At Home - Bill Bryson [20]
What killed the Orcadians was not dietary deficiency but disease. People living together are vastly more likely to spread illness from household to household, and the close exposure to animals through domestication meant that flu (from pigs or fowl), smallpox and measles (from cows and sheep), and anthrax (from horses and goats, among others) could become part of the human condition, too. As far as we can tell, virtually all of the infectious diseases have become endemic only since people took to living together. Settling down also brought a huge increase in “human commensals”—mice, rats, and other creatures that live with and off us—and these all too often acted as disease vectors.
So sedentism meant poorer diets, more illness, lots of toothache and gum disease, and earlier deaths. What is truly extraordinary is that these are all still factors in our lives today. Out of the thirty thousand types of edible plants thought to exist on Earth, just eleven—corn, rice, wheat, potatoes, cassava, sorghum, millet, beans, barley, rye, and oats—account for 93 percent of all that humans eat, and every one of them was first cultivated by our Neolithic ancestors. Exactly the same is true of husbandry. The animals we raise for food today are eaten not because they are notably delectable or nutritious or a pleasure to be around, but because they were the ones first domesticated in the Stone Age.
We are, in the most fundamental way, Stone Age people ourselves. From a dietary point of view, the Neolithic period is still with us. We may sprinkle our dishes with bay leaves and chopped fennel, but underneath it all is Stone Age food. And when we get sick, it is Stone Age diseases we suffer.
II
If, ten thousand years ago, you had been asked to guess which area of the world would be the seat of the greatest future civilizations, you would probably have settled on some part of Central or South America on the basis of the amazing things they were doing with food there. Academics call this portion of the New World Mesoamerica, an accommodatingly vague term that could fairly be defined as Central America plus as much or as little of North and South America as are needed to support a hypothesis.
Mesoamericans were the greatest cultivators in history, but of all their many horticultural innovations none was more lastingly important or unexpected than the creation of maize, or corn as it is known where I come from.* We still don’t have any idea how they did it. If you look at primitive forms of barley, rice, or wheat set beside their modern counterparts, you can see the affinities at once. But nothing in the wild remotely resembles modern corn. Genetically, its nearest relative is a wispy grass called teosinte, but beyond the level of chromosomes there is no discernible kinship. Corn grows into a hefty cob on a single stalk and its grains are encased in a stiff, protective husk. An ear of teosinte, in comparison, is less than an inch long, has no husk, and grows on a multiplicity of stems. Teosinte is almost valueless as a food; one kernel of corn is more nutritious than a whole ear of teosinte.
It is beyond us to divine how any people could have bred cobs of corn from such a thin and unpropitious plant—or even thought to try. Hoping to settle the matter once and for all, food scientists from around the world convened in 1969 at a conference on the origin of corn at the University of Illinois, but the debates grew so vituperative and bitter, and at times so personal, that the conference broke up in confusion and no papers from it were ever published. Nothing like it has been attempted since. Scientists are now pretty sure, however, that corn was first domesticated on the plains of western Mexico, and are in no doubt, thanks to the persuasive wonders of genetics, that somehow