That would explain the "stencil" images, but not the "print" images, which the article says exist. This other article says digits are missing only for stencil images (in European cave art) and posits that folding digits was some sort of code: https://www.newscientist.com/article/mg25734300-900-cave-pai... https://news.ycombinator.com/item?id=38769396