Neanderthals vs Humans? German Scientists Bring Fossils into the Computer Age
Researchers in Leipzig are compiling a ground-breaking digital archive of artefacts from around the world. Created to contrast Neanderthals with modern man, the archive could revolutionize their field -- which is exactly why many oppose it.
Visitors are greeted by three skulls with seashells in their eye sockets. On a table behind them, a student completes a detailed drawing of the teeth in a human jaw.
The bone chamber lies behind a simple steel door on the ground floor. Located right next to the delivery entrance of the anatomy institute at Tel Aviv University, what looks like a janitor's storeroom is actually one of the world's largest treasure troves of human history.
Nestled on foam within blue storage drawers are all sorts of crumbling bones, including arm bones, leg bones, wrist bones, ribs, jaw bones, children's skulls and a range of teeth. These are one-of-a-kind fossils that reveal a key episode in the history of the human species.
Paleoanthropologists have excavated the bones of some three dozen individuals from the rocks in caves in northern Israel. What's unique about their find is that the bones come from two different species of man. They indicate that modern man and Neanderthals once lived hardly a stone's throw away from each other.
This raises a number of questions: Did the two cousins live here at the same time? Did they interact? Did the two rivals have their first showdown for world domination right here in the Levant?
Last year's decoding of the Neanderthal's genetic makeup provided strong evidence in support of this thesis. Researchers working under Svante Pääbo, the director of the Department of Genetics at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, found that modern Eurasians inherited a small portion of their DNA sequence from Neanderthals. This suggests that the two species of man must have had sexual intercourse.
What's more, the genetic researchers were also able to narrow down the timeframe of this momentous genetic intermingling. According to their findings, the intercourse took place between 65,000 and 90,000 years after modern man set foot on the Eurasian landmass, presumably on the eastern edge of the Mediterranean.
Scientists are now trying to determine the exact relationship the inhabitants of these Israeli caves had with the forefathers of modern-day Eurasians. In particular, they are examining the fossil remains to see if there are traces of the interaction between the two species.
Jean-Jacques Hublin almost gets sentimental as he gingerly lifts the skull and jaw bones from their drawers. "As far as I'm concerned, they belong -- so to speak -- to my family," says the 57-year-old paleoanthropologist from the Max Planck Institute.
Hublin's experience here in Israel goes back 36 years to when he was a budding scientist. At the time, Hublin says that scientists used a helicopter to hoist massive boulders out of the Qafzeh Cave near Nazareth.
Hublin, who has become one of the leaders in his field, has now returned to Israel in the hope of unlocking the secrets of the finds he once helped to salvage and to aid scientists in deciphering the enigmatic creature known as the Neanderthal.
When Hublin arrived in Israel from Leipzig, the guardians of the treasure trove of fossils regarded him with both awe and suspicion. Of course, they had grown used to having visitors in the form of scholars travelling here from all over the world to inspect the most famous pieces in the collection. But this time was different.
Hublin and his team of researchers didn't arrive with sketch pads and sliding calipers. Instead, their luggage was packed with high-tech devices weighing tons. Their plan was to use a mobile computer tomography machine to make digital images of as many of the fossils as they could.
Hublin predicts that doing so "will fundamentally alter paleoanthropology." Instead of having to travel from museum to museum, researchers could soon be able to examine finds from around the world from their home computers. What's more, the images often even allow them to recognize details that would have escaped notice under the naked eye.
Hublin has already traveled with his equipment to South Africa, Kenya, Morocco, Croatia and Russia to X-ray all the fossils of human ancestors and prehistoric man he could get his hands on. Piece by piece, he is assembling a digital archive of the family history of Homo sapiens.
To show just what the future holds for his field, Hublin crossed the back courtyard of the anatomy institute in Tel Aviv. There, next to the dumpsters, stands a 20-foot (6-meter) container that the Israeli technicians like to smoke behind. The box's exterior gives no hint that it holds a laboratory on prehistoric man unlike any other one in the world.
X-Ray of History
Patrick Schönfeld spends his days in the cramped, frostily air-conditioned chamber inside the container. The system technician's job is to calibrate the tomographs. Through a display panel, he can follow how the X-ray is scanning the slowly spinning fossils. The procedure can last four, six and sometimes up to eight hours.
The software eventually transforms the massive amount of data into an image of the fossil that is accurate to a few thousandths of a millimeter. The original will have long since been back resting in its drawer when the Max Planck researchers are rotating, spinning or turning it over in their virtual-reality laboratory back home in Leipzig. And whenever they want something they can touch for their research, they don't even have to wait 30 minutes before getting a true-to-size plaster replica of it from their ZCorp Spectrum Z510 3-D printer.
However, paleoanthropologists are an argumentative bunch, and not all of Hublin's colleagues have welcomed his vision of digitalized research on prehistoric humans. Israel Hershkovitz, for example, the curator of the collection in Tel Aviv, cannot hide his unease about the project.
Safe-Guarding Fragile Artifacts
Hershkovitz's office desk is surrounded by dozens of skulls. "Each one of them tells a story," he says. The one with the bullet hole in the skullcap, he explains, was an execution on one of Napoleon's besieging soldiers. Another skull was opened by a Stone Age surgeon. "We're guessing that he used beeswax to stop the bleeding," Hershkovitz says.
Indeed, the Israeli anthropologist views his field as a treasure trove of fascinating stories. And he doubts whether the pricey equipment and sophisticated software of the Max Planck researchers are really necessary to unlock them.
