In Defense of Food and creationism

On a recent flight I was finally able to digest (ha!) Michael Pollan’s In Defense of Food.  The first part of the book is a historical narrative of the science, policy, and politics of nutritionism in the US.  In Part I, Pollan mounts a devastating critique of US nutritional science and policy. The climax is Chapter 5, “The Melting of the Lipid Hypothesis”, which is perhaps the most important bit of science writing I’ve read all year.    I was left wondering why anyone ever listens to nutritionists.  The only (and minor) weak point in Part I is the tendency to make the nutritionists’ blunders and the grain industry’s lobbying seem more like a nefarious, well-coordinated conspiracy.

But in the Part III of the book, now that Pollan has knocked the scientific wisdom of the day off its altar, it’s time for him to offer an alternative.  And what he proposes isn’t too convincing.  One problem is that Pollan spends so little effort convincing us that there is any sound scientific basis to his recommendations.  In Part I of the book, Pollan adeptly compares case-control studies, cohort studies, and intervention trials…but the entire scientific basis for Pollan’s recommendations on how to eat in Part III appears to be this passage (note the classic correlation-is-not-causation mistake):

People eating a Western diet are prone to a complex of chronic diseases that seldom strike people eating more traditional diets.  Scientists can argue all they want about the biological mechanisms behind this phenomenon, but whichever it is, the solution to the problem would appear to remain very much the same: Stop eating a Western diet.

Instead of science, Pollan’s recommendations rest on cultural traditions.  “Don’t eat anything your grandmother wouldn’t recognize as food,” he says on pg. 148.  “Cultures have had a great deal to say about what and how and why and when and how much we should eat,” says pg. 133.

This train of thought sounds like some creationists’: Both Pollan and creationists poke holes in the scientific orthodoxy and would have us insert tradition in its place. Similarly, creationists think that atheists plot to discredit their work; Pollan warns us to resist the pernicious myths propagated by the “Nutritionalist Industrial Complex”.

The analogy between creationists and In Defense of Food only goes so far, of course.  Most importantly, creationists are not nearly as persuasive in their efforts to poke holes in the scientific orthodoxy. And, even if creationists are wrong, Pollan might still be right. Personally, as weak as I find In Defense of Food’s scientific basis, I think Pollan might be on to something – and I can’t say the same for creationists.

What I’m reading

What I’m reading:

1. The Chemical Tree: A History of Chemistry by William H. Brock. A impressive amount of chemistry, from alchemy to Boyle to Bosch, crammed into a single book. Reading this makes me appreciate just how often and how badly the greats were flat-out wrong about chemistry.
2. Plows, Plagues, and Petroleum by William F. Ruddiman. The first part of this book distills down what I think is a mainstream view of climatology in a highly readable way. The second part, which I haven’t gotten to yet, seems to be controversial, at least as judged from amazon reviews.

Brain Rules vs. 10,000 Year Explosion

These two books fell into my hands at the same time. Reading them concurrently was quite interesting.  They paint starkly contrasting pictures of the human brain.

Brain Rules (pgs. 4-5) says the brain’s formative period, evolutionarily speaking, was on the Serengeti:

The brain appears to be designed to solve problems related to surviving in an unstable outdoor environment, and to do so in nearly constant motion.

10kYE (pgs. 74-75), in contrast, says:

Many [alleles] are very recent: the rate of origination appears at about 5,000 years ago in the European and Chinese samples, and at about 8,500 years ago in the African sample. [...]  Many involve changes in metabolism and digestion, in defenses against infectious disease, in reproduction, in DNA repair, or in the central nervous system [emphasis mine - CF].

10kYE (pg. 98) later elaborates on this idea:

The most interesting kind of genetic changes are those that affect human personality and cognition, and the evidence is good that such changes have indeed occurred. [...] Several of the new alleles have effects on serotonin, a neurotransmitter involved in the regulation of mood and emotion. [...] And there are new versions of genes that play a role in brain development: genes that affect axon growth, synapse formation, formation of the layers of the cerebral cortex, and overall brain growth.

Brain Rules (pg. 81) says “Universally experienced stimuli…follow strict Darwinian lines of threats and energy resources.”

10kYE (pg. 112) says:

The polymorphism [the7R allele of the DRD4 {Dopamine Receptor D4} gene, associated with Attention-Deficit/Hyperactivity Disorder] is found at varying but significant levels in many parts of the world, but is almost totally absent from East Asia….It is possible that individuals bearing these alleles were selected against because of cultural patterns in China.

Brain Rules (pg. 10) describes our evolutionary history this way:

When our bountiful rain forests began to shrink, collapsing the local food supply, we were forced to wander around an increasingly dry landscape looking for more trees we could scamper up to dine.  As the climate got more arid, these wet botanical vending machines disappeared altogether.  Instead of moving up and down complex arboreal environments in three dimensions, which required a lot of dexterity, we began walking back and forth across arid savannahs in two dimensions, which required a lot of stamina.

10kYE devotes an entire chapter, titled “Medieval evolution: How the Ashkenazi Jews Got Their Smarts”, to informed speculation that Ashkenazi Jewish brains have profoundly evolved in the last 1000 years.

Our brains’ evolution either stopped when we were hunter-gatherers and has had no time to adapt to the hugely different set of risks and stimuli provided by modern society, or it didn’t.  Cochran and Harpending admit some of their specific examples are speculative and unproven, but in general, they are solidly convinced that humans and human nervous systems have been evolving rapidly in the last 10,000 years. In contrast, Brain Rules is rooted to the idea that the cubicles of our modern workplace or the desks of our modern class rooms are “anti-brain”, because our brain evolved in hunter-gatherers who lived in open grasslands. The tension between these two core ideas seems inescapable.

I am no neuroscientist; I am just an outsider looking in. But my sense is that Harpending and Cochran are challenging neuroscience orthodoxy, and that Medina’s book is, scientifically, a distillation of current mainstream thought. It will be interesting to see how well the ideas of Cochran and Harpending catch on in coming years.

What I read

1. 10,000 Year Explosion by Greg Cochran and Henry Harpending.  People are still evolving!
2. The Honest Broker by Roger Pielke, Jr.  If, like me, you’re a scientist or engineer, and you have never read a political science book, this book may bring a few revelations.
3. Brain Rules by John Medina.  An intro to brain neurobiology, purporting to be a business book.  Or maybe vice versa, I can’t really tell.
4. Echoes of Life by Susan M. Gaines, GeoffreyEglinton, and Jurgen Rullkotter.  A fascinating and thorough, if a bit self-indulgent, history of biomarkers and geobiology.