She Has Her Mother's Laugh: The Powers, Perversions, and Potential of Heredity (32 page)

One sunny late-winter day, I drove down Bungtown Road, along the southern edge of the Long Island Sound, and then climbed a high hill to reach the lab. I parked my car and used a map to navigate my way past a bell tower. The tower housed a staircase in the shape of a DNA double helix. The letters of the four bases,
a
,
c
,
g
, and
t
, were engraved high on its four walls.

I shuffled down broad steps to a cluster of research buildings. Inside one of them I found the office of a young scientist named Adam Siepel. He welcomed me in and had me sit at a table below a giant monitor bolted to a wall. Siepel had a high forehead and kept his hair cropped to near-baldness. He kept a miniature rock garden on a shelf by his desk, a rivulet running through the center and making an endless burble. Near his window, Siepel had set a picture of his young son and daughter. Next to the photo was a peculiar skull, with a brow ridge sloped like a trough. It was a cast of a Neanderthal head.

Ancestor and descendants, I thought.

A century beforehand, the scientists who worked at Cold Spring Harbor would not have taken kindly to the pride of place Siepel gave a Neanderthal. To Charles Davenport and his fellow eugenicists, Neanderthals were nothing more than a brutish victim of humanity's progress, a race below all other races.

Davenport would sometimes travel the forty miles from Cold Spring Harbor to New York City. There he would attend the meetings of the Galton
Society at the American Museum of Natural History. Davenport had helped found the society, along with
Henry Fairfield Osborn, the president of the museum. It was made up of scientists and wealthy businessmen dedicated to putting eugenics to work in order to save American society. At their meetings, the Galton Society would grouse about Negroes, immigrants from the wrong parts of Europe, and the feebleminded.

Invitations, Davenport once said, were “
confined to native Americans.” He did not mean Cherokees.

Osborn had made his scientific mark as a paleontologist who studied mammal evolution. But by the early 1900s, eugenics became his overriding mission. “
Heredity and racial predisposition are stronger and more stable than environment and education,” he declared. Osborn could not explain genetics to the public as effectively as Davenport or other members of the Galton Society. But he could supply eugenics with its evolutionary backstory. Osborn promoted a eugenic picture of mankind in bestselling books. He even used his museum for the cause, designing its first exhibit about human evolution.

Examining the fossil record of the early 1900s, Osborn argued that central Asia was a nursery for the evolution of new kinds of mammals. Once they evolved there they expanded outward to other continents in a series of waves. Apes and humans were no different, Osborn believed: Their new forms also emerged from the Asian nursery. Each new wave was more sophisticated than the previous one, often eradicating them when they met.

One of the earliest waves to emerge from Asia, Osborn claimed, was the Neanderthals. In 1856, quarry workers in Germany had found the first fragments of Neanderthal fossils. They suggested heavyset humans with thick brow ridges. By the early 1900s, more Neanderthal fossils had emerged across Europe. Looking at their bones, Osborn pictured a lumbering brute: “
an enormous head placed upon a short and thick trunk, with limbs very short and thick-set, and very robust; the shoulders broad and stooping.” Even the hands of Neanderthals seemed huge and clumsy to Osborn, who said they were “without the delicate play between the thumb and fingers characteristic of modern races.”

On tours of Europe, Osborn would visit caves to acquaint himself with Neanderthal remains. He could see that Neanderthals had been capable of hunting big game like horse and bison. But their stone tools were primitive compared to more recent ones. And no one could find any trace of Neanderthal art. This evidence—or the lack of it—only strengthened Osborn's conviction that Neanderthals had subhuman minds.

Not so agreeable were their giant braincases. If Neanderthals were extinct subhuman brutes, they shouldn't have had brains as big as living humans. Osborn dodged this quandary by ignoring the size of their brains and making much of their shape instead. The Neanderthal brain lacked “
the superior organization of the brain in recent man,” Osborn declared, especially in the prefrontal cortex, “which is the seat of the higher faculties.”

When Osborn established the Hall of the Age of Man in his museum, he had murals and busts of Neanderthals put on display. He ordered them to be depicted as dark-skinned, hairy, and brutish. “
The Neanderthals represent a side branch of the human race which became wholly extinct in western Europe,” he said.

