handing to my patients.

    Now, I can never know with 100% certainty that you are incorrect in your story. It could be that I am completely wrong and you are correct. But if you want to help people, and I think you do, leave Darwin out of it. Anyway, I’m a shrink who works in the sticks, and maybe you work with a different population. But the way you wrote about this won’t fly out here. But again, I thank you for responding, and I hope you don’t find my strong criticism too offensive.

  3. Thanks for your candor. Perhaps we can peaceably disagree, because great explanatory power is afforded by the darwinian paradigm across so many fields, and my column Neanderthink looks for that dimension of understanding. That’s not to negate any particular religious view, since darwinism says nothing against religion, it just predicts what to expect in a modern world, mismatch from Eden (or the Savanna).

    Evolutionary psychology gets attacked from the Left (Marxists like SJ Gould and his followers for being Just So Stories) because of a misunderstanding that genes determine us — which we know to be false. But also attacked from the Right (Religious people who believe it undermines faith). Both are mistaken, in my view.

    Meanwhile, we both have our work cut out for us in understanding why so many intelligent people keep acting (and feeling) so self-defeatingly!


  4. Perhaps we can peaceably disagree, because great explanatory power is afforded by the darwinian paradigm across so many fields, and my column Neanderthink looks for that dimension of understanding.

    I agree with the first part of your sentence, but not the second. 😉 It’s little more than imagination packaged as science.

    Evolutionary psychology gets attacked from the Left (Marxists like SJ Gould and his followers for being Just So Stories) because of a misunderstanding that genes determine us — which we know to be false. But also attacked from the Right (Religious people who believe it undermines faith). Both are mistaken, in my view.

    So, I guess I have attacked it from both the left and the right.

    On the one hand, by making a Darwinian explanation you are making a genetic inference. On the other hand, Darwinian explanations have been given all along the way to explain away faith (e.g., Freud, Dawkins, and a host of others).

  5. “Dieting gets easier if you don’t cheat.”

    I am 58 years old and have been obese since I was 6 years old. I spent the first thirty or more years of my life dieting and reading the “experts” (who, BTW, were all skinny) and never maintaining a weight loss for more than 6 months. My mother and her mother were “morbidly” obese, as I am now, and struggled as I still do.

    The quote above, in my experience, is not true in any way! Oh, for sure, this may work for a skinny neurotic who gets paranoid when they gain five pounds, but for a person who is looking to lose 100 or 200 pounds, this is just another ridiculous statement like “Just Say No” and “No Child Left Behind!”

    A wise man (unlike most men and women, today) once said,

    But have nothing to do with worldly fables fit only for old women. On the other hand, discipline yourself for the purpose of godliness; 8 for bodily discipline (or weight loss or exercise) is only of little profit, but godliness is profitable for all things, since it holds promise for the present life and also for the life to come. 9 It is a trustworthy statement deserving full acceptance. (1 Timothy 4: 7-9)

  6. Great points DB. A one size fits all approach to psychology makes for horrible practice. For some folks the complexity of losing weight cannot be addressed by all the diet books in the world. I had one patient donate all his diet books to a local library, and he burned the rest. His life improved after that. I think folks don’t often realize just how difficult this issue can be, and resorting to silly Darwinian just so stories will not help anyone. But the profit of having God in your life is genuine and enduring.

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