You don't even need a torch to look for cave paintings in the dark: you just need the sound of your own voice. By listening to echoes as they walk through Spanish caves, acoustic archaeologists are unlocking the secrets of underground soundscapes.
Prehistoric cave paintings, as it happens, aren't scattered at random underground. Archaeologists at a series of Spanish caves have found that areas decorated with cave art also have special acoustic properties. In an interview with Nature, Rupert Till mentions a colleague who claims to "locate the paintings in complete darkness by using his voice to gauge the resonance of the spaces". It's like human echolocation — but to find art instead of prey.
Last year, Till and a group of researchers explored the prehistoric art at the Cantabrian Caves in Spain. In this case, they brought along a laptop and a loudspeaker to map the caves' acoustic fingerprints. Preliminary expeditions in the past were more low-tech with just their voices and hands and sometimes a whistle to guide their exploration.
As the cave paintings they found got older, however, they noticed a change in the acoustics. "The oldest paintings, from up to 40,000 years ago — some as simple as dots or handprints — tend to be in small, intimate places where there is less reverberation," Till told Nature. "Perhaps 15,000 to 20,000 years later we get paintings of animals like deer and bison, sometimes overlaid on top of each other, starting to appear in more echoey spaces that are large enough for groups of people to have gathered for rituals."
Along with cave art, our ancestors had made cave music of sorts. Instruments like a flute made of vulture bone and stone bullroarers have also been found underground. The echoing, haunting soundscape of caves produced music that would sound strange to our ears. Do you have one more minute? Listen to French musicologist Iégor Reznikof sing ancient cave music. [Nature] Picture: Screenshot/Rupert Till