An ancient piece of string dating from 40,000 years ago could put to rest the idea that Neanderthals were grunting, stupid cousins of ancient humans.
The tiny piece of twine found on a flake of flint in the south of France proves that Neanderthals knew how to make fibres from plants.
It was made from the fibrous interior of a tree, and is thought to be the oldest known evidence of textile making.
The researchers write that the find proves "it is difficult to see how we can regard Neanderthals as anything other than the cognitive equals of modern humans."
An international team, including researchers from the Centre National de la Recherche Scientifique (CNRS) in Paris, discovered the cord on a flint fragment from the prehistoric site of Abri du Maras in the south of France.
Over the last two years they have been using microscopic analysis to show that these remains had been intertwined - proof it had been put together by humans.
Photographs revealed three bundles of twisted fibres, plied together to create one cord. In addition, analysis revealed that these strands were made of cellulose, probably from the inside of coniferous trees.
Dr Marie-Hélène Moncel, director of research at the National Museum of Natural History in Paris, said: "We were able to uncover details about these fibres and we observed that they're different, twisted fibres. It was not possible in nature to find this kind of fibre.
"Now we are sure that these twisted fibres are not due to a natural process.
"We can imagine that this twisted fibres could be the remains of a cord of something you could use it for making bags."
Dr Moncel said that knowing enough to harvest the fibres would have required advanced knowledge of the plants in their environment.
She said: "Neanderthals are different but had the same capabilities. He was able to survive in different climates and environments for a long time.
"It's not surprising for me that Neanderthal is able to use the plant world.
"Now we have a lot of information about the mineral world and stone tools because that's whats preserved at Neanderthal sites but we are starting to see that the plant world was a large part of their world.
"In my opinion, different things can be related to this discovery; obviously the ability to make cord but also a huge knowledge about the trees and different parts of trees.
"They had a huge knowledge about the vegetation around the site and the clever behaviour to use everything around the site - the plants, the trees, and to use these different parts of the environment."
"The cord fragment from Abri du Maras is the oldest direct evidence of fibre technology to date.