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.

Madison went into great detail, noting that “the membrane of the Bladder very thin,” “the spleen was of the same color on both sides,” and “its smell was a sort of rankish musk, but not so strong as to be very offensive.” Madison also enclosed a table with measurements on everything from the “width of the ears horizontally” to a more delicate measure of the “distance between the anus and the vulva.” Madison’s enumeration of all things American weasel was contrasted with similar measurements Buffon had made of related European species. Madison concluded that the data “certainly contradicts [Buffon’s] assertion that of the animals common to the two continents, those of the new are in every instance smaller than those of the old.”

Notes on the State of Virginia, along with the research Jefferson inspired in Madison and others, was the intellectual component of Jefferson’s two-pronged assault on Buffon’s theory. But he also understood the power of the physical—that sometimes you have to hand someone evidence that is so overwhelming that even the staunchest advocate changes his position. For Jefferson, that would be a giant moose, preferrabley one 7 to 10 feet tall.

With classic Jeffersonian obsessiveness, he undertook a quest to find such a creature. He began circulating a 16-question survey on the habits, size, and natural history of the moose to his friends. Gen. John Sullivan—a representative at the second Continental Congress, a prisoner during the battle for independence, and attorney general of New Hampshire—quickly emerged as his point man in this effort. Sullivan exchanged many moose-centric letters with Jefferson. At times the general hinted that a moose sufficient for the cause would soon be procured by his friends or a hunter his friends paid, but as Jefferson sailed to Paris in the summer of 1784, no giant moose had been bagged.

In late 1785, Jefferson dined with Buffon in the count’s summer mansion outside Paris. Jefferson found that Buffon was “absolutely unacquainted” with the American moose and thought it was simply a miscategorized reindeer. Jefferson told the count “that the rein deer could walk under the belly of our moose.” Jefferson noted that Buffon had “entirely scouted the idea.” Finally, though, Buffon relented and hinted that if Jefferson could present him with the antlers of a giant moose, he would pull back—either by omission or by an admission of error, it isn’t clear from the historical record which—his theory of degeneracy in the next volume of Histoire Naturelle.

Jefferson wrote to Sullivan begging for a moose: “The readiness with which you undertook to endeavor to get for me the skin, the skeleton and the horns of the moose … emboldens me to renew my application to you for those objects, which would be an acquisition here, more precious than you can imagine. … Address them to me, to the care of the American Consul of the port in France to which they come.”

Soon thereafter Sullivan wrote Jefferson that, at long last, he had obtained the long-sought moose, and that the carcass was en route “on the Connecticut River,” and was expected “as soon as the roads are broken through the snow which is now very deep.” It took 14 days before the moose arrived at Sullivan’s home on April 3, 1787.

The weeks of transport took a heavy toll on the moose’s carcass; Sullivan and his team had particular trouble preserving the skull bones and antlers. They reconstructed the moose as best they could, but they couldn’t salvage the antlers. Sullivan sent another pair instead, telling his friend, “they are not the horns of this moose but may be fixed on at pleasure.”

After many twists and turns, including almost being lost at a ship dock, the remains of a 7-foot-tall moose arrived at Le Havre De Grace sometime around Oct. 1, 1787. An ecstatic Jefferson wrote to Buffon that he was “happy to be able to present you at this moment the bones and skins of a moose, [and] the horns of [another] individual.” For good measure, Jefferson suggested that the moose be “stuffed and placed on his legs in the king’s cabinet.”

Buffon received the moose, and Jefferson wrote in his journal that the skin and skeleton “convinced Mr. Buffon. He promised in his next volume to set these things right.” But Jefferson’s timing was poor. Within six months of receiving Jefferson’s moose, Count Buffon was dead, and there would be no retraction of the theory of New World Degeneracy in Histoire Naturelle.

Jefferson feared the degeneracy argument would have a life of its own, long outlasting its creator. He was right—degeneracy fit into a Eurocentric view of the world too well to be set aside by people who thought themselves naturally superior to all others. For the next 70 years, European thinkers would line up to defend the theory of degeneracy.

Fortunately, there were Americans to counter them. One of my favorite examples is the Rev. Jedidiah Morse, grandfather to Samuel of code fame, and an influential New England Congregationalist pastor during the Second Great Awakening. Morse wrote a popular 1790 textbook, The History of America in Two Books. When young Americans stepped into their school house and cracked open their history book, they immediately learned of Buffon’s degeneracy theory and were told in no uncertain terms how utterly misguided such slander from Europe really was.

Students read of the “extreme malignity of climate [that] has been inferred and asserted” by people like Buffon and his groupies, and a large part of Chapter 1 of The History of America quotes these ideas at length, so students could see for themselves the sort of material that European philosophers were writing about their country. Morse cataloged many instances in which the degeneracy camp simply had its numbers wrong. Insects and vermin weren’t more common in America¾the Old World had just as many swarms of “disgustful insects” as the New. American students learned that Louisiana was not, in fact, teeming with frogs weighing 37 pounds. Morse explained to the young minds reading his book that degeneracy was the product of the “ignorance or … studied forgetfulness of … the Old continent.” Educators across the new nation were determined to show young schoolchildren how misguided the theory of New World Degeneracy was. Some 50 years later, James Fenimore Cooper would make reference to the preamble of a charter to found a new Colonial school, which read: “Whereas the youth of this colony are found, by manifold experience, to be not inferior in their natural geniuses to the youth of any other country in the world.”

Some lessons were important enough to be taught over and over.

