In our recent paper in Nature we describe the earliest known instance of an abstract drawing. Here we give a bit of background to what the study entailed. Written by Karen L. van Niekerk and Francesco d'Errico... click the link below to read the full article:
https://natureecoevocommunity.nature.com/users/175937-karen-van-niekerk/posts/38511-the-earliest-drawing-sheds-light-on-the-origin-of-symbolism