Cave paintings in Spain were made by Neanderthals thousands of years before modern humans arrived in Europe. It shows they were capable of symbolic thought and perhaps even language, writes Carl Zimmer
- Published 9.04.18
It's long been an insult to be called a Neanderthal. But the more these elusive, vanished people have been studied, the more respect they've gained among scientists.
This February, a team of researchers offered compelling evidence that Neanderthals bore one of the chief hallmarks of mental sophistication: they could paint cave art. That suggests Neanderthals could think in symbols and may have achieved other milestones not preserved in the fossil record.
"When you have symbols, then you have language," said João Zilhão, an archaeologist at the University of Barcelona and co-author of the new study.
When Neanderthal fossils first came to light in the mid-1800s, researchers were struck by the low, thick brow ridge on their skulls. Later discoveries showed Neanderthals to have brains as big as our own, but bodies that were shorter and stockier.
By the early 1900s, scientists were describing Neanderthals as gorilla-like beasts, an extinct branch of humanity that could not compete with slender, brilliant humans. Yet evidence from both fossils and DNA indicates that Neanderthals and living humans descend from a common ancestor who lived about 6,00,000 years ago. Our own branch probably lived mostly in Africa.
For a few hundred thousand years after the split, the ancestors of living humans left behind such basic tools as stone axes for butchering carcasses and spear blades for hunting. But about 70,000 years ago, humans in Africa began showing signs of more abstract thinking. They coloured and pierced seashells, for example, possibly to wear as jewellery.
Modern humans began expanding from Africa, arriving in Europe roughly 45,000 years ago. By then, they were capable of even more impressive symbolic creations, including ivory carvings and extravagant paintings on cave walls.
Neanderthals disappeared abruptly afterward, about 40,000 years ago, leaving behind a fossil record of their own from Spain to Siberia. Stockier than their African cousins, they appear to have evolved physical adaptations to harsh climates. They made stone tools of their own, which they used to hunt for game, including rhinos and other big mammals. At first, researchers found no clear evidence of symbolic thought in Neanderthals. But in recent years, that picture has begun to change.
Neanderthals could use feathers and bird claws as ornaments, archaeologists found. But some scientists were sceptical about what these findings meant. Neanderthals might have lived near modern humans, after all, and spotted them making things. Neanderthals were smart enough to copy the ornaments, the thinking went - but not enough to invent them.
This debate was fuelled in part by the difficulty in pinning down a date for human fossils and artifacts.
To determine the age of cave paintings, for example, researchers have traditionally relied on radiocarbon dating. But that method only works if the paint contains carbon-bearing ingredients, such as charcoal. Red ocher, by contrast, can't be dated this way. Making matters worse, radiocarbon dating becomes increasingly unreliable beyond about 40,000 years.
Zilhão joined with archaeologists Alistair G.W. Pike of the University of Southampton and Dirk L. Hoffmann, now at the Max Planck Institute for Evolutionary Anthropology in Germany, to see if the prehistory of European art could be brought into sharper focus.
Instead of studying radiocarbon, they would use a different clock to tell time.
As water seeps into caves, it may deposit milky crusts of minerals on the walls known as flowstones. Flowstones contain tiny amounts of uranium, which slowly breaks down into thorium. The older a flowstone gets, the more thorium builds up inside it.
The researchers returned to caves in Spain where ancient paintings had been discovered over the past century. The artists had drawn abstract images on the cave walls, including long lines, patterns of dots, and the outline of a human hand. The team found flowstones covering parts of the artworks and scraped away samples for dating. In three caves, it turned out, some of the art was over 64,000 years old - about 20,000 years earlier than the first evidence of modern humans in Europe.
"They must have been made by Neanderthals," said Pike.
But a second study, which Zilhão and his colleagues published in February in the journal Science Advances, hints that Neanderthals might well have been painting long before 64,000 years ago.
The scientists travelled to a cave on the coast of Spain where Zilhão had earlier discovered shells that had been drilled with holes and painted with ocher.
In 2010, he and his colleagues had used radiocarbon dating to estimate the age of other shells in the same layer of rock at 45,000 to 50,000 years old. That result did not tell the team who made the ornaments. Neanderthals might be responsible, but it was also possible that the earliest modern humans in Europe made them.
And the uncertainties of radiocarbon dating also had left open the possibility that the shells were, in fact, far older.
Zilhão returned to the cave in order to try uranium dating. He and his colleagues discovered a layer of flowstone sitting atop the rock where they had found the shell jewellery. That flowstone turned out to be about 1,15,000 years old. The coloured, pierced shells themselves are probably not much older than that. Up until about 1,18,000 years ago, the cave was flooded, thanks to sea levels.
That finding provides strong evidence that the shells were made by Neanderthals.
The two new studies don't just indicate that Neanderthals could make cave art and jewellery. They also establish that Neanderthals were making these things long before modern humans - a blow to the idea that they simply copied their cousins.
"These results imply that Neanderthals were not apart from these developments," said Zilhão. "For all practical purposes, they were modern humans, too."
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