134 DESTINY DISRUPTED
dawn to dark just to scratch up enough food to keep from starving and
support a thin upper class of military aristocrats and clerics (and since cler-
ics couldn't marry, their ranks were replenished largely out of the military
aristocracy.) Except for those few who went into the church, upper-class
boys studied hardly anything except how to fight.
Sometime in the eleventh century, however, the consequences of vari-
ous tiny technological innovations accumulated to a tipping point. These
innovations were so subtle that they probably went all but unnoticed at the
time. One was a modified, steel-tipped "heavy" plow that could cut
through roots and, compared to the older models, dig a deeper furrow in
the dense, wet soil of northern Europe. The heavy plow enabled peasants
to clear forests and extend their fields into areas previously considered un-
suitable for farming. In effect, it gave peasants more land.
A second invention was the horse collar, which was just a slight im-
provement of the yoke used to harness a beast of burden to a plow. The
earlier version could be used only with oxen, due to its shape. If a horse
were strapped to that yoke, the strap would press against the horse's neck
and choke off its air supply. At some point, some unknown innovator
modified that yoke just enough to have it press against a horse's shoulders
and a lower spot on its neck. With this yoke, peasants could use horses in-
stead of oxen to plow their fields, and since horses plow about fifty percent
faster than oxen, they could till more land in the same amount of time.
A third innovation was three-field crop rotation. Farming the same plot
of land year after year exhausts the soil, so farmers have to let their fields
"rest" from time to time. But the stomach never rests, so European peas-
ants customarily divided their land into two fields. Each year they planted
crops in one field and let the other field lie fallow. The next year, they
planted crops in the second field and let the first lie fallow.
Over the centuries, however, Europeans came to realize that a field
didn't have to rest every second year. It stayed just as fertile if it lay fallow
one year out of three. Gradually, peasants started dividing their land into
three plots, and planting two of them each year while letting one lie fallow.
In effect, this gave peasants one-sixth more arable land each year.
What did these little changes add up to? Not much. They merely al-
lowed peasants to produce a slight surplus from time to time. When they
had a surplus, they took it to certain crossroads on designated days and