James Madison Dissects a Weasel


Illustration of two European mustelids, the Belette (Mustela nivalis) and L’Hermine (Mustela erminea), from Volume 7 of Illustrations de Histoire naturelle générale et particulière avec la description du Roy (1758).  James Madison consulted this work when describing his own locally-caught weasel.  Image source: Wikimedia Commons.

Just a few years before authoring the U.S. Constitution’s Bill of Rights, James Madison (1751 – 1836) was sitting at home in his Virginia estate, dissecting a weasel and writing up his detailed results in a letter to Thomas Jefferson (1743 – 1826).

This letter — dated June 19th, 1786 — is a remarkable one, the sort of enlightened discourse one imagines of such great minds.  It begins with a discussion about the nature of poverty in Europe (described by Jefferson in a previous letter) and the United States, as well as the presumptive role the mode of government had in shaping the existence of the poorer classes.  A little report on the weather and the crops, then Madison expresses “. . . a little itch to gain a smattering in chymistry.  Will you be kind eno’ to pick up some good elementary treatise for me. . .[?]”  There is a brief paragraph on pushing through a state legislative bill for road repair and maintenance.  Then come the weasels.


James Madison, statesman of Virginia, co-author of the “Federalist Papers”, architect of the Constitution and Bill of Rights, 4th President of the United States, dissector of weasels.  Image credit: Gilbert Stuart: The Complete Works.

Madison explains that the body of a female weasel (Mustela frenata) came into his possession and then continues to fill up over two pages (in this four page letter) with detailed descriptions of the animal.  Here is a taste:

Its colour corresponded with the description given by D’Aubenton of the Belette & Roselet or Hermine in its summer dress, excepting only that the belly &c. which in the European animal was white, was in ours of a lightish yellow, save only the part under the lower jaws which was white for about ½ an inch back from the under lip. The little brown spots near the corners of the mouth mentioned by D’Aubenton were peninsular. The tail was of the color of the back &c. all but the end which was black. The ears were extremely thin, had a fold or duplication on the lower part of the conque about 2 lines deep, and at the margin all around were covered with a very fine short hair or fur of the colour nearly of the back. The rest of the ear was in a manner naked, and of a lightish color.

Madison just keeps on going. . . .  and these were not just superficial observations.  The man measured weasel kidneys in three dimensions and counted the number of ridges in the palate.  Whether to wife Dolley’s consternation or approval we may never know, but Madison was digging into the anatomy of small mammals with the same sort of intensity with which he approached national constitutions.


An example of the beast in question:  the Long-Tailed Weasel (Mustela frenata).  Weasels are fierce little carnivores, occasionally taking down prey many times their own size.  Image credit: Evan Jenkins via Flickr.

There is little doubt that Madison was emulating his correspondent and role model Jefferson by drawing up charts comparing a variety of anatomical measurements between his weasel and the European “Belette” and “Hermine.”  These tables of measurements reflect those published by Jefferson the previous year in his Notes on the State of Virginia (1785).  What Madison was doing was comparing the anatomy of his American weasel with European species as described by the natural history authority, Louis Jean Marie Daubenton (1716 – 1800), for the purpose of building up evidence against Old World ideas about biology.  Madison’s specific conclusion from his dissection of the weasel:

The result of the comparison seems to be that notwithstanding the blackness of the end of the tail & whiteness of the feet, which are regarded as characteristics of the Hermine contradistinguishing it from the belette, our weasel cannot be of the former species, and is nothing more than a variety of the latter. This conclusion is the stronger, as the manners of our weasel correspond more nearly with those of the Belette, than with those of the Hermine. And if it be a just conclusion, it may possibly make one exception to Buffon’s position that no animal is common to the two continents that cannot bear the climate where they join; as it certainly contradicts his assertion that of the animals common to the two continents, those of the new are in every instance smaller than those of the old.

In this last statement, Madison is referring to prominent French naturalists such as Daubenton and the Comte de Buffon (1707 – 1788) who claimed that America was only capable of producing puny counterparts to European species.  This notion of degeneracy was summarized by Jefferson in Notes on the State of Virginia:

The opinion advanced by the Count de Buffon is 1. That the animals common to both 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: and 4. That on the whole it exhibits fewer species.  And the reason he thinks is, that the heats of America are less. . . . that heat is friendly, and moisture adverse to the production and development of large quadrupeds.

