A third of a century later, the historian Joseph J. Ellis took the same position. He derided the story as a “piece of scandalous gossip” that had affixed itself to Jefferson’s reputation “like a tin can that then rattled through the pages of history.” Jefferson historians had no desire to know what might be in the tin can; they just wanted to boot it as far away as possible. “Within the community of Jefferson specialists, there seems to be a clear consensus that the story is almost certainly not true,” Ellis wrote in 1996. “After five years mulling over the huge cache of evidence that does exist on the thought and character of the historical Jefferson, I have concluded that the likelihood of a liaison with Sally Hemings is remote.”329
The community of Jefferson specialists found much more to their taste a self-serving story concocted by the Jefferson family to protect his reputation. Two of Jefferson’s grandchildren put it about that Jefferson’s nephews Peter and Samuel Carr were the fathers of the light-skinned slaves at Monticello. The Carrs were the sons of Jefferson’s sister, which could explain why the young slaves so resembled Jefferson.
There the matter rested, so far as scholars were concerned, and might well have solidified into accepted fact, but for the trespass of two outsiders onto the historians’ carefully groomed turf. An African American lawyer, Annette Gordon-Reed, weighed the same evidence available to the historians but came to the opposite conclusion. A Jefferson-Hemings liaison was very likely, she argued, though it could not be proved. That finding led her to a harsher, but not so unreasonable, judgment that “those who are considered Jefferson scholars have never made a serious and objective attempt to get the truth of this matter.”330 Gordon-Reed had no genetic evidence available to her; she simply interpreted the available historical evidence more skillfully than a generation of professional historians had done.
The second outsider to the issue was Eugene Foster, a pathologist who had recently retired from Tufts University to Charlottesville, Virginia. Foster had no particular interest in Jefferson, but Charlottesville is Jefferson country, and a friend asked him one day if DNA fingerprinting might shed any light on the Hemings issue. Foster decided it wouldn’t—forensic DNA analysis can identify individuals and resolve paternity but can’t reach back up a genealogical tree because of the shuffling of DNA between generations. Then he learned of work on the Y chromosome, which is passed unchanged from father to son except at its very tips, and realized it could hold the answer.
First Foster needed a sample of Jefferson’s Y chromosome. Unfortunately Jefferson had no male descendants, but his paternal uncle Field Jefferson would have carried the same Y chromosome, assuming no illegitimacy in the Jefferson male line. With the help of Herbert Barger, a Jefferson family historian, Foster located 5 male descendants of Field Jefferson and wrote explaining his project and asking for a sample of their blood.
Next, he needed a Y chromosome of the Carr brothers, the leading suspects in the view of historians and the Jefferson family members. He obtained blood from three male-line descendants of the three sons of John Carr, the grandfather of Peter and Samuel.
FIGURE 11.1. THOMAS JEFFERSON’S FAMILY WITH SALLY HEMINGS.
A Y chromosome analysis of Thomas Jefferson’s family performed by Eugene Foster and Chris Tyler-Smith showed that Eston Hemings, a son of the slave Sally Hemings, carried the same Y chromosome as that of Thomas Jefferson’s male relatives and was therefore highly likely to have been Jefferson’s son.
At specific sites on the chromosomes, short DNA sequences are repeated a number of times, as in ATATAT. The number of repeats changes quite often between generations, so can be used to identify different lineages. In this case the repeats at 11 sites have been used to fingerprint the different Y’s. A natural shift in repeat numbers at the 9th site has occurred in the rightmost of Field Jefferson’s descendants
Eston Hemings had the same 11 repeats as the Field Jefferson descendants, so would have acquired his Y chromosome from a Jefferson family member, who from the historical evidence was almost certainly Thomas Jefferson, the third president of the United States. The finding strongly supports contemporary rumors that Jefferson had fathered a secret family with Sally Hemings, his slave mistress.
Of Sally Hemings’s descendants, Foster collected blood from a male-line descendant of Eston, her youngest son, who was born in 1808 and is said to have borne a striking resemblance to Thomas Jefferson.
In addition he took samples from 5 male line descendants of Thomas Woodson. There is a strong oral tradition among long-separated branches of the Woodson family that Thomas was a son of Thomas Jefferson who was sent away from Monticello as a boy. There is one other reference, besides James Callender’s, to a slave son of Jefferson named Tom. But there is no documentary evidence showing Thomas Woodson’s presence at Monticello, nor is he named by Madison Hemings in his list of Sally’s children.
Foster had his blood samples analyzed in the laboratory of Chris Tyler-Smith, the Y chromosome expert at Oxford University, with the following results:• All 5 male-line descendants of Field Jefferson turned out to carry the same distinctive set of markings on their Y chromosome, making it highly probable that the same Y chromosome was carried by the third president.
• All 5 male descendants of Thomas Woodson carried non-Jeffersonian Y chromosomes, ruling out the idea that Jefferson was Thomas Woodson’s father.
