The ability of humans to use language is among the things that make them distinct from other animals, but scientists were not certain as to why and how this trait has evolved. A new study, however, suggests that how language has evolved is directly tied to ancient tool-making.

For a new study published in the journal Nature Communications on Jan. 14, Thomas Morgan from the University of California at Berkeley and colleagues presented evidence that stone tool-making has played a very important role in the evolution of language and teaching among our prehistoric human ancestors.

The first verbal communications, which likely happened 2.5 million years ago, were likely about tool-making.

The study proposes that our human ancestors in the African savannah may have developed a primitive form of language so they could teach each other how to make stone age tools, a crucial skill for survival at the time.

The researchers came up with this conclusion after conducting experiments on teaching the art of Oldowan stone knapping. Starting 2.5 million years ago and for about 700,000 years, the Oldowan stone tools were used to butcher animals. Oldowan stone knapping involved creating butchering flakes by hammering hard rock against basal, flint and other certain types of glassy and volcanic rocks.

By experimenting with five different ways of teaching Oldowan stone knapping skills to over 180 volunteers, Morgan and colleagues found that using spoken communication rather than imitation, gestures or non-verbal presentation, obtains the highest volume and best quality of flakes with least wastage and in the least amount of time.

Morgan explained that if someone tries to learn a new skill that involves a lot of subtlety, he can learn much faster when a teacher tells him what to do and corrects him. For the Oldowan hominins, the researcher said that they were not likely talking given that those were the only tools they produced for 700,000 years. They would have learned faster and were able to come up with newer technologies faster if they had a language.

"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," the researchers wrote.

The demand for Oldowan tools, however, drove the hominins to improve their communication, planting the seeds of language, teaching and learning, which eventually led to the development of the Acheulean hand axes and cleavers about 1.7 million years ago.

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