It did not take much imagination to figure out that degeneracy applied not just to animals, but to people as well.  This was a humiliating and detrimental statement against a newly-birthed nation striving to assert its independent identity and ability to thrive in the face of global skepticism.  It was also blatantly contradictory to what Americans observed daily on their farms, in the forests, and in the ranks of their own fellow citizens.  Men like Madison and Jefferson — as well as Benjamin Franklin, John Adams, and Alexander Hamilton — were infuriated by such pretentious Old World assumptions about the New World (Dugatkin 2009), assumptions that were not based on records of observed facts, but upon some kind of arbitrary, feel-good narrative.  No sophisticated argument was necessary to simply show that North American animals are not categorically diminutive compared to European ones.  But it was still important to make sure those data were carefully collected and circulated.  Eventually, the idea of degeneracy lost steam and died out.


Madison’s letter to Jefferson included this rather spectacular table of measurements comparing his weasel (left column) with European species (middle and right columns).  As Mythbuster Adam Savage said:  “Remember kids, the only difference between screwing around and science is writing it down.”  Well, honestly, I cannot imagine Madison screwing around.  Image credit: Library of Congress.

I wonder if it should be remarkable to us in this modern age, to learn that these men who led the American Revolution and the early days of the Republic — many of whom would serve as President of the United States — engaged in what we would recognize as science.  They were not necessarily scientists, though they thought scientifically.  Science also had a broader meaning in the 18th century, a meaning that stood at the foundation of the Enlightenment ideal.  Science was the application of empirical, experimental studies for the betterment of the human condition.  Science was the triumph of reason and Nature’s laws over fanaticism.

Take, for example, wealthy farmers such as Jefferson, Madison, George Washington, and John Adams.  They were all involved in agricultural research of some sort, keeping extensive multi-year records in an effort to develop better compost mixes, meteorological predictions, plant cultivars best suited for a given climate, and methods of crop rotation (Engle 2002; Druckenbrod et al. 2003; “George Washington and Agriculture”).  Of course, increasing crop yields did contribute directly to personal gains in wealth, but it was also about making gains in national wealth.  As gentlemen farmers, these men felt an obligation to be the experimenters because they were in a better position to absorb the costs of failure impossible for smaller subsistence farmers (“George Washington and Agriculture”).  What they learned, they shared in the interest of making the new United States a profitable and self-sustaining continent.  In turn, this made the largely isolationist policy of the Early Republic possible during those vulnerable, fledgling years.

Science had a real impact on the fate of the United States.  Jefferson, Madison, Washington, Adams, and their compatriots understood this.

Science continues to have a real impact on the fate of the United States and the world, but I am much less confident that our elected leadership understands this.

For all the things we may find distasteful, hypocritical, or abhorrent about the 18th century world that produced the Age of Enlightenment, I think we still must admire the dedication to the painstaking business of improving the state of humankind through reason, sympathy, and a better understanding of Nature.  Certainly, science has changed a lot since the days of Madison dissecting a weasel at home in Montpelier.  A lot of research now requires specialized facilities and training only available through higher level university education.  There are increasingly more specialized niche fields with their own language and communities, each one producing more published literature than can possibly be consumed or understood.  But this is no excuse to reject science.  This is no excuse to ignore the thousands upon thousands of scientists reaching out to the public and shouting themselves hoarse over the reality of climate change.

We must strive to be James Madisons and Thomas Jeffersons in our own right.  Let us be driven by intellectual curiosity for the world around us.  Let us be willing to get our hands dirty to study the evidence for ourselves.  Let us share what we have found through thoughtful civil discourse.  And let us not easily dismiss the weasel as insignificant — for even the small and eccentric can hold the key to some big ideas!


Druckenbrod, Daniel L. et al.  2003.  “Late-Eighteenth-Century Precipitation Reconstructions from James Madison’s Montpelier Plantation.”  American Meteorological Society:  57 – 71.

Dugatkin, Lee Alan.  2009.  Mr. Jefferson and the Giant Moose:  Natural History in Early America.  Chicago, IL:  University of Chicago Press.

Engle, Corliss Knapp.  2002.  “John Adams, Farmer and Gardener.”  Arnoldia 61 (4):  9 – 14

George Washington and Agriculture.”  The Digital Encyclopedia of George Washington.  Accessed 14 November 2016.

Jefferson, Thomas.  1786.  Notes on the State of Virginia.  Published in The Portable Thomas Jefferson.  1975.  Merrill D. Peterson, ed.  New York, NY:  Penguin Books.

Jefferson, Thomas, and James Madison. James Madison to Thomas Jefferson, June 19, 1786.  1786. Manuscript/Mixed Material. Retrieved from the Library of Congress.  Accessed 11 November 2016.



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