Finding out when the earliest human species first developed and used stone tools is an important task for anthropologists as it was such an important evolutionary step. It is noteworthy that the expected date of the early stone technology has just shifted tens of thousands of years.
Using a recently introduced type of statistical analysis, researchers estimate the proportion of stone tool artifacts that could potentially lie undiscovered based on what has been excavated so far. This, in turn, gives us clues as to how old the tool scraps we don’t know about yet are likely to be.
These calculations show that ancient hominins used Oldowan’s basic tools 2,617-2,644 million years ago (up to 63,000 years earlier than previous findings suggest), and the slightly more advanced Acheulean tools may have been used 1,815-1,823 million years ago (at least 55,000 years earlier than previously thought).
“Our research provides the best possible estimates for understanding when hominins first produced these types of stone tools,” said Paleolithic archaeologist Alastair Key of the University of Kent in the UK.
“This is important for several reasons, but for me it is at least the most exciting because it highlights that there are probably substantial parts of the artifact record waiting to be discovered.”
The optimal linear estimate (OLE) statistical analysis applied here has already been used to assess how long species lived before extinction, based on the most recent fossils found. The process has proven to be fairly accurate and it was used the other way around in this study.
The oldest stone tools that archaeologists have excavated to date are unlikely to be in fact the oldest ever used – experts believe many have been lost forever, and dating what is found is difficult – but OLE provides a way to extrapolate based on existing artifacts.
While OLE is still an emerging approach in archeology, the researchers behind the new study hope it will be more widely accepted. While the best reference points are still real findings in the field, these physical discoveries don’t tell the full story of what was actually going on millions of years ago.
“The optimal technique for modeling linear estimates was originally developed by myself and a colleague to date with extinction,” said natural scientist David Roberts of the University of Kent.
“It has proven to be a reliable method to infer the timing of species extinction and is based on the timing of the latest observations, so applying it to the earliest observations of archaeological artifacts was another exciting breakthrough.”
Hominins’ ability to cut away stones and use them for specific purposes opened new horizons for these early humans: in terms of what to hunt, what to build, how to work with food and materials, and so on. It has been called a “momentous threshold” in human evolution.
To give you an idea of how long ago we’re talking about, it has been suggested that the first use of stone tools predates the development of opposable thumbs in humanoids: we smashed stones before we could get a grip on anything.
The oldest stone tools ever found date back 3.3 million years and were discovered at the Lomekwi site in Kenya. While there isn’t enough material on this site to perform an OLE analysis, the researchers think the use of stone tools could go back even further than that – although they also admit that their estimates are likely to change as more excavations and discoveries are being made.
“Determining when hominins first produced Lomekwian, Oldowan and Acheulean technologies is vital for multiple ways of investigating human origins,” the researchers write in their published paper.
The research is published in the Journal of Human Evolution