Radioactive!	Volume 54 Number 3, May/June 2001
by Norman Hammond

The areas of the brain activated during toolmaking have undergone the greatest expansion during human evolution over the past 2.5 million years. (Courtesy Kathy Schick) [LARGER IMAGE]

Archaeologist Nicholas Toth of Indiana University had radioactive isotopes injected into his brain while making simple stone tools in an effort to determine the mental processes of the first toolmakers. Toth, who has spent decades replicating the oldest known tools, used an advanced brain imaging technique called Positron Emission Tomography to determine the areas of the brain he uses in making tools, according to a report by Toth and his colleagues in the Journal of Archaeological Science. He struck flakes from stone cores using about half his normal force so as not to jostle his head and impair accurate imaging.

Although the experiment is plagued by limitations of sample size (not every flintknapper is willing to be injected with radiation) and assumes that early hominids used the same neuronal pathways as at least one modern man, the team notes that the areas activated in Toth's brain are precisely those areas that have undergone the greatest expansion during human evolution over the 2.5 million years since the first tools were made in eastern Africa. Did toolmaking action, then, play an important selective role in the emergence of the modern mind? Too soon to tell, but stay tuned for the next episode of the Radioactive Flintknapper.

© 2001 by the Archaeological Institute of America www.archaeology.org/0105/newsbriefs/radioactive.html

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