Question

For decades, archaeologists assumed that Upper Palaeolithic cave paintings were situated deep within subterranean chambers solely for ritualistic seclusion or preservation. However, recent acoustic analyses of caves like Lascaux and Niaux suggest a different primary motivation: early humans selected locations with resonant properties to enhance vocal and instrumental performances. In these chambers, paintings of resonant-bodied animals, such as mammoths and bison, correspond closely with points of high acoustic resonance, whereas quieter alcoves contain few or no paintings. Proponents of this acoustic hypothesis argue that the choice of painting sites was dictated by the sound quality of the space rather than visual isolation. Skeptics, however, point out that many highly resonant chambers lack paintings entirely, and some heavily decorated walls have poor acoustic properties. Furthermore, they note that the concentration of carbon-14 in charcoal pigments indicates that paintings in a single chamber were often created centuries apart, suggesting that the initial selection of a site had little to do with a continuous performance tradition. Thus, while acoustic resonance may have influenced specific choices, it was likely secondary to symbolic and social factors that evolved over generations.

According to the passage, skeptics argue that the initial selection of cave painting sites was not motivated by a continuous performance tradition. Which of the following findings is presented as evidence that directly supports this specific claim?