Turkana’s Oldest Stone Artifacts Tell a New Tale
Another rock, another tale and today Turkana’s pride as the original home of our foremost forefathers has stretched back in time by more than 700,000 years. An early morning walk by two archeologists and their team of stone-tool hunters on July 9 2011, pushed back the beginning of archaeological record by more than half a million years.
Drs. Sonia Harmand and Jason Lewis were climbing a remote hill near the western shore of Lake Turkana, leading them to the oldest stone artifacts that have dramatically shaken archaeological knowledge.
An hour earlier, the duo and their team had accidently taken the wrong path through a dry riverbed. Anxious but alert, they began navigating their way back to the main channel. Their sixth sense told them that there was something special about this wrong path. They could almost smell the Eureka moment! Paralyzed by curiosity, they decided to spend some time fanning and surveying the patch of craggy outcrops. After one hour of scooping and scratching, they decided it was time to take a tea break. Lo and behold, a local Turkana tribesman Sammy Lokorodi from Nariokotome pointed to them the spot they had travelled thousands of kilometers in searching of.
They had stumbled upon the earliest stone artifacts dating 3.3 million years ago. The discovery of the site named Lomekwi 3 suddenly pushed back the beginning of archaeological record by seven millennia.
Dr. Harmand with Stony Brook University’s Turkana Basin Institute (TBI) and the CNRS in France and Lewis of TBI are co-directors of the West Turkana Archaeological Project team. They could barely hide their joy.
In the 1930s, paleoanthropologists Louis and Mary Leakey unearthed early stone artifacts at Olduvai Gorge in Tanzania, and named them the Oldowan tool culture. In the 1960s, they found hominin fossils that they named: Homo habilis or handy man. Since then, conventional wisdom in human evolutionary studies supposed that the origins of knapping stone tools by our ancestors was linked to the emergence of the genus Homo. The premise was that our lineage alone took the cognitive leap of hitting stones together to strike off sharp flakes to use for cutting and digging, then an evolutionary success.
Over the last few decades, however, as subsequent discoveries pushed back the date for the earliest stone tools to 2.6 million and the earliest fossils attributable to early Homo to only 2.4-2.3 million years. A series of papers published in rapid succession in early 2015 have solidified these ideas into an emerging paradigm shift in paleoanthropology: the fossil record of the genus Homo now extends back to 2.8 Ma in the Ethiopian Afar; cranial and post-cranial diversity in early Homo is much wider than previously thought.
Australopithecus africanus and other Pleistocene hominins, traditionally considered not to have made stone tools, have a human-like trabecular bone pattern in their hand bones consistent with tool use.
The Lomekwi artifacts have confirmed that one group of ancient hominin started knapping stones to make tools long before previously thought. These new archaeological finds have given the Lake Turkana basin yet more fame pilling on the work of the second and third generation of the Leakey family: Richard, Meave and their daughter Louise, and has produced much of the world’s most important fossil evidence for human evolution. The Lomekwi area had already produced the fossil skull of early hominin Kenyanthropus platyops by Meave and her team.
“These oldest tools from Lomekwi shed light on an unexpected and previously unknown period of hominin behavior and can tell us a lot about cognitive development in our ancestors that we can’t understand from fossils alone” said Dr. Harmand, the lead author of the paper published in the journal Nature announcing the discovery. “Our finding finally disproves the long-standing assumption that Homo habilis was the first tool maker,” she added.
The Harmand team found that these tools are unique compared to the ones known from after 2.6 million years. “The stones are much larger than Oldowan tools, and we can see from the scars left on the stones when they were being made that the techniques used were more rudimentary, requiring holding the stone in two hands or resting the stone on an anvil when hitting it with a hammer stone. The gestures involved are reminiscent of those used by chimpanzees when they use stones to break open nuts” said Dr. Harmand. Their study of the Lomekwi artifacts suggests a transitional technological stage between the pounding-oriented stone tool use of a more ancestral hominin and the flaking-oriented knapping behavior of later, Oldowan toolmakers.
The team was also surprised to find that reconstructions of the environment around Lomekwi at 3.3 million years ago, from the associated animal fossils and isotopic analyses of the site’s soil, indicate the area was much more wooded than paleoenvironments associated with later East African artifact sites from after 2.6 million years. “The Lomekwi hominins were most likely not out on a savanna when they knapped these tools,” said Dr. Lewis.
While it is tempting to assume that these earliest artifacts were made by members of our genus Homo, the team urged caution. “Is it extremely rare to be able to pinpoint what fossil species made which stone tools through most of prehistory, unless there was only one hominin species living at the time, or until we find a fossil skeleton still holding a stone tool in its hand,” said Dr. Lewis.
The Lomekwi 3 discovery raises many new challenging questions for paleoanthropologists. What could have caused hominins to start knapping tools at such an early date? “The traditional view was that hominins started knapping to make sharp-edged flakes so they could cut meat off of animal carcasses, and maybe used the cores to break open bones to get at the marrow” Lewis says. “While the Lomekwi knappers certainly created cores and sharp-edged flakes, their size and the battering marks on their surfaces suggest they were doing something different as well, especially if they were in a more wooded environment with access to various plant resources.”
Drs. Harmand and Lewis are helping lead on going experimental work to help reconstruct how the tools were used.
Another unknown is what’s happening archaeologically between 3.3 and 2.6 Ma. “We’ve jumped so far ahead with this discovery, we need to try to connect the dots back to what we know is happening in the early Oldowan,” Harmand said.
The two will continue using their skills and knowledge to talk to the stones of Turkana, which have produced not just fossils of ancestors, but plenty of oil, water and minerals to take care of future generations.
Gregory Akall is a Doctoral Researcher at the Department of Geography, University of Cambridge, UK and Caleb Atemi is a communication consultant and a media trainer.
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