More than a century ago, amateur archaeologists uncovered the skeletons of six people, along with various ceremonial items, inside an Italian cave called Barma Grande. Estimates of when these people died still provoke controversy.
Radiocarbon analyses of one of the skeletons now suggest it dates to around 26,400 to 23,200 years ago, a time when Stone Age artistic and symbolic expressions achieved unprecedented complexity in ancient Europe. Vincenzo Formicola of the University of Pisa in Italy and his colleagues used the dating technique on a toe bone from the skeleton.
The dating technique failed on two other Barma Grande skeletons because they contain low amounts of collagen, the researchers report in the February Current Anthropology. This chief protein constituent of bone is critical for radiocarbon analysis. Mineral contaminants probably seeped into these bones after burial and displaced the collagen, the scientists say.
That problem probably accounts for a potentially misleading result by a prior radiocarbon study, according to Formicola’s group. In that work, another scientific team dated the skeletons to just 15,000 years ago.