OLDEST STONE TOOLS
Marked, cut and smashed fractured animal bone fossils, made by using stone tools, were found in Dikika, Ethiopia 200 meters from the remains of a young Australopithecus afarensis girl who lived about 3.3 million years ago. Unlike 2.5-million-year-old stone flakes found Ethiopia in 1997, which were mostly sharp cutting edges or the remains of the tool-making process, the stone tools that made the marks in Dikika were likely used as they were found. Detailed analysis of the cut marks on the bones seemed to indicate they were significantly different from tooth and claw marks made by predators. One of the marks was embedded with a small fragment of stone, according to a report in the journal, Nature.
Stone tools found from 2011 to 2014 at Lake Turkana in Kenya have been dated to be 3.3 million years old, and predate the genus Homo by half million years (the oldest known Homo fossil is 2.8 million years old). The stone tools may have been made by Australopithecus afarensis who lived 3.9 to 2.9 million years ago. The dest known example of this species is Lucy, which inhabited Ethiopia around the same time as the date of the oldest stone tools. The tools were dated based on the volcanic ash layers near the sediments they were found in. The volcanic layers are dated based on their magnetic signature (whether they pointed north or south due, calibrated using the reversal of the magnetic poles). [Source: Wikipedia]
Charles Q. Choi of Live Science wrote: “Researchers tried using stones to knock off and shape so-called flakes or bladesto better understand how these stone artifacts might have been made. They concluded the techniques used may represent a stage between the pounding used by earlier hominins and the knapping of later toolmakers. "This is a momentous and well-researched discovery," paleoanthropologist Bernard Wood, a professor of human origins at George Washington University, "I have seen some of these artifacts in the flesh, and I am convinced they were fashioned deliberately." Analysis of carbon isotopes in the soil and animal fossils at the site allowed the scientists to reconstruct what the vegetation there used to be like. This led to another surprise — back then, the area was a partially wooded, shrubby environment.” [Source: Charles Q. Choi, Live Science, May 20, 2015 ]
Websites and Resources on Hominins and Human Origins: Smithsonian Human Origins Program humanorigins.si.edu ; Institute of Human Origins iho.asu.edu ; Becoming Human University of Arizona site becominghuman.org ; Talk Origins Index talkorigins.org/origins ; Last updated 2006. Hall of Human Origins American Museum of Natural History amnh.org/exhibitions ; Wikipedia article on Human Evolution Wikipedia ; Human Evolution Images evolution-textbook.org; Hominin Species talkorigins.org ; Paleoanthropology Links talkorigins.org ; Britannica Human Evolution britannica.com ; Human Evolution handprint.com ; National Geographic Map of Human Migrations genographic.nationalgeographic.com ; Humin Origins Washington State University wsu.edu/gened/learn-modules ; University of California Museum of Anthropology ucmp.berkeley.edu; BBC The evolution of man" bbc.co.uk/sn/prehistoric_life; "Bones, Stones and Genes: The Origin of Modern Humans" (Video lecture series). Howard Hughes Medical Institute.; Human Evolution Timeline ArchaeologyInfo.com ; Walking with Cavemen (BBC) bbc.co.uk/sn/prehistoric_life ; PBS Evolution: Humans pbs.org/wgbh/evolution/humans; PBS: Human Evolution Library www.pbs.org/wgbh/evolution/library; Human Evolution: you try it, from PBS pbs.org/wgbh/aso/tryit/evolution; John Hawks' Anthropology Weblog johnhawks.net/ ; New Scientist: Human Evolution newscientist.com/article-topic/human-evolution; Fossil Sites and Organizations: The Paleoanthropology Society paleoanthro.org; Institute of Human Origins (Don Johanson's organization) iho.asu.edu/; The Leakey Foundation leakeyfoundation.org; The Stone Age Institute stoneageinstitute.org; The Bradshaw Foundation bradshawfoundation.com ; Turkana Basin Institute turkanabasin.org; Koobi Fora Research Project kfrp.com; Maropeng Cradle of Humankind, South Africa maropeng.co.za ; Blombus Cave Project web.archive.org/web; Journals: Journal of Human Evolution journals.elsevier.com/; American Journal of Physical Anthropology onlinelibrary.wiley.com; Evolutionary Anthropology onlinelibrary.wiley.com; Comptes Rendus Palevol journals.elsevier.com/ ; PaleoAnthropology paleoanthro.org.
Cut Marks on 3.4-Million-Year-Old Bone: Earliest Evidence of Tools?
In 2009, 3.4-million-year-old bones — found in Dikika, Ethiopia, near site where a Lucy-like hominin was discovered — with slashes, parallel marks and other cut marks that appear to have been made with stone tools, was presented as evidence that stone tools were produced more than 800,000 years than earlier thought and they could have been made by a possible human ancestor such as Lucy (Australopithecus afarenis).