The Neanderthals didn't just quietly disappear, however. They were annihilated by the Cro-Magnons, Osborn believed, a race which had evolved in Asia and which was in no way connected by any ancestral links with the Neanderthals.

Osborn believed that Cro-Magnons were far superior, “a race with a brain capable of ideas, of reasoning, of imagination, and more highly endowed with artistic sense and ability than any uncivilized race which has ever been discovered.” Their superiority, in fact, allowed the Cro-Magnons to wrest control of Europe. “
They were armed with weapons which, with their superior intelligence and physique, would have given them a very great advantage in contests with the Neanderthals,” Osborn said. Judging from this superiority, Osborn believed Cro-Magnons “
probably belonged to the Caucasian stock.”

Along with Caucasians, Osborn recognized Mongoloids and Negroids as “
three absolutely distinct stocks, which in zoology would be given the rank of species, if not of genera.”

Osborn was never very clear about the order in which the three stocks arose, but he was sure that Negroids emerged first. For proof, he pointed to how they fared on Henry Goddard's intelligence tests. “The standard of
intelligence of the average adult Negro is similar to that of the eleven-year-old youth of the species
Homo sapiens
,” he said. Making matters worse, the Negroids had expanded into the tropics, where food was easy to get and intelligence was thus not favored by evolution. “Here we have the environmental conditions which have kept many branches of the Negroid race in
a state of arrested development,” Osborn said.

To Osborn, the history of white people did not end with the Cro-Magnons. The Nordic race of Caucasians arose twelve thousand years ago and swept into Europe. They had the strongest “race plasm,” as Osborn liked to call it, and thus they had produced the greatest men in history, from Columbus to Leonardo da Vinci to Cervantes (never mind that these luminaries were not Nordics, but were born rather in Italy and Spain). To maintain the vigor of the Nordic race, Osborn believed, eugenicists would have to make sure they didn't taint their race plasm by marrying people of the lower races.

In 1935, Osborn died of a heart attack while sitting in his study in his upstate New York mansion. He collapsed as he was “engaged in writing
a 1,250,000-word treatise on the evolution of the elephant,” according to the
New York Times
. Osborn's death occasioned many obituaries and public memorials, which mostly dwelled on his paleontological achievements and his leadership at the museum. They carefully avoided any mention of the fondness he had developed for Nazi Germany, or the visit he paid there a year before his death to accept an honorary degree. By the time Osborn died, eugenics was losing much of its luster.

Osborn's cherished theory of Asian human origins would eventually be proven wrong. By the 1960s, it was becoming abundantly
clear that humans originated in Africa, Osborn's dismal tropical dead end. The oldest humanlike fossil yet found,
Sahelanthropus tchadensis
, lived about seven million years ago in what is now Chad. For the next five million years our ancient relatives, known as hominins, lived as small-brained bipedal apes in
eastern and southern Africa. Starting about two million years ago, waves of hominins began expanding out of Africa to populate Europe and Asia. But the center of hominin evolution remained in Africa.

By 600,000 years ago, the hominins on our own branch of the family tree had evolved to our own height and brain size. They were making sophisticated tools beyond the skill of earlier hominins. They were not just hominins anymore; they could rightly be called humans. Some early humans stayed in Africa and evolved into our species,
Homo sapiens
. Others expanded their range beyond Africa, gradually adapting to life on other continents. That wandering population became the Neanderthals.

Research on Neanderthals since Osborn's death has dramatically improved their reputation. Paleoanthropologists have found the remains of Neanderthals well outside of Europe, as far away as the Near East and Siberia. For more than 300,000 years, they had a range the size of Australia, encompassing mountains, grasslands, and forests. Neanderthals were versatile at finding food. In addition to catching big game, Neanderthals who lived on the coast would fish, kill dolphins, and harvest mussels. Neanderthals knew how to cook the pitch of birch trees into a glue for fixing stone blades to wooden spear handles. They marked their bodies red with ochre and wore jewelry made from the claws of eagles. They arranged stalagmites into enormous circles deep inside caves, perhaps as sites for subterranean worship.

