One of the advantages of a stronger Union under the Constitution, according to Alexander Hamilton, was that it would allow America to take Europe down a peg. Europe, he wrote impatiently, had grown accustomed "to plume herself as Mistress of the World, and to consider the rest of mankind as created for her benefit." He continued:
Men admired as profound philosophers have, in direct terms, attributed to her [Europe's] inhabitants a physical superiority; and have gravely asserted that all animals, and with them the human species, degenerate in America—that even dogs cease to bark after having breathed a while in our atmosphere. Facts have too long supported these arrogant pretensions of the European. It belongs to us to vindicate the honor of the human race, and to teach that assuming brother moderation.... Let Americans disdain to be the instruments of European greatness!
Earlier in 1787, Thomas Jefferson had finally published his Notes on the State of Virginia, which he had written in 1781-2. In one long section of the work (Query VI), he addresses the contention of the French naturalist Buffon that American mammals were smaller than their European counterparts. Jefferson writes: "The opinion advanced by the Count de Buffon, is 1. That the animals common both to the old and new world, are smaller in the latter. 2. That those peculiar to the new, are on a smaller scale. 3. That those which have been domesticated in both, have degenerated in America..." This is what Hamilton was talking about, and this European presumption irritated Jefferson as much as it did Hamilton. America's national honor was at stake. To the French, who insisted that even the human race degenerated on American soil, Jefferson responded patriotically: "In war we have produced a Washington, whose memory will be adored while liberty shall have votaries, whose name will triumph over time, and will in future ages assume its just station among the most celebrated worthies of the world, when that wretched philosophy shall be forgotten which would have arranged him among the degeneracies of nature."
Fossilized bones identified by Thomas Jefferson as belonging to a giant land sloth, which he named megalonyx (Greek for "giant claw").
Jefferson was convinced that North America had produced large mammals, or megafauna, that rivaled anything in Europe. In the early 1780s, when he wrote Notes on the State of Virginia, he had seen the bones of great mammoths. In the mid-1790s, Jefferson was sent a set of bones which he identified as the bones of a giant ground sloth, later given the name Megalonyx jeffersonii in his honor. Clearly, the fossil record indicated that enormous mammals once roamed the North American continent. Except that Jefferson didn't exactly believe in the fossil record. He thought the mammals must still be out there, perhaps only pushed further west as settlement advanced. He didn't believe in extinctions: "Such is the economy of nature, that no instance can be produced of her having permitted any one race of her animals to become extinct; of her having formed any link in her great work so weak as to be broken." When he sent out Lewis and Clark to explore the newly acquired territories of the Louisiana Purchase, he told them to keep their eyes open for his giant sloth.
But North American megafauna, like Jefferson's giant ground sloth, had gone extinct. One theory is that climate change caused the extinctions, but another theory has been gaining traction that attributes the extinctions, beginning about 13,000 years ago, to hunting by the spear-throwing Clovis people. According to the theory, the North American megafauna had evolved in the absence of human predators, and were unprepared for the Clovis people and their spears. The megafauna that can still be found in North America, like bison, are most likely the descendants Eurasian immigrants who entered the continent over some ice age land bridge. Because they had evolved in the presence of human predators, these newcomers were better equipped to survive.
Hamilton believed that the United States would prosper in proportion to its size. The small individual states were more vulnerable to predation by outside powers than a larger Union of all the states would be. But natural history told a different story. The megafauna were hunted to extinction, while the smaller mammals survived.
For more on the extinction of the North American megafauna, see Alan Weisman, The World Without Us (New York, St. Martin's Press, 2007), chapter 5 ("The Lost Menagerie") and Jared Diamond, Guns, Germs, and Steel (New York, W.W. Norton, 1997), 44-50; or, in more depth, Paul S. Martin, Twilight of the Mammoths: Ice Age Extinctions and the Rewilding of America (Berkeley, University of California Press, 2005).