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Jefferson’s Old Bones

Did the so-called father of American vertebrate paleontology believe in fossils?

Keith Thomson

Father or Not?

For his analysis of the mastodon and description of Megalonyx, historians have often called Jefferson the father of American vertebrate paleontology. Sixty-five years ago, however, paleontologist George Gaylord Simpson, in a masterly review of the history of American vertebrate paleontology, argued that Jefferson did not deserve this accolade because his actions were not sufficiently scientific. Simpson points out that Jefferson did not believe in extinction partly on religious grounds, and in his paper on Megalonyx, he started with a theory (that the animal was some kind of gigantic American lion) and then tried to prove it, rather than first assembling the facts. Both of these charges are true. But the situation turns out to be rather more complicated than Simpson thought.

2011-05MargThomsonFB.jpgClick to Enlarge ImageThe first defense against Simpson’s charge is that Jefferson’s views on extinction were not simply, and certainly not only, a matter of religious prejudice—although it is true that Jefferson was a deist who thought that the Creator had made the world just once, and as it is now. He wrote to John Adams in 1823 of his beliefs:

The movements of the heavenly bodies, so exactly held in their course by the balance of centrifugal and centripetal forces, the structure of our earth itself, with its distribution of lands, waters and atmosphere, animal and vegetable bodies, examined in all their minutest particles, insects mere atoms of life, yet as perfectly organized as man or mammoth, the mineral substances, their generation and uses, it is impossible, I say, for the human mind not to believe that there is, in all this, design, cause and effect, up to an ultimate cause, a fabricator of all things from matter and motion, their preserver and regulator …

In fact, Jefferson did recognize the obvious fact that species and populations—such as the wolf and bear in Britain, or various American Indian groups—became extinct. He also believed that nature compensated for such losses. The sentence quoted above continues, “while permitted to exist in their present forms, and their regenerator into new and other forms.” Furthermore, in the same letter he wrote:

We see … evident proofs of the necessity of a superintending power to maintain the Universe in its course and order … Certain races of animals are become extinct; and, were there no restoring power, all existence might extinguish successively, one by one, until all should be reduced to a shapeless chaos.

As for the mastodon and Megalonyx, Jefferson, the lawyer, simply argued “the bones exist; therefore the animal has existed.… If this animal then has once existed, it is probable … that he still exists.” But he also argued like a scientist. In his paper on Megalonyx he devoted a full four (out of 14) pages to reports from western travelers of encounters like those cited above. In this sense, his view of extinction can be seen as a hypothesis for which he cited evidence in support.

A more difficult question concerns Jefferson’s understanding of what his mastodon and Megalonyx bones actually were. It is impossible to open any work about Jefferson and his collections without finding a reference to Jefferson’s love of “fossils.” But a careful search of Jefferson’s writings (now made possible by the availability of searchable databases) reveals the surprising fact that he never referred to them as fossils. For him they were always simply “bones.” The word “fossil” does not appear in Notes on the State of Virginia or his letters.

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