One wrong turn can lead to great discovery, and just a few stones can change ancient history forever.
Sonia Harmand and Jason Lewis, research professors with the Turkana Basin Institute (TBI) and Department of Anthropology at Stony Brook University and co-leaders of the West Turkana Archaeological Project (WTAP), learned that firsthand when they unearthed the earliest stone tools ever found, dated at 3.3 million years old.
Their discovery, at a site named Lomekwi 3 in northern Kenya and published in Nature on May 21, 2015, is a group of stones-turned-tools through a process called “knapping,” in which flakes of stone are chipped away by hand to create a sharp edge. But whose hands created these tools?
The Lomekwi 3 tools predate what archaeologists recently considered to be the oldest stone tools, known as Oldowan artifacts, by 700,000 years — a gap long enough to challenge how we interpret human evolution.
Oldowan artifacts were first discovered in the 1930s by famed paleoanthropologist Louis Leakey at Olduvai Gorge in Tanzania. Leakey and his wife Mary later found bones about as old as those Oldowan tools — 1.8 million years — from a species they named Homo habilis, or “the handy man.”
The confluence of those two Leakey discoveries suggested that stone tool making began with the genus Homo, to which modern humans belong. But the Lomekwi 3 stone tools could smash that theory altogether.
“Many have expected the threshold of stone tool-making to be pushed back in time, but the Lomekwi excavations really do represent a major advance in our understanding,” said Richard Leakey, chair of the TBI and Louis and Mary Leakey’s son. “This is a seminal discovery and publication.”
Finding the Tools
On the morning of July 9, 2011, Harmand and Lewis were on a mission to find early stone tools — a seemingly tough job in the badlands of northern Kenya, where the arid, rocky terrain resembles a roadless New Mexican landscape.
In search of a starting point, specifically the site where in 1999 renowned anthropologist and TBI research professor Meave Leakey discovered a 3.5-million-year-old hominid skull, the WTAP team drove down a dry riverbed along the western shore of Lake Turkana.
But a map mix-up led the international crew of scientists to a dead end — or so they thought. Harmand and Lewis got out and climbed a nearby hill to get their bearings.
“Something was really unique about this place,” said Lewis. “We could tell that this area had a lot of hidden areas just waiting to be explored.”
So for an hour before teatime (a custom in Kenya as much as in Britain), they surveyed the fated location named Lomekwi 3. While it wasn’t Leakey’s skull site, the team spotted a few strange rocks on the surface.
They surveyed around a bit more intensely, and that’s when local Turkana tribesman and WTAP team member Sammy Lokorodi helped spot the oldest stone tools ever discovered, sparking a thorough excavation of the site.
“When we had realized that these tools were knapped by our ancestors, and that they are surely very old, we started to jump for joy,” said Lewis, “and then also thought, ‘Now we have to prove this to the rest of the world.’”
Studying the Tools
The proof is highlighted in the Nature publication, co-authored by an international multidisciplinary team of archaeologists, paleontologists, geologists and paleoanthropologists.
Scientists dated the Lomekwi 3 tools by correlating the layers of rock where they were discovered with well-known radiometrically dated tuffs, a type of porous rock formed from volcanic ash.
Louise Leakey, TBI research professor and daughter of Richard and Meave Leakey, worked with her team at the TBI facility in Kenya to create 3D laser scans of the Lomekwi 3 tools. The scans not only reveal very fine surface details of the tools (important for interpreting how they were used), but also provide digital versions to share with colleagues and the public for further analysis.
Studies conducted by Harmand and her team of world experts in lithic analysis helped to interpret physical features of the tools and reconstruct manufacturing techniques used at Lomekwi 3, including experimental replication of the tools.
“The tools are much larger than later Oldowan tools, and we can see from the scars left on them 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 hammerstone,” said Harmand. “Some of the gestures involved are reminiscent of those used by chimpanzees when they use stones to break open nuts.”
These studies suggest the Lomekwi 3 tools could represent a “technological missing link” between the pounding-oriented stone tool use of a more ancestral hominin and the knapping process consistent with later Oldowan toolmakers.
Because no hominin fossils or cut-marked bones have yet to be found at Lomekwi 3, scientists cannot say who made these tools or how exactly they were used.
“Contrary to popular belief, the really cool discoveries in science aren’t the ones that answer questions,” said John Shea, professor of Anthropology for the TBI. “They are ones, like these stone tools from Lomekwi, that make us ask new questions, questions we had not thought about before.”
Shea posed a few of these questions — Why did early hominins make stone tools at that site and time? How did they use the tools? Why is there such a large gap of time between the Lomekwi and Oldowan tools? Did hominins stop making stone tools, then “reinvent the wheel” later?
It’s up to scientists from entities such as the WTAP, the TBI and Stony Brook University to continue inspiring these questions through discovery, and perhaps dig up a few answers along the way.