Surprising level of technical shrewdness required to make Stone Age tools, say archaeologists watching complex flake production

© Norfolk Museums and Archaeology Service

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The craftspeople who made Stone Age hand axes would have required far greater skill than their predecessors needed to create the oldest known tools, according to archaeologists who have concluded that prehistoric practitioners were more than “ape-men banging rocks together”.Recreating Lower Palaeolithic tools by teaching a group to strike stones, researchers examined brain activity during knapping, which was once carried out by skilled prehistoric people using pieces of bone, antler or stone. Magnetic Resonance Imaging showed that the process is “complicated” and “nuanced”, says Dietrich Stout, the experimental archaeologist who led the project.“For the first time, we’ve shown a relationship between the degree of prefrontal brain activity - the ability to make technical judgements - and success in actually making stone tools,” says Stout.“Stone toolmaking is a demanding technical skill that can take years to master. With an average of 167 hours practice over 22 months, our subjects gained competence in flake production but showed less improvement in hand axe making.“This provides a reference point for estimating the learning investments of Paleolithic toolmakers.“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 team said that previous research, suggesting that “considerable forethought” was needed by Palaeolithic people who made hand-axes and wooden spears, was “naïve”, adding that the latest results “offer hope” for new findings about human cognitive evolution.Professor Bruce Bradley, a co-author of the research from the University of Exeter, says the earliest known tools – simple Oldowan stone flakes from 2.6 million years ago – are significantly easier to make than the Archeulean hand axes of 500,000 years ago. Most of the hand axes produced by the archaeologists lacked the “high standards” of the Stone Age tools.“Making an Acheulean hand axe is hard to master due to its complexity and symmetry requiring abstract, sequential strategic thinking,” explains Professor Bradley.“This type of thinking is associated with activity in the prefrontal cortex, which allows one to project what’s going to happen and use this to guide subsequent actions.“Our experiments showed that when monitoring the brains there was increased activity in the prefrontal cortex, showing that making tools requires complicated thinking.”