Humans made advanced stone tools 71,000 years ago



London: Scientists have found evidence for an advanced Stone Age technology dated to 71,000 years ago at Pinnacle Point near Mossel Bay, on the southern coast of South Africa.

This technology, allowing projectiles to be thrown at greater distance and killing power, takes hold in other regions of Africa and Eurasia about 20,000 years ago.

When combined with other findings of advanced technologies and evidence for early symbolic behaviour from this region, the research documents a persistent pattern of behavioural complexity that might signal modern humans evolved in this coastal location.

“Every time we excavate a new site in coastal South Africa with advanced field techniques, we discover new and surprising results that push back in time the evidence for uniquely human behaviours,” said co-author Curtis Marean, project director and Arizona State University professor in the Institute of Human Origins, a research center of the College of Liberal Arts and Sciences in the School of Human Evolution and Social Change.

The reported technology focused on the careful production of long, thin blades of stone that were then blunted (called “backing”) on one edge so that they could be glued into slots carved in wood or bone. This created light armaments for use as projectiles, either as arrows in bow and arrow technology, or more likely as spear throwers (atlatls).

These provide a significant advantage over hand cast spears, so when faced with a fierce buffalo (or competing human), having a projectile weapon of this type increases the killing reach of the hunter and lowers the risk of injury. The stone used to produce these special blades was carefully transformed for easier flaking by a complex process called “heat treatment,” a technological advance also appearing early in coastal South Africa and reported by the same research team in 2009.

The site where this technology was discovered is called Pinnacle Point 5-6 (PP5-6). This spectacular site preserves about 14 meters of archaeological sediment dating from approximately 90,000 to 50,000 years ago.

The documentation of the age and span of the technology was made possible by an unprecedented fieldwork commitment of nine, two-month seasons (funded by the National Science Foundation and Hyde Family Foundation) where every observed item related to human behavior was plotted directly to a computer using a “total station.”

A total station is a surveying instrument that digitally captures points where items are found to create a 3D model of the excavation. Almost 200,000 finds have been plotted to date, and excavations continue. This was joined to over 75 optically stimulated luminescence dates by project geochronologist Zenobia Jacobs at the University of Wollongong (Australia), creating the highest resolution stone-age sequence from this time span.

These findings were reported in the latest issue of the journal Nature.

ANI