Paleontologists said Wednesday they have found small blades in a South African cave proving that Man was an advanced thinker making stone tools 71,000 years ago -- millennia earlier than thought.
The find suggests early humans from Africa had a capacity for complex thought and weapons production that gave them a distinct evolutionary advantage over Neanderthals, say the authors of a study published in Nature.
Scientists agree that our lineage appeared in Africa more than 100,000 years ago, but there is much debate about when Homo sapiens' cultural and cognitive character began resembling that of modern humans.
Small, manufactured blades such as those found in hunting arrows were first thought to have appeared in South Africa between 65,000 and 60,000 years ago.
Now, a team of scientists say they have found much older blades, called microliths and produced by chipping away at heat-treated stone, in a cave near Mossel Bay on South Africa's south coast.
"Our research... shows that microlithic technology originated early in South Africa, evolved over a vast time span (about 11,000 years) and was typically coupled to complex heat treatment," the study authors wrote.
"Advanced technologies in Africa were early and enduring," they said, adding that long absences of tool-use evidence in the palaeontological record are explained by the relatively small number of sites excavated to date, not by an ebb and flow in early Man's technological know-how.
The find is evidence that early modern humans in South Africa had the ability to make complex designs and teach others to copy them, said the researchers.
This would have allowed them to produce tools like arrows with a much longer killing distance than hand-cast spears.
"Microlith-tipped projectile weapons increased hunting success rate, reduced injury from hunting encounters gone wrong, extended the effective range of lethal interpersonal violence," wrote the team.
It would also have conferred "substantive advantages on modern humans as they left Africa and encountered Neanderthals equipped only with hand-cast spears".
Neanderthals lived in parts of Europe, Central Asia and the Middle East for up to 300,000 years but appear to have vanished some 40,000 years ago.
In a comment on the study, also published by Nature, anthropologist Sally McBrearty from the University of Connecticut said humans making the monoliths would have chipped small blades from stone carefully selected for its texture and heat-treated to make it easier to work with.
They would then have retouched the blades into geometric shapes, probably for use in arrows to be shot from bows.
This, in turn, meant the makers would have had to collect other materials such as wood, fibres, feathers, bone and sinew over a period of days, weeks or months, interrupted by other, more urgent tasks.
"The ability to hold and manipulate operations and images of objects in memory, and to execute goal-directed procedures over space and time, is termed executive function and is an essential component of the modern mind," McBrearty wrote.