PNAS just published a fascinating new study on the evolution of symbolic behavior. It focuses on the engravings at Blombos and Diepkloof and has ramifications for the evolution of language, music, art, etc. A popular summary is here:
Several previous studies have presented speculations on the possible symbolic function of the Blombos and Diepkloof engravings. Some have suggested that they should be regarded as fully-developed symbols pointing to distinct meanings, more or less like written glyphs. This suggestion is, however, not supported by the present study.
The study itself is here:
How did human symbolic behavior evolve? Dating up to about 100,000 y ago, the engraved ochre and ostrich eggshell fragments from the South African Blombos Cave and Diepkloof Rock Shelter provide a unique window into presumed early symbolic traditions of Homo sapiens and how they evolved over a period of more than 30,000 y. Using the engravings as stimuli, we report five experiments which suggest that the engravings evolved adaptively, becoming better-suited for human perception and cognition. More specifically, they became more salient, memorable, reproducible, and expressive of style and human intent. However, they did not become more discriminable over time between or within the two archeological sites. Our observations provide support for an account of the Blombos and Diepkloof engravings as decorations and as socially transmitted cultural traditions. By contrast, there was no clear indication that they served as denotational symbolic signs. Our findings have broad implications for our understanding of early symbolic communication and cognition in H. sapiens .