The Columbian Exchange by John A. Tomaske, 1998
The Invasion
In the year 13-Flint (1492 AD by European reckoning) There was sickness,
hunger, a volcanic eruption and many beasts that devoured children in the Valley
of Mexico. This was an exception in what was a period of triumph for the Aztecs.
Lord Ahuitzotl, ruler of the Aztecs at the time, soon built a new aqueduct and
rebuilt and consecrated the great temple. A decade later, in the year 10-rabbit, his
successor Motecuhzoma (Montezuma) succeeded him as leader of the Aztecs.
There were rumors of strange hairy men in boats like small mountains. In the year
1-reed, the strange men came to stay.
These men had dogs larger than any ever seen and large man-animals that ran
faster than any man. These creatures divided and it became obvious that the
strangers had deer to carry them on their backs and these deer could be as tall as
the roof of a house.
Worst of all, as the Aztecs turned on the invaders, killing half of them, came a
hueyzahual that swept over the land. This pestilence spared the invaders but
covered with pustules, very many people died. A third - a half - the number is
unknown. On the day 1-serpent, in the year 3-house, the invaders and their Indian
allies defeated the Aztecs.
What the Spaniards Brought
New plants included wheat and other Eurasian grains; pear, peach, orange,
lemon tress; chick peas, grape vines, melons, onions, radishes and many plants
that became weeds.
They introduced wheeled vehicles - the Aztecs appear to have used wheels only
on toys. In their world, the only way to move goods overland was on the back of a
man. Messages moved by runner. Long distance running was, and in some cases
still is, a tradition among some Indian tribes.
They brought horses, pigs, sheep, goats, burros, and cattle.
Within a century, there were cattle everywhere. There were thousands upon
thousands of horses available to anyone with a few coins or the skill to rope them.
Legally, Indians were forbidden horses.
Most importantly, there were far fewer Indians. A century after the conquest, there
was perhaps one Indian for every ten or perhaps twenty who had been alive in the
Valley of Mexico a century earlier. War, brutality, hunger and social
disorganization took their toll. Disease was the single greatest cause of this
population decline.
Disease
The complete list of infectious diseases present in the Eastern Hemisphere but
not in the Americas in 1492 may never be known. However, most scholars believe
that the list should include: smallpox, measles, whooping cough, bubonic plague,
malaria, yellow fever, diphtheria, amoebic dysentery, and influenza. These were
diseases that spread most rapidly among dense populations, particularly, city
dwellers. In Europe, they were primarily diseases of childhood. Children who
survived had adapted to their environment and might live long and productive
lives. Those who did not, were quickly replaced by what was by modern
standards, a high birth rate. When these diseases struck a virgin population, the
death rates were sometimes not greatly different from those in the population at
risk in Europe - the children. That is, deaths might occur in as many as one-third
to one-half of the cases. Unfortunately, for Indian society, these death rates
accrued among the entire population!
Epidemics of these diseases swept over the Americas. About fifty epidemics
swept through the Valley of Mexico between 1519 and 1810. Brazil experienced
perhaps forty epidemics of smallpox before 1840. When De Soto led his
expedition through what is now the Southeastern United states, he found
evidence of the passage of epidemic disease. The Pilgrim settlements were
preceded by epidemics that may have killed ninety percent of the coastal Indian
population. Other epidemics had preceded the founding of Jamestown further
South.
Were there diseases that spread from the Americas to Europe? There is one
possible candidate - venereal syphilis. However, this issue is not settled.
American Food Crops in Europe, Asia and Africa
The greatest impact of America on Europe, Asia and Africa was the spread of
American food crops. This list includes: Maize, potatoes, sweet potatoes,
tomatoes, peanuts, manioc, caco, peppers, most beans, and squash. All of these
were unknown in the Eastern Hemisphere before 1492. In 1986, the maize and
potato harvest totaled 788 million metric tons. This was 78 percent of the 1,010
metric tons of wheat and rice harvested that same year.
The growth of population and industrialization in Northern Europe could not have
happened as they did without the increased nourishment provided by the potato.
Millions of Southern Europeans and African had their lives transformed by maize.
In the course of the eighteenth century, China more than doubled in population
due in considerable part to new American food crops.
Why these Crops were Adopted
At first glance, it is not obvious why European peasants would be interested in
these new crops. A peasant lives with little margin for error. A shift to a new crop
usually means taking land and other resources away from crops which the
peasant knows and which have allowed him and his family to survive. Why take
the risk? Rational peasants do not change crops unless there are substantial
rewards for doing so. The three triggers for the acceptance of these crops seem
to have been population growth, tax evasion and war.
Population growth creates a pool of underemployed labor that is available for
additional cultivation tasks. Moreover, peasants on the Northern European plain
extending from the North Sea coast to the Ural Mountains grew rye as their staple
grain. It would usually ripen in the short wet summers of the region. Potatoes will
do well in such a climate and will produce about four times the calories per acre
as rye. Better yet, potatoes could be planted in the fallow fields required for the
successful cultivation of rye. Potato production did not have to come at the
expense of rye production. Once this was figured out, the success of the potato
was assured.
A major reason for fallowing was weed control. The fallow fields were plowed
early enough in the year so that the weed seeds had sprouted but the weed
plants had not become mature enough to set seeds. Corn and potato production
required hoeing which had about the same effect on weeds as the fallowing
process. What was needed to make this system work was a bit more labor then
was required for rye production alone.
Potatoes had another advantage that actually initiated their acceptance as a
major food crop. Grain must be harvested and stored in a barn. This meant that it
was a convenient target for tax and rent collectors. The nobility ate the stuff. For a
long time the nobility were much less interested in the unfamiliar potato.
Moreover, plundering soldiers, living off of the land, found stored grain a
convenient source of food. Peasants dependant on gain could and often did
starve after an army went through their neighborhood. Potatoes could be left in
the ground or stored in small hordes through the winter. Soldiers didn't have time
to dig up a field of potatoes. Potatoes became an insurance against the all too
common disaster of war.
The disadvantage of depending on potatoes as a major food source is that they
do not last in storage as long as grain does. Carryover from one year to another is
impossible. Consequently, populations depending solely on the potato risk
disaster in case of crop failure. This was what occurred in Ireland in the 1840's.
Corn and most other American crops had a smaller advantage than did the potato
in Northern Europe. Corn requires longer and warmer summers then the potato.
Corn is a grain that had to be stored in barns so it was not the same kind of
disaster insurance that the potato was further North. Moreover, corn lacks certain
essential amino acids. A diet exclusively of corn will bring on a crippling disease
called pellagra. However, corn had a couple of advantages other than increased
caloric output per acre. Namely, landlords and city folk didn't want anything to do
with it. One could escape paying taxes in kind on maize fields. In the Balkans,
corn and beans (also from America) allowed villagers to live year around in the
mountains where they did not have to contend with two scourges of the plains malaria and Turkish oppression.
Tomatoes owed their acceptance to another source. They were known as "apples
of love' and were thought to stimulate sexual potency. In the vitamin deprived
world of pre-modern Europe, there may have been some small truth to this
reputation.