Complex cognition shaped the Stone Age hand axe, study shows

By Carol Clark | eScienceCommons | April 17, 2015

The ability to make a Lower Paleolithic hand axe depends on complex cognitive control by the prefrontal cortex, including the “central executive” function of working memory, a new study finds. 

PLOS ONE published the results, which knock another chip off theories that Stone Age hand axes are simple tools that don’t involve higher-order executive function of the brain.

“For the first time, we’ve showed a relationship between the degree of prefrontal brain activity, the ability to make technological judgments, and success in actually making stone tools,” says Dietrich Stout, an experimental archeologist at Emory University and the leader of the study. “The findings are relevant to ongoing debates about the origins of modern human cognition, and the role of technological and social complexity in brain evolution across species.”

The skill of making a prehistoric hand axe is “more complicated and nuanced than many people realize,” Stout says. “It’s not just a bunch of ape-men banging rocks together. We should have respect for Stone Age tool makers.”

The study’s co-authors include Bruce Bradley of the University of Exeter in England, Thierry Chaminade of Aix-Marseille University in France; and Erin Hecht and Nada Khreisheh of Emory University.

Stone tools – shaped by striking a stone “core” with a piece of bone, antler, or another stone – provide some of the most abundant evidence of human behavioral change over time. Simple Oldowan stone flakes are the earliest known tools, dating back 2.6 million years. The Late Acheulean hand axe goes back 500,000 years. While it’s relatively easy to learn to make an Oldowan flake, the Acheulean hand axe is harder to master, due to its lens-shaped core tapering down to symmetrical edges.

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