Ann Gibbons writes about half-million-year-old blades from the Kapthurin Formation of East Africa:
Now it appears that more than 500,000 years ago, human ancestors living in the Baringo Basin of Kenya collected lava stone cobbles from a riverbed and hammered them in just the right way to produce stone blades. Paleoanthropologists Cara Roure Johnson and Sally McBrearty of the University of Connecticut, Storrs, recently discovered the blades at five sites in the region, including two that date to between 509,000 and 543,000 years ago. "This is the oldest known occurrence of blades," Johnson reported Wednesday here at the annual meeting of the Paleoanthropology Society.
Blades appear occasionally in later Middle Stone Age contexts. The current report is interesting because they are early – but I think the interesting part is that blades were lost so many times. Many archaeologists write about them as if blades were self-evidently superior technology – for instance, the argument that blades “generate more useful sharp edge from the same amount of raw material.”
Of course, if blades were really obviously superior, then we would see more uniformity among Late Pleistocene people, including the Africans who repeatedly pick up the blade production habit and then discard (or more likely, forget) them entirely.