What do measles, tuberculosis, and grains have in common?

What do measles, tuberculosis, and grains have in common? For that matter, what do anthrax, influenza, and brucellosis also share in common with grains?

All the conditions listed are examples of , i.e., diseases contracted by humans from animals. When humans first invited domesticated grazing creatures - cows, sheep, goats - into our huts, adobe homes, or caves, often sleeping in the same room, using them for milk or food, we acquired many of their diseases. These diseases were essentially unknown prior to the human domestication of grazing ruminants.

The process of animal domestication changed the course of human civilization, providing a source of calories from their meat and organs, products made from the milk from their mammary glands, and led to the technology of fermentation, cheesemaking, and even to putting at least some of these animals to work as beasts of burden. And so did the acquisition of zoonoses from the same animals, such as the massive epidemics of tuberculosis that have plagued humans.

Grazing ruminants graze on grasses. Curiously, the human consumption of the seeds of grasses - i.e., "grains" - coincides with the domestication of grass-grazing ruminants. It is therefore tempting to speculate that the period of global climate change (increased temperature and dryness) recorded by geologists that caused a shortage of food for humans approximately 9000-12.000 years ago provided the motivation for hungry, desperate humans to observe the eating behavior of grass-grazing domesticated ruminants and ask, "Can we eat that, too?"

It is no small matter for humans to consume grasses. If it were einkorn wheat, the ancestor of all modern wheat, or teosinte, the ancestor of modern corn, for instance, try as we might, we cannot eat the roots, stalk, or leaves. Hungry, desperate humans figured out that, if we separated the seed from the husk, dried it, pulverized it (using stones), then added water and heated it, they could be consumed as porridge. Later, the Egyptians figured out that the pulverized seeds could be brewed into beer, or mixed with water and yeast (mixed with beer?) to make bread. They did not know, of course, that, despite being edible, the seeds of grasses remained largely indigestible - most of the proteins of grains cannot be digested by humans as we lack the enzymes to break apart the (proline-rich) amino acid sequences of proteins from grains. This explains why, for example, wheat germ agglutinin (in wheat, rye, barley, and a small quantity in rice) is 100% indigestible, passing from mouth, through the gastrointestinal tract, and out the anus untouched by human digestion (though doing plenty of damage in the process of coursing through, as well as the destruction wrought by the microgram quantities absorbed into the bloodstream). It also explains why the gliadin protein (of wheat, rye, barley, and probably the zein of corn) can remain intact and initiate the diseases of autoimmunity , such as rheumatoid arthritis and multiple sclerosis. (The indigestible proteins of the seeds of grasses provides the basis for many of the arguments made in my new book, .)

The domestication of ruminants therefore coincides with the effort to try to consume the seeds of grasses, both relatively recent developments in human adaptation on earth.

So much of the modern human dietary and health experience therefore relates to the act of domesticating grazing ruminants. Without them, human civilization would have taken an entirely different course with less successful population growth, less technological advancement (as Dr. Jared Diamond argues in ), fewer infectious disease epidemics. However, understand these anthropological and sociological issues and you are provided important insights into the human dietary and health experience. We can eat the organs and flesh of grazing ruminants as surrogates for wild game, but we should not sleep in the same rooms as they do. We most certainly cannot eat the same way they do, trying to survive on the products of grasses, AKA grains.

Ironically, the mistake we made all those thousands of years ago, a mistake certainly excusable given desperation, is now celebrated as the foundation of all modern dietary advice: "Eat more healthy whole grains." This is truly one of the biggest blunders ever made in diet and in health for us non-ruminants. We've largely conquered tuberculosis and measles, but we embrace the practice of consuming the seeds of grasses.