Neanderthal artists made oldest-known cave paintings

Neanderthals painted caves in what is now Spain before their cousins, Homo sapiens, even arrived in Europe, according to research published today in Science. The finding suggests that the extinct hominids, once assumed to be intellectually inferior to humans, may have been artists with complex beliefs.

Ladder-like shapes, dots and handprints were painted and stenciled deep in caves at three sites in Spain. Their precise meaning may forever be unknowable, says Alistair Pike, an archaeologist at the University of Southampton, UK, who co-authored the study, but they were almost certainly meaningful to our lost kin. “It wasn’t simply decorating your living space,” Pike says. “People were making journeys into the darkness.”

Humans are thought to have arrived in Europe from Africa around 40,000–45,000 years ago. The three caves in different parts of Spain yielded artworks that are at least 65,000 years old, according to uranium-thorium dating of calcium carbonate that had formed on top of the art.

These mineral deposits develop slowly, as water containing calcium comes into contact with cave surfaces. The water also contains trace levels of uranium from the rock. After the calcium carbonate has precipitated out of the water, a clock of sorts begins to tick, as uranium decays into thorium at a steady, known rate.

Uranium-thorium dating has been used in geology for decades, but has seldom been employed to estimate the age of cave art. Some archaeologists are sceptical of the approach. They suggest that the calcium carbonate could have dissolved and re-crystallized after it was first formed — a process that could have also washed away some uranium, making a sample of the mineral appear older than it is.

Until now, the oldest known cave art was roughly 40,000 years old — stenciled hands and animals in an Indonesian site that was dated in 2014, and discs and hand stencils from a cave in Cantabria, Spain, that were found by Pike and his colleagues in 2012.

Drawing conclusions

Anticipating objections about its dating method, Pike’s team collected samples from the outer, middle and inner layers of the calcium carbonate crust and dated them separately. As they expected, the inner samples closest to the art yielded the oldest dates, and the outer samples had younger dates because they would have been later layers of precipitate. “We can’t think of any processes that would re-crystalize the calcite and still keep them in stratigraphic order,” Pike says. The researchers waited three years to publish their results after finding their first clearly pre-human date so they could collect multiple examples and publish their methodology.