Archaeologists surveying the Kenyan Rift Valley area quite accidentally discovered what are perhaps the oldest known stone tools in the world. They date back about 3.3 million years ago, which would make them at least 700,000 years older than what were formerly the oldest stone tools – discovered in the Ethiopian region of Hadar. So old are the most recent discoveries, that in fact they are precursors of even the earliest fossilized skulls we have of our own genus, Homo, by about half a million years. This is the exciting part. Although we’d like to think that Homo was the first to craft tools – it was actually the work of a more primitive and distant ancestor that we share.
The ancient tools might never have been discovered were it not for a happy accident. Sonia Harmand from Stony Brook University and her team were on their way to a previously uncovered fossil site at the western shore of Lake Turkana on one particular morning in July of 2011. However, the group made a wrong turn and ended up near what was then an uncharted formation of rock. The researchers quickly decided that it was an ideal enough place to harbor artifacts, decided to survey it and by the afternoon, they discovered what they were looking for. The site has been named Lomekwi 3, and giving a closer look, they managed to uncover dozens of stone age tools— including the leftover flakes from cut minerals, as well as cores and even anvils, which were discovered both at the surface, as well as below the ground. Harmand first described her team’s findings on April 14 when giving a lecture during the annual meeting of the Paleoanthropology Society in San Francisco.
“The cores and flakes we recovered are clearly knapped and are not the result of accidental or natural rock fracture,” Harmand said. “The Lomekwi 3 knappers were able to deliver sufficient intentional force to detach repeatedly series of adjacent and superposed flakes and then to continue knapping by rotating the cores.” The team was able determined the age of the tools using a relative dating technique, analyzing the area in which they had been found, between what were two layers of volcanic ash as well as a magnetic reversal of the known ages – due to the nature of continental drift and the Earth’s rotation, magnetic fields change polarity over time, and knowing these periods can help determine the age of the materials.
Another surprising feature of the Lomekwi 3 tools is that they are unusually large – much larger than the stone tools that were excavated in Ethiopia that had previously set the record for the oldest known tools, and they are in fact even larger than the rocks typically used by chimpanzees to crack apart nuts and shells, pointing to a unique transitional period in hominid technology. As described by Harmand, these preliminary observations could indicate that the Lomekwi toolmakers deliberately sought out the biggest, heaviest blocks made out of very hard raw material from local sources despite the availability of smaller blocks. They then applied a number of knapping techniques in order to remove some of the sharper edged flakes away from the core of the rocks. While the chimps, who we share a common ancestor with (and several primate species long deceased,) have been known to go on hunts, the exact purpose of the Lomekwi tools is still unclear. Chimps have been known to use spear-like objects, but the size and weight of the tools suggest another purpose.
Animal bones of the same period have been recovered from the site, perhaps conjuring up images of the ape in 2001: Space Odyssey, who realized he could use bleached tapir bones as a weapon. However, they contain no markings to indicate human activity. Evidence from another site, however, dating to the time of the tools does suggest that hominins (the group in which we, H. sapiens and our extinct relatives all fall into) were already butchering animals for food.
Back in 2010, researchers working at the dig site of Dikika, also in Ethiopia, (where the remains of Australopithecus afarensis, the three-million year-old species to which Lucy belonged, had once been uncovered), made the announcement that they had unearthed 3.4 million-year-old animal bones which showed distinctive marks, knife scrapings from where the hominins had sliced away morsels of meat from the bone with their stone tools. The claim didn’t go without a rather heated debate. Some skeptics refuted the discovery with the suggestion that any alleged cut marks were actually due to these bones being cut and trampled by the feet of passing animals. Other researchers countered that the distinct cut marks may actually have been due to the bites of crocodiles scavenging food. Although the latest discovery of tools at the Lomewki site does not necessarily prove nor disprove that hominins were responsible for making marks on the Dikika remains, it certainly is sufficient evidence to maintain that hominins close enough to be contemporaries of the Dikika nomads did in fact create implements that capable of leaving distinct cut marks.
The identity of these Lomekwi knappers remains unknown. If the manufacture of stone tools is exclusive to the Homo genus, then the evidence suggests that they may have evolved significantly earlier than what the fossil record currently suggests. A more likely scenario, however, which Harmand endorses, is that either the Australopithecus or another hominin, Kenyanthropus (which has been found nearby)— both of which have been known to have existed some 3.3 million years ago were responsible for the Lomekwi tools. Whether in fact the Kenyanthropus is actually of a distinct hominin lineage or just another type of Australopithecus still remains a point of contention, however.
Up until this point, the earliest known stone tools were considered to be derived out of the so-called Oldowan toolmaking tradition. The 20th century paleontologist Louis Leakey coined this term when he described some of the first primitive tools discovered at the Olduvai Gorge back in the 1930s. However, Harmand says that these newly discovered tools are actually different in comparison to the early Oldowan discoveries that they deserve a new name: the Lomekwian tradition.