"Unfortunately, stone toolmaking is not a common skill in the modern world...

"and hence recruitment of expert subjects presents a unique challenge."

From Dietrich Stout, Nicholas Toth, Kathy Schick and Thierry Chaminade, "Neural correlates of Early Stone Age toolmaking: technology, language and cognition in human evolution", Phil. Trans. R. Soc. B 2008 363, doi: 10.1098/rstb.2008.0001, published 12 June 2008

Just goes to show it's hard to find good stone age technologists even with 2.6 million years to develop those skills.