“Wherever the European has trod, death seems to pursue the aboriginal.”

-Charles Darwin, 1836⁷⁷³

Guns, Germs and Steel

UCLA professor Jared Diamond explored how pivotal the domestication of farm animals was in the course of human history and medicine in his Pulitzer Prize-winning book Guns, Germs, and Steel. In the chapter “Lethal Gift of Livestock,” he argues convincingly that the diseases we contracted through the domestication of animals may have been critical for the European conquest of the Americas in which as many as 95% of the natives were decimated by plagues the Europeans brought with them. Natives had no prior exposure or immunity to diseases like tuberculosis, smallpox, and measles. Parallels were seen throughout the world with single missionaries unintentionally exterminating the entire target of their religious zeal with one of livestock’s “lethal gifts.”⁷⁷⁴

Why didn’t the reverse happen? Why didn’t Native American diseases wipe out the landing Europeans? Because there essentially weren’t any epidemic diseases. Medical historians have long conjectured that the reason there were so many plagues in Eurasia was that “crowd” diseases required large, densely-populated cities, unlike the presumed small tribal bands of the Americas. But that presumption turned out to be wrong. “New world” cities like Tenochtitlan were among the most populous in the world.⁷⁷⁵

The reason the plagues never touched the Americas is that there were far fewer domesticated herd animals. There were buffalo, but no domesticated buffalo, so there was presumably no opportunity for measles to arise. No pigs, so no pertussis; no chickens, so no Typhoid Marys. While people died by the millions of killer scourges like tuberculosis in Europe, none were dying in the “new world” because no animals like goats existed to domesticate. The last ice age killed off most of the easily domesticated species in the western hemisphere, such as American camels and horses, leaving the indigenous population only animals like llamas and guinea pigs to raise for slaughter, neither of whom seem to carry much potential for epidemic human disease.⁷⁷⁶