Chemical dating methods
[but] if you haven’t got organic pigment in there, you can’t use radiocarbon and you’d be destroying the art, which is very valuable.To take a normal radiocarbon sample would be unduly disruptive,’ he explains.A huge development in the story of humans is ‘modern’ behaviour, or acting like a human as opposed to acting like a two-legged ape – but it’s hard to date.For example, it’s difficult to say exactly when people started to think abstract thoughts or speak to communicate.A portion of the carbon is the radioactive isotope carbon-14.At death, the exchange stops, and the carbon-14 then decays with a known half-life, which enables scientists to calculate the time of death.Instead, Pike’s team turned to uranium-series dating, another radiometric method.
Like we recognise art as quintessentially human, we also consider tool use and technological progress to be defining for our species, and it was as important to ancient humans as it is to us.‘We’re kind of at the mercy of geochemistry.’Pike’s team used this method to give a minimum date to red hand stencils found in a cave in northern Spain called El Castillo, which contains the oldest known cave art in the world. This is long after humans were supposed to become anatomically modern, adding to the evidence suggesting that early anatomically modern humans didn’t necessarily act modern. Anatomically modern humans arrived in northern Spain around 42,000 to 43,000 years ago, and Neanderthals died out between 39,000 and 41,000 years ago.But because the stencil date is a minimum age, there’s a chance the Neanderthals could have been the artists.‘As it formed on top of the painting, it therefore gives you a minimum age of the painting,’ Pike says.This isn’t ideal, but it’s currently the best tool.