The discovery of sophisticated stone tools at an archeological site in South Africa has caused a great stir in the study of early human development.

Small blades, called microliths, were unearthed at Pinnacle Point, located about 500 kilometres west of Cape Town, and dated back 71,000 years. The blades — which were created to be thrown or sent through the air as a projectile — matched the kind of killing technology present in other regions of Africa and Eurasia from 20,000 years ago.

The complexity of the lethal tools indicate that early modern humans were much more complex in their cognitive abilities than previously thought.

"Every time we excavate a new site in coastal South Africa…we discover new and surprising results that push back in time the evidence for uniquely human behaviour," said Curtis Marean, project director and a professor at Arizona State University, who co-authored a report on the tools published in the latest issue of Nature.

The microliths are long, thin blades of stone that have been blunted on one edge so that the blades could be glued to slots carved in wood or bone. They could be used as arrows in a bow or at the lethal end of a spear. As well, the stone used to produce the blades was carefully created for easier flaking by a process called "heat treatment."

This type of blade-making method was evident in that part of the world between 60,000 to 65,000 years ago – which means the method was passed on through generations and survived for more than 10,000 years.

"Eleven thousand years of continuity is, in reality, an almost unimaginable time span for people to consistently make tools the same way," noted Marean.

The discovery means the early humans were capable of prioritizing tasks, possessed foresight and had the ability to transmit cultural notions. Being able to produce weapons that kept the hunter at a safe distance meant that the early modern humans had an advantage when they left Africa — easing their migration all over the world.

"When Africans left Africa and entered Neanderthal territory, they had projectiles with greater killing reach [and] higher levels of pro-social behaviour. These two traits were a knockout punch," said Marean.

"This probably laid the foundation for the expansion out of Africa of modern humans and the extinction [of] our sister species, such as Neanderthals."