Book Report: 1493: Malaria and Potatoes

The consequences of the Columbian Exchange.

1493 explores the consequences of the Columbian Exchange.

I found two parts of the story particularly interesting:

  • the impact of malaria on slavery in the American South
  • how critical the potato became to Europe


Malaria was a defining influence in the American South. Smallpox and influenza epidemics passed through and moved on. Malaria became an endemic part of life that caused death and debilitation year after year.

Why slaves from Africa instead of American Indians or indentured servants from Europe? One reason is that slaves from Africa lived longer. Malaria came to the Americas from central and western Africa. Genetic mutations made people from malaria’s native range resistant in ways Europeans and American Indians were not.

Malaria immunity was not absolute. Larger plantations with more slaves could tolerate more malaria-related deaths or incapacitations, and so accrued an advantage over smaller operations. This led to fewer, larger plantations.

Why did the Mason-Dixon line become the boundary between free and slave states? The line was drawn between Maryland and Pennsylvania to resolve a border dispute. Maryland later stayed a slave state; Pennsylvania did not. One reason for the two different paths may have been malaria: Pennsylvania is too cold. African’s malaria resistance did not provide a survival advantage further north.

During the Revolutionary War and the Civil War, malaria debilitated invading armies. 1493 reports that in the year after Bull Run / Manassas, more than a third of the invading Union army suffered from malaria.


Potatoes were key to breaking cycles of famine in northern Europe.

Even prosperous cities like Florence had about seven bad harvests for every good one. A field of potatoes yielded 20x the food as a field of wheat or barley. Potatoes were ready in the lean summer months before the fall harvest refilled granaries and before an early winter could ruin crops. Passing armies could not easily take potatoes left in the ground.

Could people live on potatoes? Ireland is the extreme example. 1493 reports that about 40% of the population subsisted primarily on potatoes. An average Irish laborer ate twelve and a half pounds daily - about twenty-five medium-sized potatoes. With milk, potatoes provide all the nutrients a human needs.

How successful were potatoes? By the 1960s, Ireland’s population was only half of what it was before the 1840s potato famine.


I wish this was the kind of history taught in my schools: rather than people and ideas, focus on the larger forces that shape behavior.

These kinds of stories reinforce my impatience with the anti-science movement in the US - in particular, denying climate change or denouncing vaccines. In addition to malaria and potatoes, the book talks about yellow fever, insect blights, and more. Civilizations were leveled because they could not understand or avoid the cause of their destruction. We know what to do.