Thursday, September 12, 2013

Flint Knapping and the Evolution of Human Language

The idea that tool-making and the human capacity for language were linked has been floating around for a while, but a new article in PLoS ONE uses brain imaging to show they really are connected, through the activation of the same lateralized parts of the brain.


Uomini, Natalie Thaïs and Georg Friedrich Meyer (2013) Shared Brain Lateralization Patterns in Language and Acheulean Stone Tool Production: A Functional Transcranial Doppler Ultrasound Study PLoS ONE 8(8): e72693. doi:10.1371/journal.pone.0072693.

They actually hooked flint knappers up to a functional transcranial Doppler Ultrasound machine while they made Acheulean handaxes and, alternately, produced words based on initial letter cues. The latter is evidently an established test for brain lateralization in linguistic production. The two tasks are reported to have produced very similar and highly correlated brain activity as measured by blood flow. If you're wondering why they didn't use one of the better known brain imaging techniques, such as functional MRI, think about the knapping. Most imaging techniques won't work properly if you're whacking away a big nodule of stone. They found some pretty handy knappers. The handaxes are pretty impressive (see Figure 2, but note that the captions of Figures 2 and 3 seem to have been swapped). Don't miss the video of one of the knappers.

The authors suggest that tool making by flint knapping may have played a role in the co-evolution of language, starting with the Acheuleans (Lower Paleolithic). This would be earlier than many of the chronological estimates for the emergence of language, which often rely upon analyses of anatomy and morphology. Overall, the PLoS ONE article is pretty interesting and clever research. I knew there had to be a reason I was studying those chips of stone.

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