My additional comments include: The same symbols are also found in Australia and the Americas, from the oldest rock art and carried forward from that point. Some of the signs definitely occurred in the Neolithic as "Pottery signs", some were definitely being used in Egypt from before the development of Hieroglyphics, and some of them were incorporated into later regular alphabets that continue to be used. Several of these symbols are the same as appear on the Azilian pebbles. This does also connect up with Alexander Marshak's theories about astronomical notations since some of the symbols are associated with such notation (Some of them even greatly resemble later Roman Numerals and they include regular and repeated use of the signs I,V and X)
Many of these symbols are associated with Megalithic culture (eg, cupmarks) and it has been suggested that several signs are tracing shapes which appear to the eyes automatically during drug-induced hallucinations and trance states. In early Europe this has been linked to the use of the Amanita muscaria mushroom: in other areas other drugs must have been substituted.
As far as patterns of diffusion go, the distribution includes both TransAtlantic and TransPacific continuities and both were definitely accomplished facts before the end of the Ice Ages in the Younger Dryas event.
For further information please follow these links: