Neanderthals may have invented a tool that is still in use today

Archaeologists have unearthed the oldest specialised bone tools ever found in Europe, at sites where Neanderthals lived more than 40,000 years ago.

The slender, curved implements called "lissoirs" were shaped from deer ribs and likely used to work animal hides to make them softer, tougher and more waterproof. The tools are remarkable because they seem to pre-date the arrival of modern humans in Europe, suggesting that Neanderthals invented them, rather than copying the designs from humans.

Similar tools, called slickers or burnishers, are still in use by leather workers today, meaning the instruments may be the only known examples of modern tools that owe their existence to our ancient Neanderthal relatives.

"There's a good case to be made for Neanderthals inventing this one aspect of modern human technology," said Shannon McPherron at the Max Planck Institute for Evolutionary Anthropology in Leipzig. "It's the first time we've seen Neanderthals use bone in a way that uses its unique properties."

The tools are said to be "specialised" because they exploit particular features of bone, such as its toughness and flexibility. Lissoirs could not be made from a hard and brittle material like stone, because it would damage the leather and risk snapping in the user's hand. But made from bone, the tool would flex as it was pressed onto a hide.

Researchers led by Marie Soressi at Leiden University found the first large piece of a lissoir at a cave called Pech-de-l'Azé I on a tributary of the Dordogne in southwest France. The skull of a Neanderthal child, ash from a hearth and other Neanderthal remains were found at the same site, but there is no sign that humans ever lived there. The site dates to around 51,000 years ago.

The second group, led by McPherron, unearthed three smaller tips of lissoirs at another Neanderthal site 35km away, beneath a shallow cliff face in Abri Peyrony. Carbon dating revealed that bone at the site was 41,000 to 48,000 years old.

The tools were probably made from the ribs of red deer or reindeer, the authors write in Proceedings of the National Academy of Sciences. The tip of each tool was tapered, ground and rounded off, and one side was polished to a shine. The other side was fresh, unmodified bone. Intact, each tool would have been 20 to 40cm long, Soressi said.

Under the microscope, the tip of the largest tool, around 8cm long, showed signs of wear from being used. The scientists saw similar abrasive marks when they made copies of the tools from fresh animal ribs and used them to smooth out a dry hide. The smaller tips likely broke off when the Neanderthals pressed too hard.

Other bone tools made by Neanderthals have been found before, but the lissoirs are thought to be the first that required a technological leap to exploit the special properties of bone.

"They were taking a rib and probably snapping or grinding the end off it, then grinding the tip into a smooth arch shape. They were then pushing the tip into a hide, and that process of applying firm pressure across the hide makes the leather more pliable and more water resistant. They didn't choose any old bone, they chose ribs which have some give to them. The rib flexes in your hand and doesn't gouge the leather, it polishes it," said McPherron.

The scientists put forward several scenarios to explain the origins of the tools. Fossil evidence suggests that the first wave of modern humans reached Europe with stone and bone tools around 43,000 years ago. But perhaps they arrived much earlier, and Neanderthals learned bone tool skills from them. Another possibility is that the technology spread to Neanderthals in Europe from modern humans who were already in the Middle East. A third is that Neanderthals invented the tools and early modern humans adopted them when they arrived.

Soressi discovered the larger lissoir in 2005, but had to wait for more fragments to be found before she could convince a journal to publish the work. "Neanderthals were able to produce these tools and they have so perfect a design that we are still using them today. What surprises me is to have something that lasts 50,000 years with almost no changes. It's so well adapted to the task," she said.

"This adds to the evidence that Neanderthals were developing their own complexity culturally and brings us back to the question of whether they were doing this on their own, entirely independently, or under the influence of modern humans," said Chris Stringer, head of human origins at the Natural History Museum in London.

"It looks like there weren't modern humans alongside the Neanderthals passing this kind of technology across. But modern humans had made it to the Middle East at this time, and they bred with Neanderthals there, so maybe there could have been exchanges of information that then spread westwards," he said.

Stringer concedes that the Neanderthals might have invented the tools themselves. "They had big brains, complex societies and were skilful toolmakers. They survived under difficult conditions for long periods. The whole image of the Neanderthals being the grunting cavemen is out of the window, and for me has never been an accurate portrayal. They were not stupid."