A recent study which combined the disciplines of archeology, psychology and evolutionary biology has provided evidence for the co-evolution of Stone Age tools and our ability to communicate and teach. The research suggests that in addition to DNA, culture played a large role in shaping evolution.

On the African savanna, two and a half million years ago, ancient hominin’s created fire first stone tools. They chipped glassy rocks into crude knives that could be used to butcher game animals. Over the following 700,000 years the technology spread across the continent but did not advance much. Roughly 1.8 million years ago million years ago tool technology leapt forward and, according to researchers from from UC Berkeley, the University of Liverpool and the University of St. Andrews, early proto-language emerged at about the same time.

“Our findings suggest that stone tools weren’t just a product of human evolution, but actually drove it as well, creating the evolutionary advantage necessary for the development of modern human communication and teaching,” said Thomas Morgan, postdoctoral researcher in psychology at UC Berkeley, in a statement. Morgan is lead author of the study which was published January 13 in the journal Nature Communications.

“Our data show this process was ongoing two and a half million years ago, which allows us to consider a very drawn-out and gradual evolution of the modern human capacity for language and suggests simple ‘proto-languages’ might be older than we previously thought,” Morgan added.

Along with University of Liverpool archeologist Natalie Uomini conducted a series of experiments involving the teaching of “Oldowan stone-knapping.” The technique involves hammering glassy rocks such as basalt or flint with a hard rock, chipping flakes away to form the blade.

The researchers tested five different ways to teach the skills to 180 students. The students were divided into five or 10 member “learning chains” and asked to attempt different methods of teaching and learning. The first member of the chain was given a “napping” demonstration, the raw materials and five minutes to try the technique. They were then asked to teach it to the next person in the chain, who taught it to the next person and so on.

The found that basic verbal instructions showed far better results than other methods including imitation, gestures and non-verbal presentations.

“If someone is trying to learn a skill that has lots of subtlety to it, it helps to engage with a teacher and have them correct you. You learn so much faster when someone is telling you what to do,” said Morgan.

Because Oldowan stone-knapping, which dates back to the Lower Paleolithic period, remained largely unchanged for 700,000 years the researchers do not believe that those who used it possessed language for teaching.

“They were probably not talking. These tools are the only tools they made for 700,000 years. So if people had language, they would have learned faster and developed newer technologies more rapidly,” said Morgan.

The authors of the paper believe that it was improvements in language and communications that kick started the development of Acheulean hand-axes and cleavers some 1.7 million years ago.

“To sustain Acheulean technology, there must have been some kind of teaching, and maybe even a kind of language, going on, even just a simple proto-language using sounds or gestures for ‘yes’ or ‘no,’ or ‘here’ or ‘there’. At some point they reached a threshold level of communication that allowed Acheulean hand axes to start being taught and spread around successfully and that almost certainly involved some sort of teaching and proto-type language,” said Morgan.