Scientists announced Wednesday the discovery of the world’s oldest tools - a cache of hammer stones and rudimentary knives about 2.5 million years old - showing that the mysterious pre-human creatures who fashioned these implements were “surprisingly sophisticated” toolmakers.
Working in the Gona valley of Ethiopia, researchers led by Rutgers University anthropologist Sileshi Semaw unearthed 3,000 sharp-edged stone-cutting tools used, perhaps, to sharpen sticks or cut meat, plus battered cobbles that could have been used to crack shells or bones.
The tools push back the origins of technology by at least 250,000 years, the researchers said, deepening the mystery of just who had made these artifacts from fist-sized chunks of volcanic rock. No remains of the toolmakers were found, but the tools appear to be older than the oldest reliably dated remains of the genus from which modern human beings developed.
So it is by no means certain that the world’s first toolmaker was a direct ancestor of modern humanity, experts said. The fossils date from an era when at least two pre-human species roamed the forests and plains of Africa, one of which later became extinct, researchers said.
The Rutgers researchers suggested the tools might have been made by a third, as-yet-undiscovered early species of the genus Homo, the evolutionary group that includes modern humans and their closest extinct relatives.
Nor does anyone know why - roughly 2 million years after the earliest primates first started walking upright - these primitive creatures were inspired to take nature into their hands and invent tools.
“The development of stone tools was a major breakthrough in early human behavioral evolution,” Semaw said. “Prior to this period, we did not find any trace of stone tools and suddenly - boom! - you have thousands and thousands of them. This is an innovation that appeared suddenly.”
“These hominids were as dependent on tools then as we are today,” said Jack Harris, chairman of the Rutgers anthropology department, who collaborated with Semaw. “In a sense, tools are an extension of ourselves, an extension of our body created through our intelligence. Throughout our evolutionary history we have become more and more dependent on technology and tools.”
Harris suggested that changes in Africa’s ancient climate, which at the time was cooling and becoming more arid, may have made food harder to find and forced the hominids to innovate.
Whichever hominid species first mastered the ability to use tools to butcher their prey or sharpen sticks to root for vegetables or dig for water had an enormous advantage over its competitors.
Semaw and his colleagues discovered the tools between 1992 and 1994 at two sites in the arid arroyos of the Ethiopian badlands, sandwiched between layers of volcanic rock and ash that could be precisely dated by the Berkeley Geochronology Center using radio-isotope and paleo-magnetic techniques. The find was the subject of research published today in the journal Nature.
Experts are convinced the flaked rocks are not accidents of nature that animals had used by chance. Although tool-making is considered a distinguishing hallmark of early pre-human species, humans are not the only creatures for whom tool-making comes naturally, even today. Wild chimpanzees for example, use sticks to hammer and threaten, stems to fish for termites, leaves as sponges or umbrellas, and rocks to hammer or hurl.
But the researchers said that it took a much more sophisticated intelligence and a practiced hand to craft the hundreds of flaked knife-like tools found at the Gona Valley sites.
“None of the non-human primates are known to break one rock with another rock to make a sharp-edged implement like these,” Harris said. “That has never been exhibited (by other primates) in the wild.”
Surprisingly, these earliest tool-makers were slow to improve on their invention, making the same tools virtually unchanged for almost a million years.
The chipped stones from the Gona Valley all bear many of the same characteristics of early human manufacture that are typical of tools found in Tanzania, Kenya and Ethiopia, which date from 1.8 million years and 2.35 million years ago. No one knows what species made the tools found at those sites either.
The implements are all examples of a style of primitive tool making called the Oldowan stone tool industry, named for the place at Olduvai Gorge in Tanzania where the late Mary Leakey discovered some of the early artifacts.
MEMO: This sidebar appeared with the story: WHERE ELSE? The tools, almost 3,000 of them, were collected in 1992-94 on two tracts in Gona, near the banks of the Gona River in northern Ethiopia. The site is near the northern tip of the geological crevice called the Rift Valley, which stretches through East Africa and passes near its southern terminus through the Olduvai Gorge in Tanzania, where stone tools dating back 1.8 million years were unearthed in the 1960s. The Gona site is about 10 miles from the spot where, in 1974, archaeologists unearthed the bones of “Lucy,” a female australopithecus afarensis hominid who, at more than 3 million years, is one of the oldest ancestors of the human race found.