There are many studies of language learning abilities of primates (mostly chimpanzee, bonobo) and studies of tool use, knowledge transmission and number sense.
Are there studies or documented cases of drawing, any form of abstract graphical representation, use of concrete objects as representatives, symbols for other things not present, hints of ideal shapes such as circles or lines, uses of markings or pebbles for counting, etc ?
The less influenced by trainers and observers, the better.

