Zenobia Jacobs and Richard G. Roberts in American Scientist:
Even by archaeological standards, Blombos Cave is a modestly sized shelter. Yet artifacts recovered from just 13 cubic meters of deposit inside transformed our understanding of when our species developed behavioral attributes we associate with “modern” humans. From this cramped hole in a sandstone cliff on the Southern Cape coast of South Africa, Christopher Henshilwood and his colleagues unearthed evidence of symbolic expression, in the form of abstract designs (carved ochre bars) and personal ornaments (shell beads) at least 70,000 years old. That is more than 35,000 years before anything comparable emerged in Europe.
When these discoveries were first announced earlier this decade, they stood out as extraordinary and provocative—at odds with the prevailing wisdom about the time and place of emergence of symbolic behavior, a trait unique to Homo sapiens . Our modern anatomical features can be traced back almost 200,000 years, based on fossilized remains found in Ethiopia, but the making of the modern mind apparently lagged behind by more than 100,000 years. The remarkable finds at Blombos raised several intriguing questions. What triggered this watershed event in human prehistory? How geographically widespread was it? Did it occur simultaneously elsewhere in sub-Saharan Africa? And what role, if any, did such innovations play in the first steps of the worldwide dispersal of our species?