London, Jan 14 (IANS): The world's oldest butchering tools gave evolutionary edge to human communication, suggests a new study, adding that teaching -- and perhaps even a primitive proto-language -- were in place some 1.8 million years ago.

The prehistoric Oldowan tools, the oldest-known cutting devices, came to be a major evolutionary force in the history of humankind, found the team of researchers from University of California, Berkeley (UC Berkeley), the University of Liverpool and the University of St. Andrews -- the last two in Britain.

Two-and-half million years ago, our ancestors in the African savannah crafted rocks into shards that could slice apart a dead gazelle, zebra or other game animal.

Over the next 700,000 years, this butchering technology spread throughout the continent and, it turns out, came to be a major evolutionary force.

"Stone tools were not 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," explained lead researcher Thomas Morgan, post-doctoral researcher in psychology at UC Berkeley.

The team arrived at their conclusions by conducting a series of experiments in teaching contemporary humans the art of "Oldowan stone-knapping".

In this, butchering "flakes" are created by hammering a hard rock against certain volcanic or glassy rocks, like basalt or flint.

Combining the tools of psychology, evolutionary biology and archaeology, scientists found compelling evidence for the co-evolution of early Stone Age slaughtering tools and our ability to communicate and teach -- shedding new light on the power of human culture to shape evolution.

"To sustain the 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'," Morgan noted.

Oldowan stone-knapping dates back to the Lower Paleolithic period in eastern Africa.

It remained largely unchanged for 700,000 years until more sophisticated Acheulean hand-axes and cleavers, which marked the next generation of stone tool technology, came on the scene.

It was practised 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.

The study was reported in the journal Nature Communications.