• All three male-line Carr descendants carried the same Y chromosome, proving this was the true Carr family Y chromosome.
• The Y chromosome of Eston Hemings’s male-line descendant was a perfect match to the Jefferson family Y chromosome, and differed from that of the Carrs.
The “simplest and most probable explanations for our molecular findings,” Foster and his colleagues wrote, “are that Thomas Jefferson, rather than one of the Carr brothers, was the father of Eston Hemings Jefferson, and that Thomas Woodson was not Thomas Jefferson’s son.” They could not rule out the possibility that some male Jefferson other than Thomas had fathered Eston, they wrote. “But in the absence of historical evidence to support such possibilities, we consider them to be unlikely.”331
The DNA evidence by itself does not prove conclusively that Thomas Jefferson had an unacknowledged family with Sally Hemings. Nor does the historical evidence by itself. But for two entirely independent kinds of evidence to point so strongly to the same conclusion makes a robust case. The historian Joseph Ellis certainly felt so, and to his credit admitted error. “The new evidence persuaded me that I had been wrong, and I felt a kind of moral and professional obligation to say that,” he said.332
Barger, the historian who helped Foster, was not pleased by this outcome. He has assailed Foster’s findings and proposed other male Jeffersons as the father of Eston, just as the Jefferson grandchildren did on an earlier occasion. But none of these ad hoc candidates can be shown to have been present at Monticello at all of Sally Hemings’s conceptions as Thomas Jefferson was.
Jefferson had a strange and special tie with Sally Hemings, one only possible in the divided world of slave and free. No portraits of Sally survive, but she may well have reminded Jefferson of his beloved wife Martha, being as she was Martha’s half sister. Both were daughters of John Wayles, Martha by his wife Martha Eppes, Sally by the slave Elizabeth Hemings, who became Wayles’s mistress after his wife’s death.
Jefferson’s feelings for Sally, a subject of much speculation, are simply unknown. In all his correspondence he mentions her just once. At Monticello his white family and his unacknowledged black family lived side by side, but even in private he seems to have paid no special attention to Sally’s children. Madison learned to read, he says, “by inducing the white children to teach me the letters and something more.” As for Jefferson, “He was not in the habit of showing partiality or fatherly affection to us children. We were the only children of his by a slave woman.”
Some mysteries lie beyond the power even of DNA to resolve.
12
EVOLUTION
The main conclusion arrived at in this work, namely, that man is de
scended from some lowly organised form, will, I regret to think, be
highly distasteful to many. But there can hardly be a doubt that we are
descended from barbarians. The astonishment which I felt on first
seeing a party of Fuegians on a wild and broken shore will never be
forgotten by me, for the reflection at once rushed into my mind—such
were our ancestors. These men were absolutely naked and bedaubed
with paint, their long hair was tangled, their mouths frothed with
excitement, and their expression was wild, startled, and distrustful.
They possessed hardly any arts, and like wild animals lived on what
they could catch; they had no government, and were merciless to every
one not of their own small tribe. . . . Man may be excused for feeling
some pride at having risen, though not through his own exertions, to
the very summit of the organic scale; and the fact of his having thus
risen, instead of having been aboriginally placed there, may give him
hope for a still higher destiny in the distant future. But we are not here
concerned with hopes or fears, only with the truth as far as our reason
permits us to discover it; and I have given the evidence to the best of my
ability. We must, however, acknowledge, as it seems to me, that man
with all his noble qualities, with sympathy which feels for the most
debased, with benevolence which extends not only to other men but to
the humblest living creature, with his god-like intellect which has pen
etrated into the movements and constitution of the solar system—with
all these exalted powers—Man still bears in his bodily frame the in
delible stamp of his lowly origin.
CHARLES DARWIN, THE DESCENT OF MAN
LOOK BACK at the 5 million years since the human line split from that of apes. With the power of genetics, that story can now be told at a far deeper level of detail, abundantly confirming the extraordinary insight that Darwin first hinted at in his On the Origin of Species of 1859 and made more explicit in The Descent of Man in 1871. Humans are just one of the myriad branches of the tree of life, sharing the same fundamental genetic mechanisms as all other living species, and shaped by the same evolutionary forces. This is the truth, as far as our reason permits us to discover it. All differing accounts of human origin, though a matter of religious dogma for most of recorded history and widely believed to the present day, are myth.
Darwin’s insight was the more remarkable because he had no concept of genes, let alone of DNA, the chemical script in which the genetic instructions are inscribed. Not until 1953 was DNA recognized to be the hereditary material and only since 2003 has the fully decoded script of the human genome been available for interpretation.
