The team found flowstones covering parts of the artwork 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 Dr. Pike.
Wil Roebroeks, an archaeologist at Leiden University who was not involved in the new study, said the evidence was conclusive.” “This constitutes a major breakthrough in the field of human evolution studies,” he said. “Neanderthal authorship of some cave art is a fact.”
Dating flowstones is a big advance on previous techniques for determining the age of cave art, but the technology has one major limitation: it can assign only a minimum age of to cave paintings. Flowstones may have begun forming the day after a painting was finished ? or 10,000 years afterward.
But a second study, which Dr. Zilhao and his colleagues published in the journal Science Advances, hints that Neandertjals might have been painting long before 64,000 years ago.
The scientists traveled to a cave on the coast of Spain where Dr. Zilhao 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.
The colored, pierced shells themselves are probably not much older than that. Up until about 118,000 years ago, the cave was flooded, thanks to higher sea levels.
That findings provides strong evidence that the shells were made by Neanderthals. They were definitely living in Spain 115,000 years ago, while modern humans would not arrive in Europe for another 70,000 years.
The two new studies don’t just indicate that Neanderthals could make cave art and jewelry. They also establish that Neanderthals were making these things long before modern humans ? a blow to the idea that they simply copied their cousins.
The earliest known cave paintings made by modern humans are only about 40,000 years old, while Neanderthal cave art is at least 24,000 years older. The oldest known shell jewelry made by modern humans is about 70,000 years old, but Neanderthals were making it 45,000 years before then.
The new studies raised another intriguing possibility, said Clive Finlayson, director of the Gibraltar Museum: that the capacity for symbolic thought was already present 600,000 years ago in the ancestors of both Neanderthals and modern humans.
He agreed with Dr. Zilhao that the new study supports the idea that Neanderthals used language. Researchers have found that the inner ears of Neanderthals were turned to the frequencies of speech, much like our own.
The cave paintings that Dr. Pike and his colleagues have dated are generally abstract. There's no evidence so far that Neanderthals painted images of lions and other animals.
?But Dr. Pike doesn't think a lack of animal imagery marks a mental deficiency in Neanderthals.
“It could just be that they had a different belief system and didn't think animals were important to depict in deep caves,” he said. “If you have to prepare your pigment and get to a place in the pitch dark to paint a red line, that's as meaningful as someone painting a bison.”
In the past, many researchers have claimed that mental differences between modern humans and Neanderthals were the reason Neanderthal populations vanished. Our own ancestors, it's been argued, could come up with creative solutions for survival.
?The accumulating evidence puts Neanderthals on more equal footing. They evolved physical differences after the split from modern humans, possibly as they adapted to the harsh northern climates where they settled.
?But their culture developed in parallel with that of modern humans in Africa. And their disappearance is not evidence of inferiority, only of the inexorable mechanics of evolution.
“Neanderthals have disappeared. So have Fuegian Indians. So have Greenland Vikings,” said Dr. Zilhao. “Population extinction has been a part of human history forever.”
