---
title: "Thomas Jefferson"
chunk: 17/19
source: "https://en.wikipedia.org/wiki/Thomas_Jefferson"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T04:06:33.894887+00:00"
instance: "kb-cron"
---

Claims that Jefferson fathered children with his slave Sally Hemings after his wife's death have been debated since 1802. In that year James T. Callender, after being denied a position as postmaster, alleged Jefferson had taken Hemings as a concubine and fathered several children with her. In 1998, a panel of researchers conducted a Y-DNA study of living descendants of Jefferson's uncle, Field, and of a descendant of Hemings's son, Eston Hemings. The results showed a match with the male Jefferson line. Subsequently, the Thomas Jefferson Foundation (TJF) formed a nine-member research team of historians to assess the matter. The TJF report concluded that "the DNA study ... indicates a high probability that Thomas Jefferson fathered Eston Hemings". The TJF also concluded that Jefferson likely fathered all of Hemings's children listed at Monticello.
In July 2017, the TJF announced that archeological excavations at Monticello had revealed what they believe to have been Sally Hemings's quarters, adjacent to Jefferson's bedroom. Since the results of the DNA tests were made public, the consensus among most historians has been that Jefferson had a sexual relationship with Sally Hemings and that he was the father of her son Eston Hemings.
A minority of scholars maintain the evidence is insufficient to prove Jefferson's paternity conclusively. Based on DNA and other evidence, they note the possibility that additional Jefferson males, including his brother Randolph Jefferson and any one of Randolph's four sons, or his cousin, could have fathered Sally Hemings's children. In 2002, historian Merrill Peterson said: "in the absence of direct documentary evidence either proving or refuting the allegation, nothing conclusive can be said about Jefferson's relations with Sally Hemings." Concerning the 1998 DNA study, Peterson said that "the results of the DNA testing of Jefferson and Hemings descendants provided support for the idea that Jefferson was the father of at least one of Sally Hemings's children".
After Jefferson's death in 1826, although not formally manumitted, Sally Hemings was allowed by Jefferson's daughter Martha to live in Charlottesville as a free woman with her two sons until her death in 1835. The Monticello Association refused to allow Sally Hemings' descendants the right of burial at Monticello.

== Interests and activities ==

Jefferson was a farmer, obsessed with new crops, soil conditions, garden designs, and scientific agricultural techniques. His main cash crop was tobacco, but its price was usually low and it was rarely profitable. He tried to achieve self-sufficiency with wheat, vegetables, flax, corn, hogs, sheep, poultry, and cattle, but he lived perpetually beyond his means and was always in debt. Jefferson also planted two vineyards at Monticello and hoped to grow Vitis vinifera, the European wine grape species, to make wine, but the crop failed. His efforts were nonetheless an important contribution to the development of American viticulture.
Jefferson mastered architecture through self-study. His primary authority was Andrea Palladio's 1570 The Four Books of Architecture. Jefferson helped popularize the Neo-Palladian style in the United States, utilizing designs for the Virginia State Capitol, the University of Virginia, Monticello, and others. 
In archaeology in 1784, Jefferson, using the trench method, started excavating a Monacan burial mound in Virginia. His excavations were prompted by him noticing local Native Americans visiting the site and the "Moundbuilders" question. His methods allowed him to witness the stratigraphic layout, the various human remains and other artifacts inside the mound. The evidence present at the site led him to admit that he saw no reason why the ancestors of the present-day Native Americans could not have raised those mounds.
He was interested in birds and wine, and was a noted gourmet. As a naturalist, he was fascinated by the Natural Bridge geological formation, and in 1774 successfully acquired the Bridge by a grant from George III. As an advocate of Enlightenment ideals, Jefferson studied many aspects of the natural sciences and frequently corresponded, and even hosted on multiple occasions, with Prussian explorer, Alexander von Humboldt.

=== American Philosophical Society ===
Jefferson was a member of the American Philosophical Society for 35 years, beginning in 1780. Through the society he advanced the sciences and Enlightenment ideals, emphasizing that knowledge of science reinforced and extended freedom. His Notes on the State of Virginia was written in part as a contribution to the society. He became the society's third president on March 3, 1797, a few months after he was elected Vice President of the United States. 
On March 10, 1797, Jefferson gave a lecture, later published as a paper in 1799, which reported on the skeletal remains of an extinct large sloth, which he named Megalonyx, unearthed by saltpeter workers from a cave in what is now Monroe County, West Virginia. Jefferson is considered to be a pioneer of scientific paleontology research in North America.
Jefferson served as APS president for the next eighteen years, including through both terms of his presidency. He introduced Meriwether Lewis to the society, where various scientists tutored him in preparation for the Lewis and Clark Expedition. He resigned on January 20, 1815, but remained active through correspondence.