Until recently, researchers generally believed that the first signs of modern human culture appeared 40,000 years ago, when anatomically modern humans arrived in Europe. The cave paintings, musical instruments, jewelry and other artwork preserved from this time period, the Upper Paleolithic, indicate that humans were capable of symbolic thinking. Jewelry probably conveyed many aspects of people's social and cultural identities, and most archaeologists agree that personal decoration was one of the most important expressions of modern human culture.

"Personal ornaments are a powerful tool of communication," says Francesco D'Errico at the Institute of the Prehistory and Geology of the Quaternary in Talence, France, one of the team that studied the beads. "They can indicate social or marital status, for example. But you need to have a complex system of language behind that."

D'Errico and Marian Vanhaeren of University College London have now shown that 100,000-year-old perforated shells found in Israel and Algeria were decorative beads. They had also previously found similar shells in the Blombos cave in South Africa dating to about 75,000 years ago.

"Our paper supports the scenario that modern humans in Africa developed behaviors that are considered modern quite early in time, so that in fact these people were probably not just biologically modern but also culturally and cognitively modern, at least to some degree," said d'Errico. "This idea has been postulated before now, but the evidence has been quite scant."

The two researchers and their colleagues searched through museum collections and found bead-like shells from the sites of Skhul, in Israel, and Oued Djebbana, in Algeria. The shells were of the same kind as those found at Blombos. They are perforated in the same place and showed signs of wear, as if they had been strung together.

Moreover the shells have been found so far from the sea -- 200 km in case of Oued Djebbana -- that they must have been intentionally brought there, most likely for beadworking. By studying modern Nassarius shells from Mediterranean beaches, the scientists also determined that shells with single holes in the centre are rare in nature and that Skhul and Djebbana inhabitants must have purposely perforated or deliberately picked out such shells, arguably for symbolic use.

"It's very important to establish the chronology of these modern types of behaviors, and this paper constitutes we think a significant advancement," said d'Errico.

The discovery brings more evidence in support of the idea that modern human behavior and culture developed gradually in Africa following the appearance of anatomically modern humans around 200,000 years ago. This contradicts the conventional archaeological wisdom claiming that a "cultural revolution" happened in Africa or Eurasia just 40,000 years ago.

"That sort of prejudice is being continually eroded with these kinds of discoveries," says Bernard Wood at George Washington University. "But it still raises the question, in order to make holes in beads and to have the need for beads, does that mean you have language?" D'Errico thinks so: "To me [these beads] are very powerful archaeological evidence that these people were able to speak like us."

Sally McBrearty at the University of Connecticut in Storrs explains the appearance of the Upper Paleotilic Cultural Revolution: "In European sites all of these symbolic artefacts appear together in a package. But even one of these things shows the capacity for symbolic communication. You find them all together in Europe because it was many tens of thousands of years after they were invented in Africa."