Last month, I explained Why Paleo Is the Healthiest Diet Possible. One of the underlying topics I covered was the role of natural selection in human evolution.

I think that understanding human evolution is the single most important step to understanding nutrition.

Here’s the thing. As I said last time, people misunderstand or reject evolution more often than not. While reading one reader’s comment on that post, I cringed:

Evolution is a response to the idea that adaptation will either kill us or make us better/fitter/more adapted. So, by eating grains, potatoes, and yes, even milk, I’m ensuring that my children can digest a wider range of foods than my ancestors could.

Wow! I don’t think it works quite that way. I felt that this reader was misguided, but understandably so. There is such a strong anti-evolution, even an anti-science, bias in this country that it’s amazing anyone learns anything about it at all.

I hope I don’t come across as a jerk for this post. I’m not an expert and I won’t pretend to be one. I just want to share my own understanding of natural selection.

I wrote a quick and dirty genetic algorithm. Genetic algorithms are specialized computer programs that mimic real evolutionary mechanisms to solve problems. Therefore, they’re a good way to show how natural selection works. My genetic algorithm attempts to simulate a small population (20) of organisms of the same species. Here’s how it works:

  • Each organism is represented by one trait. In this case, it’s simply a number, 0-99. You could think of this trait as the length of a dog’s fur, the size of a bird’s beak, or the color of an animal’s skin.
  • The first twenty organisms are randomly assigned their traits.
  • After each generation, the five organisms that are most adapted are “selected”, meaning they will each have 4 offspring. The other 75% quietly die off.
  • What does most adapted mean? In this case, I arbitrarily chose “most adapted” to mean numbers closest to the number 42. Once again, you could think of the number representing the color of an animal and perhaps 42 is the color that blends in best with the surrounding environment and thus offers improved survival rates.
  • Each offspring will have randomly mutated (changed by -2,-1, 0, 1, 2) from its parent.

This is a dynamic script by the way. The starting conditions are random. The mutations are random. Refresh it to see if anything changes! What you’ll see over and over is that the final generation is very well adapted (close to 42). These organisms don’t “know” how to adapt. All they do is mutate randomly, sometimes closer and sometimes away from full adaptation. Yet, because resources are limited, only the most adapted organisms get to reproduce. It works over and over again. I would say that it has to work.

Now let’s try something different. What if we were to be very nice to these organisms? Instead of only 25% getting to reproduce, every single organism will get to have one offspring and no one will miss out. Essentially, we are removing the “selection” part of natural selection. Everybody is a winner!

The results? Some of our organisms might be close to 42, but most of them probably are not close at all. What if 42 represented full adaptation to consuming dairy products? If you had a trait of 42, you could fully utilize all the nutrients in dairy, drink as much milk as you would like without side effects, and be able process dairy perfectly. Flip that around and think about being a 70. You would have a hard time absorbing the available nutrients in dairy, a difficulty in stomaching large amounts of milk, and of course a plethora of unwanted side effects from ingesting it (stomach cramps, bloating, flatulence and diarrhea).

My argument is that our species is now closer to the second algorithm. The natural selection has been removed almost completely. How did it get removed? Modern medicine, shelter, and agriculture. Almost everyone is kept alive because we have the technology to do so. And rightfully so; I’m not suggesting eugenics. What I am saying is that we just haven’t had a chance to adapt to modern foods.

Please realize that this is a very simplified take on natural selection. Natural selection is very slow, each organism has thousands of different traits that can be selected for, not all reproduction is asexual, and it’s not always the most adapted organisms that survive. I still think, however, that it illustrates the point: natural selection makes a species well adapted to its environment over time. Take out the natural selection and the species is terribly maladapted. This has some very serious implications for us as humans.

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