Paleoanthropologist and rock art researcher Genevieve von Petzinger has studied and codified these ancient markings in caves across Europe. The uniformity of her findings suggest that graphic communication, and the ability to preserve and transmit messages beyond a single moment in time, may be much older than we think.
https://www.youtube.com/watch?v=hJnEQCMA5Sg
An interesting TED talk, once you get past the long waffly introduction. Just jump to 06:40 in the video if you want to avoid the "what we did on our holidays" sort of stuff.
Now then, how well do these 32 symbols in caves correlate with what we find above ground?