In a recent post, I said a well-functioning system will produce both optimality and complexity. I meant important systems like our bodies, economies, and formal education. If you look at the nutrition advice provided by the United States Department of Agriculture — the food pyramid, the food plate, the recommended daily allowances, and the associated reports — you will find nothing that increases the complexity of metabolism inside our bodies (in particular, the diversity of metabolic pathways). The advice is all optimality — for example, the best amounts of various micronutrients. The people behind the USDA advice, reflecting the thinking of the best nutrition scientists in the world, utterly fail to grasp the importance of complexity. Half of nutrition research — or more than half, since the topic has been so neglected — should be about how to increase internal complexity. In practice, almost none of it is. It’s obvious, I think, that the microbes within us are very important for health. They are mostly in our intestines and must be heavily influenced by what we eat. How did they get there? How can their number be increased? How can their diversity be increased?
The absence is especially striking because the point is so simple. To solve actual problems, you need both optimality and complexity. Showers — what we use to take a shower — provide an example. You want to adjust the water temperature. If you try to do this while taking a shower, it can be hard because of the delay between changing the hot/cold water proportions and feeling the effects. It is better to use the bathtub (lower) tap to set the temperature (measuring it with your wrist) and only after you’ve optimized the temperature, shift the water to the shower head. The bathtub tap produces simple output (a single stream of water) that is easy to optimize. The shower head produces more complex output that is harder to optimize but does a better job of washing (an actual problem). You need both bathtub tap (for optimization) and shower head (for complexity) to do a good job solving the problem. Likewise, we need both an understanding of necessary nutrients (Vitamin A, etc.), which can be optimized, and an understanding of microbes, which cannot be optimized but can be made more complex, to make good decisions about what food to eat. Ordinary food is the hardware, you might say; and microbes are the software.