The Knowledge: How to Rebuild Our World From Scratch (41 page)

*
However, some of the longer-term ramifications of the Black Death were beneficial to society: a cultural silver lining to the cloud that was the Great Dying. With the ensuing labor shortage, serf peasants surviving the mass depopulation were able to slip their bond to the lord of the manor, helping break the oppressive feudal system and usher in a much more egalitarian social structure and market-orientated economy.

*
Although only those for correcting farsightedness: the concave lenses for nearsightedness, which affects most people, disperse the light rays rather than focusing them. William Golding famously made this mistake in
Lord of the Flies
, with the nearsighted Piggy using his spectacles to start fires.

*
Also, modern packaging and articles are rarely formed from a single plastic type. For example, a toothpaste tube is actually composed of five layers, all extruded at the same time: linear low-density polyethylene, modified low-density polyethylene, ethyl vinyl alcohol, modified low-density polyethylene, and finally linear low-density polyethylene (fittingly, the plastic tube is itself extruded out of a nozzle, much like the toothpaste it will be filled with). This makes the plastic of many products practically unrecoverable, and so only simple articles, such as a PET clear water bottle, would be worth salvaging in a post-apocalyptic world.

*
Even the familiar color of carrots is artificial: their roots are naturally white or purple, and the orange variety was created by seventeenth-century agriculturists in the Netherlands to honor William I, the Prince of Orange.

*
Even within Britain, the Norfolk four-course rotation is less effective on the heavy clay soils of the north and west, and so historically these regions focused on livestock pasturing and on manufacturing (and using their profits to buy grain from the south).

*
Using many of the advances discussed in this chapter, between the sixteenth and nineteenth centuries the British agricultural revolution achieved a substantially greater production of food while simultaneously becoming less labor-intensive, and the fact that a decreasing proportion of farmers and agricultural laborers was needed to feed everyone else enabled greater urbanization. By 1850, Britain had the lowest proportion of farmers of any country in the world, with only one person in five working the fields to feed the entire nation. By 1880 only one Briton in seven had to work the land, and by 1910 that had fallen to one in eleven. And in developed nations today, which exploit artificial fertilizers, pesticides, and herbicides, as well as enormously labor-efficient technologies like combine harvesters, every agricultural worker grows enough food to feed around fifty others.

*
Vestiges of the historical importance of salt remain in our language today. Roman soldiers, for instance, were given an allowance to buy salt, which is the derivation of the word “salary.”

*
One exception is the preparation of corn used traditionally by the native cultures of Mesoamerica. Here the corn is boiled in an alkaline solution, from either slaked lime or ashes thrown into the water, to “nixtamalize” it (from the Nahuatl words for ashes and corn dough). Not only does this improve the flavor, it also makes the crop’s vitamin B3 available for absorption by the body. The disease pellagra, caused by deficiency of this vitamin, plagued Europeans and North Americans relying on a staple of corn for two centuries, because they adopted the crop but not the proper technique of preparing the grain for consumption.

*
The landmasses in the northern hemisphere extend much closer to the pole than in the southern hemisphere—Newcastle, Moscow, and Edmonton are far closer to the pole, and so receive less winter light, than anywhere on the southern continents of Africa, Australia, or South America.

*
And more than six thousand years ago South American inhabitants discovered how to explosively evert the kernels of particular varieties—now the basis of a billion-dollar cinema-focused market in the US alone.

*
The first can openers did not appear until the 1860s, fifty years after the French army began issuing canned food. Soldiers were expected to open their rations with a chisel, or their bayonet, and it was only once cans became widespread among the civilian population that the opener was needed.