March 8, 2018

On the cutting-edge of stone-age technology

Analysis suggests early human use of stone tools more complex and varied than thought. 

A major study of sharp-edge stone tools used by human ancestors over a span of 2 million years challenges the conventional perception that stone tool technology advanced in a simple linear progression.

Researchers from Max Planck Institute, University of Pennsylvania, Arizona State University, George Washington University and the University of Wollongong (UOW) analysed more than 19,000 stone flakes from 34 sites in Africa, southwest Asia and western Europe. The artefacts ranged in age from 2 million years old to 12,000 years old.

Their research is published in Nature Ecology & Evolution in a paper titled ‘Two million years of flaking stone and the evolutionary efficiency of stone tool technology’.

The development of flaking stone tools has been used as a way to trace the behavioural and biological evolution of hominins by looking at changes in tool form and in techniques of production. For this study, however, the researchers focused on the fundamental purpose of flaking stone – the production of sharp working edge – and modelled this over evolutionary time to reassess the evolutionary efficiency of stone tool technology.

The researchers found that while our more recent forebears were able to produce tools with higher amounts of cutting-edge, this was accompanied by an increase in the variation of tool edge proportions; that the toolkits of our more recent ancestors included simpler cutting-edge tools similar to those used by much earlier hominins alongside their more advanced blades.

Co-author Dr Sam Lin, a Research Fellow at UOW’s Centre for Archaeological Science, said this increased variability indicates a greater complexity and flexibility in the ways our human ancestors applied stone tool technology under different circumstances.

“This finding challenges existing perceptions that the evolution of stone tool technology lies in the progressive advancement of tool production techniques,” Dr Lin said.

“Instead, here we suggest that changes in stone tool technology over the course of human evolution is characterised by an increased ability for humans to adapt to a wider variety of situations through applying difference technological solutions.”

Dr Lin said that while larger, thicker flakes had less sharp edge relative to tool weight, this also made them good for transport and easier to maintain and reuse – they could be repeatedly resharpened and knapped over time allowing their owners to get a lot more use out of them.

“Looking more closely at a collection of Neanderthal artefacts from 95-45 thousand years ago, we found that the production of cutting-edge is closely related to stone transport and tool maintenance and reuse,” he said.

“For instance, at times Neanderthals made larger and thicker flakes, which are less efficient in tool edge production, but maintained and transported tools more intensively to extend the service time of these stone tools. This suggests that strategies of tool edge production was contingent on other behaviours of using and managing stone resources.

“The increased variability in tool edge production over time therefore indicates increasing complexity in how early humans applied stone tool technology in their interaction with local environments.”

‘Two million years of flaking stone and the evolutionary efficiency of stone tool technology’ by Željko Režek, Harold L. Dibble, Shannon P. McPherron, David R. Braun and Sam C. Lin is published in Nature Ecology & Evolution.