Hershkovitz adds that he isn't completely opposed to the project. In a region as volatile as the Middle East, he thinks it is a good thing to create digital copies as a safety precaution. He recalls how researchers have lost irreplaceable items. During World War II, for example, the Chinese collection of precious prehistoric human remains disappeared without a trace. And a unique skeleton of a Stone Age child was lost in the confusion of the civil war in nearby Lebanon.
Hershkovitz says that digitally scanning fragile items could prevent them from getting damaged. After all, he says, there's always another case of a fossil that has to be glued back together because some student was clumsy.
Despite these positive aspects, Hershkovitz insists he is still a fan of the old-school way of doing things. He views the work of his colleagues in Leipzig as "all too virtual."
Indeed, Hershkovitz sees himself as a champion of the archaeologists who have amassed all the treasures in his collection. Most of them have toiled away in the field for years or even decades, Hershkovitz explains, before finally being able to bring home a handful of bones. And now others are supposed to use virtual copies to harvest the scientific fruits of their labor? In Hershkovitz's mind, anthropologists are merely "scavengers who feed off the sweat of archaeologists."
Most importantly, though, the Israeli curator feels uneasy about the influence of his Leipzig-based colleagues. "We have seen the rise of a mega-center of prehistoric man research," Hershkovitz says, and one that is increasingly setting the direction of new trends in paleoanthropology. "Too much power in a single place can be dangerous," he says.
He worries that people who want to work on his fossils might eventually be forced to travel to Leipzig instead of coming to Tel Aviv.
For his part, Hublin has grown used to this kind of resistance. In fact, he is extremely proud of the rapidly rising influence of his institute. "Fifteen years ago," he says, "Leipzig had yet to establish a firm place on the map of paleoanthropology. Today, it's home to what just might be the greatest institute in the world."
It's hardly surprising that this would arouse the envy of Hublin's colleagues -- and all the more so because he is fully aware of the fact that his digitalization project could threaten to shift power relations in his field.
Until now, Hublin says, it was usual to handle fossils from the dawn of mankind "like relics or national treasures." Under these circumstances, curators assumed the role of keepers of the Grail.
In this way, curators were holding on the reins of scientific power. After all, it is vital for researchers to have access to the fossils. "Whoever is denied (this access) will never get anywhere," Hublin says.
A New Era for Research
Indeed, Hublin believes having a virtual fossil archive could herald the end of this system. He sees his work as boosting accessibility to the objects and says curators "are afraid of losing control."
But, the fact remains that it means a new era for research: Now a large number of discoveries will be made with the click of a computer mouse rather than with a hammer on stone.
This new era is currently visible in the Tel Aviv bone chamber, where Max Planck researchers are conducting painstaking detective work to assemble a more and more precisely detailed picture of the Neanderthal.
The powerful, brightly colored canine of a member of the Neanderthal species is rotating on the monitor of Adeline Le Cabec. Its surface is furrowed with grooves and scratches. "That's the result of abrasion," the researcher explains. "I've even seen teeth that were so worn down by use that the nerve was exposed," she adds. "One doesn't even want to imagine how bad that must have hurt."
Carrying with Teeth
Le Cabec says it's rare to find a dental root that is so bulky among modern humans. And the fact that the chin juts out so prominently primarily results from the degeneration of the chewing apparatus.
With the Neanderthals this is all very different. They apparently ground their teeth more, but why? Did he chew on wood? Did he use animal skin to clean his teeth? Did he gnaw on bones?
To answer these questions, Le Cabec scanned more than 400 teeth as part of her doctoral dissertation. These images showed that the teeth -- and particularly the canines and incisors -- were much more firmly grounded in the jawbone than they are in modern humans. She took this as an indication that Neanderthals used these teeth to hold on to things more than modern humans do.
Through a study of the equilibrium organ inside the cranial bone, Max Planck researchers also determined that modern humans and Neanderthals also moved in different ways. The way in which the semicircular canals in the inner ear are curved suggests that the Neanderthals plodded about in a more ponderous manner.
Neanderthals' Hiking Prowess
This hypothesis is supported by yet another finding scientists made in Leipzig: The sponge-like matrix inside the Neanderthal's shinbone has a different structure than that of his modern cousin. To determine how such differences could arise, the scientists had sheep with bent legs hobble along on treadmills. A half an hour every day was enough to alter the bone structure in a perceptible way. This confirmed the researchers' hypothesis that the Neanderthal was a good hiker, but not as good as modern man at sprinting or jumping.
Another, more significant, difference between the species became evident thanks to X-ray analysis: Neanderthals appear to have had a much quicker life cycle.
Researchers came to this conclusion by analyzing the teeth of both species. They can determine a child's age by analyzing the razor-thin layers of enamel. From this, it emerged that young Neanderthals mature and reach adulthood much more quickly -- between two and three years faster -- than modern humans.
A short childhood, an inability to run fast and teeth with a very strong grip: The more his team of researchers look, the more Hublin feels confirmed in his suspicion that the similarities between the two types of men have been exaggerated.
In museums and textbooks, Hublin says, Neanderthals are mostly depicted as a sort of modern man. But Hublin advocates paying closer attention to the differences. For that reason he was bothered by the enthusiastic response given to the news that Neanderthal genes can be found in modern humans.
"People made a stirring love story out of it," he says. But he adds that history teaches that kidnapping and raping human women may have been the origin of this genetic merging.
Hublin argues that many researchers paint an overly harmonious picture of the coexistence of these two rivals. He thinks it was probably modern man that spelled the end of the Neanderthals. But over time Hublin has realized that his opinion is far from popular. "Whenever I say anything like that in public," he says, "I am greeted by enraged protests."
Translated from the German by Josh Ward