Neanderthals may not have been that different from us, after all.
New evidence reveals that they created the world's oldest known cave paintings and even wore seashells as body ornaments. Both behaviors suggest that they thought symbolically and had an artistic sensibility like modern humans. Two studies published Thursday in the journal Science detail the latest findings.
"Undoubtedly it is showing that Neanderthals were thinking and behaving just like modern humans," Alistair Pike, co-author of the studies and professor of archaeological sciences at the University of Southampton, wrote in an email.
"We should no longer think of them as a different species, just humans in different places," he said.
The new findings of symbolic thinking show that Neanderthals and modern humans were cognitively indistinguishable, the researchers said.
Cave paintings and artifacts like painted seashells have long been regarded as the work of early modern humans, who were thought to have more advanced cognitive abilities than Neanderthals. Dating cave paintings can be a difficult process, and unreliable techniques never allowed for the possibility that these could be the work of Neanderthals.
Until now, that is. A new technique called Uranium-Thorium dating is less destructive, is more accurate and can go back further in time than other methods. U-Th dating looks at the deposits of carbonate on top of the paint, which contain traces of uranium and thorium that indicate when those deposits formed. That allows the researchers to determine an age for what's under the deposits.
The researchers applied this technique to paintings in the La Pasiega, Maltravieso and Ardales caves in Spain, which had never received "robust" dating. The paintings include red and black images of animals, dots, lines, disks and other geometric signs. There also are engravings, hand prints and hand stencils.
Those hand stencils are particularly significant, and not just because they represent the hand size of a Neanderthal.
"A red line, a red dot or even a positive hand print could potentially be made 'accidentally,' " wrote Dirk Hoffmann, lead author of the studies and archaeologist with the Max Planck Institute for Evolutionary Anthropology, in an email.
"Of course, I am sure that this is not the case, since you would still need to bring [in] light and pigment, but one could argue that all you need is some pigment on your hand when you lean against a wall. A hand stencil cannot be explained like that. You have to hold your hand against the wall and the deliberately spray pigment over this. This is why we emphasize the hand stencil."
The dating revealed that the cave art was created more than 64,000 years ago -- 20,000 years before modern humans appeared in what is now considered Europe.
The shells were found in the Cueva de los Aviones, a sea cave in southeastern Spain. They are unique because they are perforated with holes and colored with red and yellow pigment. Others served as containers for the mineral pigments themselves. The pigments were used on the shells but could have also been used for the cave paintings and even as body paint.
The deposit layer containing the shells dated to 115,000 years ago, which is even older than other shells recovered in Africa that were dated to modern humans.
"The standard archaeological interpretation of such finds is that they are body ornaments," Hoffmann said. "Similar finds were made in Africa or the Levant with similar age. In Africa or the Levant, these were made by modern humans, in Spain Neanderthals made them. So in terms of symbolism, early modern humans and Neanderthals were similar."
The researchers are absolutely confident in their dating technique.
"We have spent 10 years refining the technique and have numerous quality controls," Pike said. "The dates respect the growth axis of the deposits we are dating, the oldest closest to the painting, the youngest at the surface."
Once modern humans left Africa and migrated to Europe and other areas, mixing with the Neanderthals would've been inevitable. The researchers believe that the Neanderthals created this artwork on their own, without being influenced by any other population. But it's possible that they exchanged symbolism or that Neanderthals influenced the art and symbolism of modern humans. Modern humans were capable of symbolic behavior, so it "turns the who's copying who debate on its head," Pike said.
"The idea that culture only evolved with modern humans no longer makes sense," Pike said. Hoffmann suggested that Neanderthals now be referred to as "very close cousins" of modern humans.
Is it possible that anyone else may have created the cave paintings?
Pike said it is incredibly doubtful that a population of early modern humans migrated to Europe so early without any other evidence to suggest it.
"We cannot of course rule out that pre-Neanderthal populations made the art," Pike said. "This sounds like a project for the future."
Hoffmann, Pike and their colleagues want to use their new dating technique in more caves in Spain, as well as France and Italy -- and anywhere else Neanderthals are known to lived.
The findings also raise new questions for researchers.
"How far back does symbolic behavior go? Can it be traced to the last common ancestor of modern humans and Neanderthals? This is perhaps where we should be looking," Pike said.
After years of debate, evidence links Neanderthals to oldest cave paintings
A new dating technique was also used on artifacts like seashells