Reconstructing the relationship between modern humans and Neanderthals

Reconstructing the relationship between modern humans and Neanderthals

Klaus Wilhelm / Max Planck Society

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5 scientistsarAn impressive sight to behold: even though Jean-Jacques Hublin has been studying Neanderthals for many years, their physiognomy still inspires him with awe. Credit: Anna Schroll
The Neanderthals and modern humans must have co-existed in Europe for several thousand years. What happened when they encountered each other and how they influenced one another are riveting questions. Jean-Jacques Hublin and his team at the Max Planck Institute for Evolutionary Anthropology in Leipzig are searching for answers to them. In the process, they have found clues as to what the Neanderthals learned from Homo sapiens—and what they didn't.
Nobody knows what the baby died of. An infection? Attacked by a wild animal? A congenital disease? Perhaps. In any case, the parents left the child behind in a cave in central France, which prehistorians today call the Grotte du Renne. It's even possible that the parents buried their baby in mourning.

Time travel: At the Max Planck Institute for Evolutionary Anthropology in Leipzig, the Human Evolution Department headed by Jean-Jacques Hublin conducts research into human prehistory, paleoanthropology. Postdoc Frido Welker prepares bone fragments, some of them splinters, from the Grotte du Renne. Such fragments had previously seemed to be of no use to experts. Or to put it more accurately, paleoanthropologists such as Welker had no procedures for extracting insights from such damaged witnesses of prehistory.

Thanks to so-called paleoproteomics, this has now changed. This method can detect even the minutest traces of proteins in ancient bone material and reveal information about the identity of the living being from which it stems—a 'pretty revolutionary method,' as Jean-Jacques Hublin says. Proteins survive ten times longer than DNA in ancient bone material. Examination of the genome was previously regarded as the standard method of assigning a bone to a certain animal. Paleoproteomics could take over this mantle from DNA analysis. 'The proteins of Stone Age bones contain valuable information on the phylogenesis and lifestyle of these people,' Welker explains.

It transpired the baby from the Grotte du Renne was a little Neanderthal girl, not even weaned, perhaps six months to two years old on the day she died 44,000 to 40,000 years ago. Her meager remains shed more light than ever before on a dispute in the paleoanthropological world of experts that has been going on for decades. This genre of research is marked in some cases by heated debate. For example, on the question of how Neanderthals and 'modern humans'—meaning you and me—encountered each other in Europe roughly 45,000 years ago. 'There was a cultural transfer between the two hominids,' states Jean-Jacques Hublin with conviction, following the latest high-tech examinations carried out by his team. 'It was only when Homo sapiens arrived that the Neanderthals suddenly began to do things they had never done before.'

The Leipzig-based scientist assumes that 'there was no need of any particularly intensive contact' for this exchange. Let alone any love affair between Homo sapiens and Homo neanderthalensis, as was widely propagated in past years. 'There are too many stories invented,' says the Frenchman. 'It's highly likely that the truth was anything but romantic.'

The witnesses to this past dating back millennia to millions of years—bones, teeth and cultural objects such as tools or jewellery—are limited. They often lead to acrimonious discussions. 'Of course I find that irritating', Hublin says, 'We would be well advised to distinguish between fact and fiction.'

The world was almost devoid of humans in the Stone Age

Let us look at the subject of Homo sapiens and Neanderthals, therefore, in this light, one of the Max Planck scientist's specialist areas. Ever since the first bones of this hominid were discovered in the Neander Valley near Düsseldorf in 1856, legends have been woven around his existence. Primarily because he looks so different from modern humans.

Standing at no more than 1.70 meters, they were not particularly tall; but their physique was strong and powerful with a very prominent chest, the males weighing up to 90 kilos. 'Very impressive,' says Jean-Jacques Hublin as he gazes at the sculpture of a Neanderthal head in his office. It was fashioned at the beginning of the 20th century but is still essentially in line with current knowledge. This means that the face is large and elongated with striking ridges over the eyebrows while the nose is voluminous, the jaw massive and the chin somewhat receding. 'Were you to meet a Neanderthal in the train,' the paleoanthropologist explains, 'you would change compartments.'

Even 45,000 years ago, it must have been a highly unusual event when members of modern man Homo sapiens first came across members of Homo neanderthalensis in the forests and meadows of Europe. 'For both sides,' Hublin says laughing. According to the results of recent studies, the Neanderthals could already look back on at least 400,000 years on the continent—in an area ranging from Spain to the Russian Altai Mountains and up to the latitudes of North Germany.