Despite all their newly appreciated adaptations, Neanderthals still disappeared. The youngest Neanderthal sites are forty thousand years old. Our own species may well have played a part in their demise when some Africans expanded into Europe and Asia. Sometimes this expansion took modern humans into Neanderthal territory, where the two kinds of people overlapped for thousands of years.

In 1995, a technician at the Rheinisches Landesmuseum in Bonn, Germany, did something unheard-of: He
switched on a sterile electric saw and pushed it into the fossil of a Neanderthal's arm. This was not just any Neanderthal fossil: It belonged to the first cache of the extinct humans ever discovered, unearthed in 1856 by quarry workers clearing a cave. Now, 139
years later, the technician carved out a C-shaped chunk from the arm fossil. Under the whirring saw blade, it gave off a whiff of burnt bone.

The museum had decided it was time to have a paleogenetics expert look for DNA in some of their fossils, and they chose Svante Pääbo. When they shipped him the Neanderthal bone, Pääbo assigned one of his graduate students, Matthias Krings, to work on it. Krings managed to extract short stretches of mitochondrial DNA from the fossil. One day, he fed the genetic material into a sequencing machine to read it. Krings could only hope that he had not contaminated the sample with the DNA of a living animal, including himself.

The fragment of DNA Krings extracted measured only 379 bases long. He compared it to the same stretch in the mitochondrial DNA of more than two thousand living humans. Most of the fossil DNA matched the human stretches perfectly. But here and there, it had mutations not found in any living person. It differed from every human sequence Krings studied on average by 28 bases.

Late in the night, Krings picked up a laboratory phone to give Pääbo an urgent update.

“It's not human,” he said.

It was the first time anyone had found DNA from an extinct, humanlike fossil. The discovery led Pääbo to undertake a scientific expedition unlike anything that had come before. He and his colleagues persuaded other museums to let them drill other Neanderthal fossils. They enlisted paleoanthropologists to send them fresh material from their digs. Pääbo's group built up a genetic portrait of Neanderthals across their entire range, gathering not just mitochondrial DNA but DNA from their chromosomes as well. Their research revealed that Neanderthals varied from one another, but they had much less variation than living humans do. It became clear that they represented a separate branch of humans that lived in small groups with little genetic diversity.

As new kinds of DNA-sequencing technology became available, Pääbo and his colleagues would snatch them and adapt them to their research. They extracted more DNA from each fossil they studied, and their
reconstructions grew more accurate. In 2010, they managed to build a rough draft of about 60 percent of the entire Neanderthal genome. To understand how it fit into human evolution, Pääbo enlisted David Reich and his colleagues. Base by base, they compared the Neanderthal DNA to that of a chimpanzee and of humans from different parts of the world.

The scientists found that Neanderthals shared many genetic variants in common with modern humans, variants that aren't shared by chimpanzees. These shared variants must have arisen after our hominin ancestors split away from the ancestors of other living apes—but before the split between modern humans and Neanderthals. Pääbo and his colleagues also cataloged a number of variants that arose only in Neanderthals, and others only in the modern human lineage.

But they were still left with some variants that didn't quite fit in any of these categories. These variants were sprinkled in the DNA of some Europeans and Asians they studied. But they couldn't find any in living Africans.

The strongest explanation for the pattern was one that would have appalled Henry Fairfield Osborn. Neanderthals must have interbred with the modern humans who expanded out of Africa and would go on to settle across the Old World (that included the Europeans whom Osborn believed to be his beloved, pure Nordic race). Pääbo and his colleagues estimated that living non-Africans could trace 1 to 4 percent of their genetic ancestry to Neanderthals. There is thus more Neanderthal DNA on Earth today than when Neanderthals existed.

By 2010, when Pääbo and his colleagues published the first evidence for Neanderthal interbreeding, genetic genealogy was a thriving industry. It was ready to seize such a sensational finding and make the most of it. 23andMe quickly put together a test that they claimed could tell customers just how much of their genome was Neanderthal. When I told people about my reporting about Neanderthals, some of them would eagerly let me know about their percentage. The more Neanderthal DNA they carried, the
happier they sounded. Judging from comments that customers have left on 23andMe's website, Neanderthal pride is a common thing.