It has been more or less accepted that genetic evolution can affect culture and that cultural evolution can affect genetics. But many favour one direction over the other. A recent paper looks at a long sustained period of genetic/cultural co-evolution. (Morgan, Uomini, Rendell, Chouinard-Thuly, Street, et al.; Experimental evidence for the co-evolution of hominin tool-making teaching and language. Nature Communications 6, 2015). The paper is a ScienceDaily item (here ).

Early homo species, our ancestors Homo habilis and Australopithecus garhi, used stone tools for two and a half million years. Through the first 700,000 years the tools, called Oldowan, remained unchanged. The researches show that stone-knapping is not easy to learn. The lack of any improvements to the Oldowan tools probably was because language would have been required to teach more sophisticated techniques. After this long period, about 1.8 million years ago, a new set of stone tools appeared, called the Acheulean, that were more technologically challenging. The researchers show that this knapping skill would have needed language to learn from a master.

The researchers set up learning chains where one person was shown and taught a particular knappng skill. That person then taught another and the skill was passed down a chain of learners. Various teaching techniques were used in the chains. It was found that language was needed to learn some skills successfully. Thus they suggest that the Acheulean improvements to tools were due to the start of proto-languages and that knapping and language evolved together. The driving evolutionary pressure was the advantage of better tools.

This picture is very different from the ‘history of language’ put forward by Chomsky. First because the process is seen as long and gradual. Second because it is basically developed as a teaching aid, a form of communication. “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. 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.”

Here is the abstract: “Hominin reliance on Oldowan stone tools—which appear from 2.5 mya and are believed to have been socially transmitted—has been hypothesized to have led to the evolution of teaching and language. Here we present an experiment investigating the efficacy of transmission of Oldowan tool-making skills along chains of adult human participants (N=184) using five different transmission mechanisms. Across six measures, transmission improves with teaching, and particularly with language, but not with imitation or emulation. Our results support the hypothesis that hominin reliance on stone tool-making generated selection for teaching and language, and imply that (i) low-fidelity social transmission, such as imitation/emulation, may have contributed to the ~700,000 year stasis of the Oldowan technocomplex, and (ii) teaching or proto-language may have been pre-requisites for the appearance of Acheulean technology. This work supports a gradual evolution of language, with simple symbolic communication preceding behavioural modernity by hundreds of thousands of years.”