As hunters and gatherers, they probably wandered in groups numbering no more than 50 to 60 men and women across stretches of land measuring many thousands of square kilometers. They were able to kill even large animals such as bison and horses with great efficiency. They also consumed plants and vegetables to a much larger extent than previously believed. And Neanderthals probably lived at a faster rate. Hublin's team determined the age of a Neanderthal child from wafer-thin layers of enamel on its teeth. It emerged that the children of this hominid matured one to two years earlier than the offspring of modern humans.

Their winters were brutal and long. It's likely that many of their small groups simply died out in long phases of starvation and were replaced by new members. Even in times of their widest distribution, there were probably no more than an estimated 10,000 'Neanderthal Europeans'. 'The Stone Age was an empty world,' Hublin says. According to the latest studies, Neanderthals faced this lonely existence with mental faculties that were almost as sophisticated as those of their cousin and (future) adversary. 'They were more complex than we had long assumed,' the researcher concedes. And furthermore: 'Both hominids were almost identical at this time in terms of their cognitive powers, definitely not ape-like but also not like us.

Homo sapiens brought with him a superior mind

From a technical standpoint, the Neanderthals were definitely skilled, as evidenced by the intricate spears they made even in their early days. They even developed a tool culture roughly 120,000 years ago—or 'industry' as paleoanthropologists say—which characterized a whole epoch: the Mousterian. During this period, they produced tools like arrow points, scrapers, scratchers and blades which were hewn from stones in a characteristic fashion. Explorers have found artifacts from this culture in many archaeological sites—for example, in the before-mentioned Grotte du Renne in Burgundy.

The Neanderthals thus coped very well with the adverse conditions in Europe. They would doubtless have survived for further tens of thousands of years if another species had not suddenly created a stir in Europe 45,000 years ago: modern humans. The new arrivals were much more delicately built than the established species. But the main thing was that they brought with them a mind that was ultimately superior. Homo sapiens not only worked stones but also fashioned fishhooks from fish bones, made jewellery from bones, snails and egg-shells, and formed points for arrows and harpoons. No sooner had they arrived in Europe than they created their very own industry—this period is referred to as the Aurignacian. It is typified by projectile points made from ivory and bones, which at the time were top in hunting technology.

The oldest bones bearing testimony to modern humans are to be found in North Italy, and soon they were scouring areas east of the Rhine in Baden-Württemberg, not far from the Grotte du Renne. The roof of this cave collapsed around 20,000 years ago burying everything beneath it. A stroke of luck for archaeologists who have been uncovering rich finds from the various layers of the buried cave for decades. The cave was clearly a popular place of refuge during the Stone Age. People were continually stopping by. Besides the Mousterian artifacts in the deeper, older excavation layers, archaeologists also hit upon remains of the Aurignacian industry in the upper, more recent layers.

In an intermediate layer, relics of the Châtelperronian (CP) culture were found in the Grotte du Renne—and at further sites with deposits. Many rings, pendants and clasps of ivory, antlers and other materials were found in the 1950s. Earrings, perforated, grooved teeth used as decorative pendants, fossils, and so on. Points or knives with a rounded, blunted back are also very typical. These elaborately worked utensils are sometimes strongly reminiscent of the following Aurignacian industry of Homo sapiens. And not of the Neanderthals.

At the same time, however, easily identifiable remains of bones and teeth were found in the CP layer of the Grotte du Renne—from Neanderthals, as a study from the 1990s suggested. However, this sparked renewed debate. In 2010, British researchers believed they had proved that there were age differences between the various finds from the Châtelperronian layer. They interpreted their findings to mean that the jewellery had been made by modern man and only subsequently mixed up with the Neanderthal relics when the lower layers were disturbed.

Jean-Jacques Hublin was disinclined to believe this, and together with international partners he embarked on a series of tests lasting several years. First, his team selected 40 well-preserved bone samples from the Grotte du Renne—mostly from areas containing the CP jewellery or Neanderthal remains, and less frequently from Mousterian or Aurignacian layers. In addition, the researchers examined the shin-bone of a Neanderthal from a different, well-known French excavation site in Saint-Césaire.

The scientists extracted collagen from the bone samples, an organic component of the connective tissue, consisting of protein chains. Then came the hour of modern analytical equipment. 'I am obsessed with technology,' Hublin says, smiling. For example, there are half a dozen of the latest mass spectrometers in his department—on the one hand, high-tech scales that measure the mass of atoms and molecules, and on the other, accelerator mass spectrometers that can determine the exact age of bones, for example, by using the decay of various hydrogen isotopes in molecules.