Two and a half million years ago, our hominin ancestors in the African savanna started flaking off bits of rock sharp enough to easily slice apart a dead gazelle. Over the next 700,000 years, this butchering technology spread throughout the continent, but remained largely unchanged until the more sophisticated Acheulean hand-axes and cleavers – the next generation of stone tool technology – came on the scene.
But how did our ancestors pass on their newly found knowledge? How did their kids pick up the skills they needed to do it themselves? To investigate, researchers from the University of California, Berkeley, the University of Liverpool and the University of St. Andrews asked 180 college students to take part in a sort of game of Chinese whispers.
First, the researchers taught a small group of students the art of Oldowan stone-knapping, a tool-making method in which sharp flakes are knocked off by hitting a hard rock against a volcanic or glassy rock, like basalt or flint.
They then divided the students into five- or 10-member “learning chains”, each using one of five different teaching methods to convey their newly-found skills. These included reverse engineering (where the learner is left alone to figure out how the tool was made), imitiation / emulation (where the learner watches, but there is no effort to help them learn and the “teacher” doesn’t really care), basic teaching (where the pupil is basically just watching, however, the teacher wants them to learn so does things like slow their actions or turn to face the learner to help them out), gestural teaching (where hand movements add to the process) and verbal teaching (where basic words and noises aid the process).
With the head of the chain having received a knapping demonstration, the raw materials and five minutes to try their hand at it, that person then showed it to the next person in the chain, who in turn showed the next person, and so on. The researchers measured the rate of transmission, in an attempt to establish how different teaching methods affected the results.
Perhaps unsurprisingly, the researchers found that the demonstration that used spoken communication yielded the highest volume and quality of flakes in the least amount of time, and with the least waste.
“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,” said Thomas Morgan, lead author of the study and a postdoctoral researcher in psychology at UC Berkeley. “You learn so much faster when someone is telling you what to do.”
“The most basic teaching conditions (imitation and reverse engineering) produced lots of odd behavior – participants learnt so little that they had to invent much of the technique for themselves, sometimes with odd results” Morgan told DigVentures in an email.
“I remember one participant developed a technique where they buried their flint in a “nest” of other rocks with tough fabric woven through it such that the flint was in the middle. They then crushed the nest from various directions. They did not do well, but their pupil watching them do this also built a nest (though much smaller). Nest building disappeared a couple of participants later as I think they realised it wasn’t very effective!”
Oldowan stone-knapping dates back to the Lower Paleolithic period in eastern Africa and was practiced by some of our earliest ancestors, such as Homo habilis and the even older Australopithecus garhi, who walked on two legs, but whose facial features and brain size were closer to those of apes.
What does this mean for the original teachers of Oldowan technology? “They were probably not talking,” said Morgan. “These tools are the only tools they made for 700,000 years. If they had language, they would surely have learned faster and developed newer technologies more rapidly” said Morgan.
Indeed, the data suggests that when the Oldowan stone-tool industry started, it was probably not being actively taught. “Yes, they were learning, but there was probably little if any effort to help the learner, the ‘teacher’ is just being watched as they go about their own self-interested behaviors. We think teaching, in some form, developed across the Oldowan, perhaps along with proto-language” explained Morgan.
“So in the early Oldowan they were definitely learning from each other, but just without teaching. There would have been quite a lot of individual discoveries too as each knapper had to work out a lot of the details of the process themselves because just watching really is not a great way to learn from others”, Morgan explained.
To sustain the next generation of tool-making, Acheulean technology, there must have been a more advanced kind of teaching, and maybe even a kind of language, even just a simple proto-language that uses simple sounds or gestures for ‘yes’ or ‘no,’ or ‘here’ or ‘there’.
“At some point the level of communication 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,” Morgan said.
The study, published in Nature Communications, suggests that communication among our earliest ancestors may be more complex than previously thought, with teaching and perhaps even a primitive proto-language occurring some 1.8 million years ago.
“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 Morgan.
“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.
DigVentures crowdfunds archaeological projects that everyone can be part of, in the UK and overseas. With help from people all over the world, we investigate the past and publish our discoveries online for free. Become a DigVentures Subscriber and be part of great archaeology - all year round!Subscribe