In my grad program, we’ve spent a lot of time talking about Paul Ehrlich and John Holdren’s IPAT equation. It’s pretty simple:
Impact = Population x Environment
English translation: A society’s environmental impact is proportional to its population, its wealth, and its technological capacity to mitigate the impacts of its population and its wealth.
So how do you reduce impact? Well, it’s too ethically and politically dicey to do a whole lot about population — at least beyond educating women. Affluence? Let’s put it this way: How would you like to be the one to tell El Salvador or Namibia to stay poor because the world has all the rich countries it can take?
That leaves technology, the only spot where conventional wisdom tells us we have a little wiggle room. Humans have proven their ingenuity time and time again, after all. And since we seem to be pretty powerless over population and wealth, we have no other choice but to hope that the technological breakthroughs of the future will help dig us out of the environmental messes of today.
Trouble is, many of these messes were caused by the technological innovations of past. Electricity, the automobile, the airplane, chemical pesticides … the list goes on. None of these technologies are inherently bad. In fact, on a surface level, many do a lot of good. But unfortunately they’ve all had unintentional — and often negative — environmental consequences.
That’s because, as Westerners, we tend to think of ourselves as apart from the world at large. Man vs. Nature, never Man in Nature. We study ecosystems, we aren’t a part of any. But as climate change is making abundantly clear, we are part of a system — a big part. And every time we alter one part of the system without considering what it will do to rest, we’d better be prepared for our actions to come back to bite us in the you-know-what.
That brings me to the inspiration for today’s little diatribe — Michael Pollan’s cover story on food science in the New York Times Magazine. It turns out that taking a bunch of supplements — or noshing on nutrient-enriched processed foods — just ain’t the same as eating a good old fashioned salad.
Most nutritional science involves studying one nutrient at a time, an approach that even nutritionists who do it will tell you is deeply flawed. “The problem with nutrient-by-nutrient nutrition science,” points out Marion Nestle, the New York University nutritionist, “is that it takes the nutrient out of the context of food, the food out of the context of diet and the diet out of the context of lifestyle.” If nutritional scientists know this, why do they do it anyway? Because a nutrient bias is built into the way science is done: scientists need individual variables they can isolate. Yet even the simplest food is a hopelessly complex thing to study, a virtual wilderness of chemical compounds, many of which exist in complex and dynamic relation to one another, and all of which together are in the process of changing from one state to another. So if you’re a nutritional scientist, you do the only thing you can do, given the tools at your disposal: break the thing down into its component parts and study those one by one, even if that means ignoring complex interactions and contexts, as well as the fact that the whole may be more than, or just different from, the sum of its parts. This is what we mean by reductionist science.
Scientific reductionism is an undeniably powerful tool, but it can mislead us too, especially when applied to something as complex as, on the one side, a food, and on the other, a human eater. It encourages us to take a mechanistic view of that transaction: put in this nutrient; get out that physiological result. Yet people differ in important ways. Some populations can metabolize sugars better than others; depending on your evolutionary heritage, you may or may not be able to digest the lactose in milk. The specific ecology of your intestines helps determine how efficiently you digest what you eat, so that the same input of 100 calories may yield more or less energy depending on the proportion of Firmicutes and Bacteroidetes living in your gut. There is nothing very machinelike about the human eater, and so to think of food as simply fuel is wrong.
Also, people don’t eat nutrients, they eat foods, and foods can behave very differently than the nutrients they contain. Researchers have long believed, based on epidemiological comparisons of different populations, that a diet high in fruits and vegetables confers some protection against cancer. So naturally they ask, What nutrients in those plant foods are responsible for that effect? One hypothesis is that the antioxidants in fresh produce — compounds like beta carotene, lycopene, vitamin E, etc. — are the X factor. It makes good sense: these molecules (which plants produce to protect themselves from the highly reactive oxygen atoms produced in photosynthesis) vanquish the free radicals in our bodies, which can damage DNA and initiate cancers. At least that’s how it seems to work in the test tube. Yet as soon as you remove these useful molecules from the context of the whole foods they’re found in, as we’ve done in creating antioxidant supplements, they don’t work at all. Indeed, in the case of beta carotene ingested as a supplement, scientists have discovered that it actually increases the risk of certain cancers. Big oops.
Big oops, indeed. We seem to be remarkably proficient at big oopses. And unless we stop innovating in a bubble, we’re going to keep being good at them. Lord help us if there ever comes a day when we start having to engineer “water equivalents” and “old-growth-forest” serenity pills.