With this script in hand, we can begin to trace the finest workings of the grand process that Darwin could see only in outline. The picture is still far from complete. But as the previous chapters have recorded, a wealth of information has already been retrieved from the darkness. We can see how the human form was shaped, step by step, from the anatomy of an apelike fore-bear, losing its body hair and developing darker skin as recorded in the gene for skin color. Human behavior, whether in the search for reproductive advantage or the defense of territory, shows clear continuity with that of apes. But it also developed its own characteristic pattern with two pivotal steps: the emergence of long lasting bonds between men and women some 1.7 million years ago, and at 50,000 years ago the evolution of language. Language, a novel evolutionary faculty enabling individuals to share a sequence of precise thoughts symbolically, opened the door to a new level of social interaction. Early human groups developed the institutions that shape even the largest and most sophisticated of today’s urban societies. These included organized warfare; reciprocity and altruism; exchange and trade; and religion. All were present in embryo in the hunter-gatherer societies of the Upper Paleolithic. But it required another development, a diminution of human aggression and probably the evolution of new cognitive faculties, for the first settlements to emerge, beginning 15,000 years ago, and it was in the context of settled societies that warfare, trade and religion attained new degrees of complexity and refinement.
Human nature is the set of adaptive behaviors that have evolved in the human genome for living in today’s societies. We have developed, and can execute instinctively, the behaviors necessary for warfare, for trade and exchange, for helping others as if they were kin, for detecting outsiders and cheaters, and for immersing our independence in the religion of our community.
The narrative of the human genome explains our origins, our history, and our nature, but many of its implications are far from welcome to one group or another. “The human mind evolved to believe in the gods. It did not evolve to believe in biology,” writes Edward O. Wilson.333 Religion is not the only subject for which evolution provides a discordant view of the world. Geneticists are likely to provide ever greater detail about how individuals vary, how men and women have different interests and abilities, and how races differ. Scientists studying the genome may in time establish that many human motives, from mating behavior to traits of personality, are shaped by genetically based neural circuits, thus casting some doubt on the autonomy of human actions. But however discomforting such findings may be, to falter in scientific inquiry would be a retreat into darkness.
One of the most perplexing implications of Darwin’s theory is that humans are the unplanned product of a blind and random process. Looking at our cousins, the chimpanzees, we seem so much more advanced than they, as if shaped for a higher purpose. This is in part an illusion our ancestors helped to create by eliminating all competing human species. The more deeply we understand chimpanzees, the more evident their similarities to people become. They are shaped from the identical clay, the gene pool of our common ancestor. Some 99% of their DNA sequence corresponds almost exactly to our own.334 They are highly intelligent, feel empathy for others, fabricate a variety of tools, and lead a complex social life. But by chance and circumstance, chimpanzees took one path through evolutionary space, the human lineage took another. Perhaps the chimp path required rather little change, whereas the human lineage, seeking a way of life beyond the trees, became so different because it was constantly forced to innovate.
The relentless search for new solutions produced not one but a whole clutch of hominid species. At least three—the Neanderthals, Homo erectus, and Homo floresiensis—survived until modern humans made their exit from Africa. Had these archaic peoples endured till the present day, our own species would surely seem less special, being evidently just one of many ways in which evolution could spin variations out of the basic ape lineage.
But if evolution generates new species by mechanisms that are in part random, should human existence be ascribed just to a long sequence of chance events? In the passage quoted above, that concludes his Descent of Man, Darwin gives a typically careful answer, a yes with a reservation. Man has risen to the summit of the organic scale, he says, “though not through his own exertions.” Yet “some pride” in the result would be excusable. Why so, if no human exertion was involved? The reference a few lines later to man’s powers of sympathy, benevolence and intellect is presumably Darwin’s answer, and we can perhaps begin at last to see what he meant.
Though evolution through natural selection depends on random processes, it is shaped by the environment in which each species struggles to survive. And for social species the most important feature of the environment is their own society. So to the extent that people have shaped their own society, they have determined the conditions of their own evolution.
The nature of this interaction between culture and evolution is not yet clear, because it has only just come to light. It has long been ass
umed by historians, archaeologists and social scientists that human evolution was completed in the distant past, probably before any kind of culture had begun, and that there has been no evolutionary change, or only a negligible amount, within the last 50,000 years or so. Even evolutionary psychologists, who are committed to explaining the mind in terms of what evolution shaped it to do, assume that evolution’s work was completed in a preagricultural past more than 10,000 years ago.335
But the evidence now accumulating from the genome establishes that human evolution has continued throughout the last 50,000 years. The recent past, especially since the first settlements 15,000 years ago, is a time when human society has undergone extraordinary developments in complexity, creating many new environments and evolutionary pressures. Hitherto it has been assumed the human genome was fixed and could not respond to those pressures. It now appears the opposite is the case. The human genome has been in full flux all the time. Therefore it could and doubtless did adapt to changes in human society. And this may mean that people have adapted in various ways, both good and bad, to the kinds of society they lived in.
Following is a review of the evidence that evolution is an active and vigorous force in the human population, a brief look at some of the implications, and a discussion of where human evolution might be headed in the future.
Before the Dawn: Recovering the Lost History of Our Ancestors Page 32