It wasn’t as if Thomas Jefferson didn’t have more pressing matters to attend to. He was governor of Virginia, then minister plenipotentiary to France. And, oh yes, there was the matter of writing the Declaration of Independence. Despite all these responsibilities, for more than a decade Jefferson was obsessed with a nasty theory of natural history coming out of the salons of Europe. He took it upon himself to correct the scientific record and fight a slander against his country—a slander that had political, philosophical, and economic consequences. Jefferson, the great polymath, didn’t fully realize what he was getting himself into; the ugly theory he was set on dismantling would engage many of the world’s finest minds long past his own death in 1826.
The trouble started with Count George-Louis Leclerc Buffon, curator of the King’s Natural History Cabinet in France and arguably the most famous scientist on the planet in 1749, when he began publishing volumes of what would become a 6,000-page encyclopedia of natural history called Histoire Naturelle. In it, he proposed what became known as Buffon’s theory of New World degeneracy. Buffon argued that because North America was a cold and wet clime, all species found there were weak, shriveled, and diminished—they were degenerate.
Buffon proclaimed that North America was a land of swamps, where life putrefied and rotted. Try to raise domesticated species—cattle, pigs, sheep, goats,whatever—in this place, Buffon proclaimed, and they, too, would degenerate, producing lines of puny, feeble offspring. Buffon claimed to see the effects of degeneracy on the indigenous people of the New World. Native Americans, Buffon wrote, were stupid, lazy savages who degenerated for the same reason that animals did—the cold and humidity. To add to the insult, the count argued that by failing to drain the swamps, Native Americans were responsible for promoting the wet climate that led to degeneration in the first place.
Today, we read Buffon’s ideas as absurd and offensive, but they caught on like wildfire, providing Europeans with a handy scientific justification for believing that their continent was superior to this New World that they felt threatened by. Histoire Naturelle was translated into a slew of languages, including German, Dutch, and English, and it was the talk of the salons. Soon others were parroting and expanding Buffon’s theory of New World degeneracy.
The French Abbé Guillaume-Thomas Raynal and the Dutch Abbé Cornelius De Pauw worshipped Buffon’s theory but thought it did not go far enough. They each wrote book-length treatises outlining how Europeans silly enough to move to America were damning themselves and their descendants to the pernicious effects of degeneracy. Raynal proclaimed that "America has not yet produced a good poet, an able mathematician, one man of genius in a single art or a single science.” At one point he even sponsored an essay contest in France on whether the discovery of America had been beneficial or harmful to the human race.
Someone in the fledgling United States was going to have to do something about all this. Enter Jefferson, the natural historian. “Nature,” Jefferson wrote to Pierre-Samuel Dupont, “intended me for the tranquil pursuits of science, rendering them my supreme delight.” Had it not been for “the boisterous ocean of political passions,” Jefferson would likely have spent his time promoting science and losing himself in natural history, chemistry, archaeology, anthropology, agriculture, the velocity of water current, linguistics, meteorology, botany, the measure of latitude and longitude, astronomy, and physics, to name just some of his scientific passions.
The whole degeneracy theory riled Jefferson to the core. He respected Buffon—a man he called a “celebrated Zoologist, who has added and is still adding, so many precious things to the treasures of science”—but on the question of degeneracy, he thought the count had crossed a boundary that should not be crossed. How dare he use natural history in such a fashion¾to damn an entire continent! Jefferson also understood the serious economic implications of Buffon’s theory: Why would Europeans trade with America, or immigrate to the New World, if Buffon and his cadre of degeneracy promulgators were correct? And so, starting in the late 1770s, Jefferson led a sustained scientific assault against Buffon’s theory of degeneracy. It was a two-pronged attack. The first volley appeared in a book.
The longest chapter of Jefferson’s one and only book, Notes on the State of Virginia, was devoted to debunking Buffon’s theory of degeneracy. There was no reason that differences between the New World and the Old should translate into degeneracy in the former, he wrote, “as if both sides were not warmed by the same genial sun; as if a soil of the same chemical composition, was less capable of elaboration into animal nutriment. … The truth is, that a Pigmy and a Patagonian, a Mouse and a Mammoth, derive their dimensions from the same nutritive juices.”
After attacking Buffon’s theoretical framework, Jefferson went after his data—were they accurate, and if not, why not? The theory rested largely on data collected by others, and Jefferson argued that the count’s sources had “casually” collected their data, and what they wrote was based on hearsay. Jefferson challenged the veracity of the travelers upon whom Buffon relied: “who were these travellers?” he asked. Were they reliable, and trustworthy like Buffon? “No, they weren’t,” Jefferson concluded; they had already made up their minds that the Old World was superior to the New before they ever observed any animals, and so they could not be trusted. Jefferson took on each of Buffon’s claims about degeneracy, using a series of tables enumerating the weights of animals from Europe and America. The data, Jefferson showed, simply didn’t support this the dangerous theory Buffon was propounding.
Jefferson got some help from one of the other founding fathers. James Madison and Jefferson exchanged letters focused on issues such as whether and how to hold a Constitutional Convention, whether paper money should be adopted, and what to do about an empty treasury. In these personal correspondences, Madison also provided his friend with ammunition to counter the claims coming out of Europe. In one long letter to Jefferson, after addressing various pressing political issues and noting, “I have a little itch to gain a smattering in chymistry,” Madison shared the results of an examination he had made of the weasel.