The advanced toolmakers of Olduvai Gorge

Early Stone Age implements were created fit for purpose.

Olduvai Gorge is one of the world's most important sites for human origins research.

Noel Feans / Flickr

By Nick Carne

As far back as the Early Stone Age people were engineering stone tools in complex ways to ensure they were right for the job, according to new research in Tanzania’s famous Olduvai Gorge.

Mechanical testing of raw materials and artefacts by British and Spanish scientists has revealed that Palaeolithic hominins selected different raw materials for different tools based on how sharp, durable and efficient they were.

They made these decisions in conjunction with information about the length of time the tools would be used for and the force with which they could be applied.

This, the researchers say, reveals previously unseen complexity in the design and production of stone tools during this period.

The research, which employed experimental methods more commonly used in modern engineering, was led by anthropologist Alastair Key from the University of Kent, UK, and is described in the journal Royal Society Interface.

Key and colleagues found that hominins preferentially selected quartzite, the sharpest but least durable stone type at Olduvai for flake tools – a technology thought to have been used for expedient, short-lived cutting activities.

Whenever it was available, chert – which was identified as being highly durable and nearly as sharp as quartzite – was favoured for a variety of stone tool types due to its ability to maximise cutting performance over extended tool-use durations.

Other stone types, including highly durable lavas, were available, but their use varied according to factors such as how long a tool was intended to be used for, a tool's potential to create high cutting forces, and the distance hominins had to travel to raw material sources.

Previous research has demonstrated that Early Stone Age populations in Kenya to select highly durable stone types for tools, but Key says the new study is the first to find evidence of cutting-edge sharpness being considered.

“Why Olduvai populations preferentially chose one raw material over another has puzzled archaeologists for more than 60 years,” he says.

“This has been made all the more intriguing given that some stone types, including lavas and quartzite, were always available.

"What we've been able to demonstrate is that our ancestors were making quite complex decisions about which raw materials to use and were doing so in a way that produced tools optimised for specific circumstances.

“Although we knew that later hominin species, including our own, were capable of such decisions, it's amazing to think that populations 1.8 to 1.2 million years ago were also doing so.”

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