November 16, 2012
Human Ancestors Used Stone Tips For Hunting Earlier Than Previously Believed
April Flowers for redOrbit.com - Your Universe Online
A team of anthropologists, led by the University of Toronto, has found evidence that human ancestors used stone tipped weapons for hunting 500,000 years ago. This is 200,000 years earlier than previously thought, according to the new study published in Science.
Hafting, or attaching stone points to spears, was an important advance in hunting weaponry for early humans as hafted tools require more effort and foreplanning to manufacture. A sharp stone point on the end of a spear, however, increases the weapon's killing power, allowing the hunter more regular access to meat. This would have been necessary to fuel the ever-growing brain of our ancestors.
"There is a reason that modern bow-hunters tip their arrows with razor-sharp edges. These cutting tips are extremely lethal when compared to the effects from a sharpened stick. Early humans learned this fact earlier than previously thought," said Benjamin Schoville, from the Institute of Human Origins, a research center of the College of Liberal Arts and Sciences at Arizona State University.
This complex manufacturing also speaks to the mental abilities of the humans of the time.
"It's telling us they're able to collect the appropriate raw materials, they're able to manufacture the right type of stone weapons, they're able to collect wooden shafts, they're able to haft the stone tools to the wooden shaft as a composite technology," Michael Petraglia, a professor of human evolution and prehistory at the University of Oxford told The Guardian. "This is telling us that we're dealing with an ancestor who is very bright."
Hafted spear tips are commonly found in Stone Age archaeological sites dating as far back as 300,000 years ago, according to the AFP news agency. They were also used in the early Middle Pleistocene, a period associated with Homo heidelbergensis and the last common ancestor of modern humans and Neanderthals, according to the new study.
"Rather than being invented twice, or by one group learning from the other, stone-tipped spear technology was in place much earlier," said Schoville. "Although both Neanderthals and humans used stone-tipped spears, this is the first evidence that this technology originated prior to or near the divergence of these two species."
"It now looks like some of the traits that we associate with modern humans and our nearest relatives can be traced further back in our lineage", Wilkins says. "This changes the way we think about early human adaptations and capacities before the origin of our own species."
Before Homo heidelbergensis emerged, Homo erectus was known to have used handheld stones as cutting tools but not spears.
"This is a major innovation, getting into a new ecological niche," said Petraglia.
He added that the new study sheds light on the development of modern human cognition.
"Hominins — both Homo erectus and earlier humans — were into this meat-eating niche and meat-eating is something that is thought to be very important in terms of fuelling a bigger brain," Petraglia told The Guardian's Alok Jha. "In terms of our evolutionary history, that's been going on for millions of years. You have selection for a bigger brain and that's an expensive tissue and that protein from meat is a very important fuel, essentially. If you become a killing machine, using spears, you've come up with a technological solution where you can be reliant on meat-eating constantly. Homo heidelbergensis is known as a big-brained hominid, so having reliable access to meat-eating is important."
Stone tipped weapons are not the only milestones in human evolution that demonstrate the ever-increasing cognitive abilities. Fire, jewelry and art were also extremely important markers.
The earliest evidence of deliberate use of fire for cooking was found in South Africa last year and dated to a million years ago. Jewelry's earliest known examples were found in caves on the slopes of Mount Carmel in Israel. They were dated to about 100,000 years ago and represent an early comprehension of symbolic behavior. Our earliest examples of art are cave paintings, with the oldest being found at 11 distinct locations in Northern Spain. Neanderthals made these paintings, dating to more than 40,800 years ago.
The team, which included scientists from the University of Cape Town and Arizona State University, examined 500,000-year-old stone points from the South African archaeological site of Kathu Pan 1, in the Northern Cape region. They determined that the stone points had functioned as spear tips by comparing wear on the ancient points to damage inflicted on modern experimental points used to spear a springbok carcass target with a calibrated crossbow.
Previous studies in the Middle East and southern Africa have used this method of comparison effectively to study ancient weaponry. The stone points more commonly exhibit certain types of breaks when they are used as tip spears compared to other possible uses.
"The archaeological points have damage that is very similar to replica spear points used in our spearing experiment," says Wilkins. "This type of damage is not easily created through other processes."
"When points are used as spear tips, there is a lot of damage that forms at the tip of the point, and large distinctive fractures form. The damage on these ancient stone spear points is remarkably similar to those produced with our calibrated crossbow experiment, and we demonstrate they are not easily created from other processes," said Kyle Brown, a skilled stone tool replicator from the University of Cape Town.
Peter Beaumont of the McGregor Museum recovered the points during excavations in 1979 — 1980. Using optically stimulated luminescence and U-series/electron spin resonance methods in 2010, a team directed by Chazan reported that the point-bearing deposits at Kathu Pan 1 dated to ~500,000 years ago.