The marks were made on a rib from a cow-like hoofed creature and a thigh bone from a goat-size animal, possibly from an impala, gazelle or antelope. It was argued that someone used stones to trim flesh from bone and perhaps crush bones to get at the marrow inside. It was also argued that this was the earliest evidence of meat and marrow consumption by hominins. No tools were found at that site, so it was unclear whether the marks were made with handmade tools or just naturally sharp rocks. [Source: Charles Q. Choi, Live Science, May 20, 2015]
"We were just walking along when we discovered the two bones," Shannon McPherron, an archaeologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, told The Guardian. "We picked up the rib fragment, flipped it over and there were these two, clear marks. Soon after, we found the second bone, also with a lot of marks on it. Right away we knew we had something potentially important." [Source: Ian Sample, The Guardian, August 11, 2010 ]
Jennifer Viegas wrote in Discovery News: “Various types of electron microscopy, along with chemical analysis, determined that cut marks were inflicted while one or more individuals carved meat off the bones with a sharp stone tool. Percussion marks were also created when a stone tool broke open the bones to extract their nutritious marrow. The fossilized bones were found sandwiched between volcanic deposits, which permitted reliable dating of them. Before this discovery, the world’s oldest human evidence for butchery dated to 2.5 million years ago and came from Bouri and Gona, Ethiopia. No human remains were found in association with those fossilized prey bones, but A. afarensis remains were previously unearthed near the recent Afar Region discoveries. [Source: Jennifer Viegas Discovery News, August 11, 2010]
Tia Ghose wrote in Live Science: “The bones were found several years ago in the history-rich sediments of Dikika, an area in the Awash River valley in Ethiopia,” an arid region that “has yielded some of the best examples of both early hominin fossils and fossils from anatomically modern early humans. Though archaeologists have not found hominin fossils at this particular site, just a few hundred meters away, other research teams previously found the nearly intact skeleton of a 3.3-million-year-old baby girl Australopithecus, dubbed "the Dikika baby" or "Lucy's baby." (The Dikika baby is not truly Lucy's baby, since she lived 100,000 years before Lucy.) [Source: Tia Ghose, Live Science, August 20, 2015]
“At this particular spot, other paleoanthropologists sifting through 3.4-million-year-old sediments found two bones — one from an antelope-size creature and another from a buffalo-size animal — that had a total of 12 distinctive marks. In a 2010 study published in the journal Nature, researchers proposed that someone used a cutting tool to make those marks. But the news was considered shocking: In 2010, the earliest known stone tools, from Gona, Ethiopia, dated to 2.6 million years ago. In 2011, another research group weighed in, writing in a paper in the journal Proceedings of the National Academy of Sciences that the marks on the bones were likely not cut marks, but instead the marks of sediments rubbing over the bones as wild beasts trampled them over the millennia.”
Marks on 3.4-Million-Year-Old Bones Not Made by Trampling
Some scientists argued the “cut marks”, said to have been made the earliest-known stone tools, could have been made by trampling on the bones but research published in 2015 suggests that is not what happened.Tia Ghose wrote in Live Science: “The new results debunk one theory for how the bones got their marks, and support — but do not, on their own, definitively prove — the alternative hypothesis that ancient human ancestors cut the bones.[Source: Tia Ghose, Live Science, August 20, 2015 |]
“At the time the bones were deposited, the region was a patchwork of swampy forest areas dotted with lakes, and a more open savanna where bigger animals roamed, said lead study author Jessica Thompson, an assistant professor of anthropology at Emory University in Georgia. The tree-swinging Australopithecus likely lived in the forested regions, Thompson said. To help settle the question of whether the animals were trampled, Thompson and her colleagues used a more statistical approach than had been used in the past. Instead of analyzing just the cut marks, the team looked at all the marks in the bone samples found in the region. |
“They tossed a marker — in this case, a hammer — randomly into the bone bed, and then drew a circle around it. They collected all the bones within the circle and studied and catalogued their surfaces under a microscope, repeating the sampling process at various locations in the bone bed. In a separate test, they analyzed all the marks generated on a set of bones that had been experimentally trampled — for a study by other researchers. Then, they compared the bones in both groups with the two bones that appeared to have cut marks. The two bones looked significantly different from both types of samples, suggesting that whatever process left those marks, it wasn't trampling or natural processes in the area, the researchers reported Aug. 13 in the Journal of Human Evolution. |
3.3-Million- Year-Old Stone Tools Found in Northern Kenya
In May 2015, researchers announced the discovery of 3.3-million-year-old stone tools found at a site in Kenya, making the idea that tool-making predated all Homo species more acceptable. If it turns tools are indeed tools, the species that made them is unknown although some scientists have speculated it was Australopithecus afarensis (Lucy). Scientists detailed their findings in the May 21, 2015 issue of Nature.Charles Q. Choi of Live Science wrote: “The 3.3-million-year-old stone artifacts are the first direct evidence that early human ancestors may have possessed the mental abilities needed to figure out how to make razor-sharp stone tools. The discovery also rewrites the book on the kind of environmental and evolutionary pressures that drove the emergence of toolmaking. [Source: Charles Q. Choi, Live Science, May 20, 2015]
Until now, the earliest known tools were about 2.8 million years old, the researchers said. The artifacts are by far the oldest handmade stone tools yet discovered — the previous record-holders, known as Oldowan stone tools, were about 2.6 million years old. "We were not surprised to find stone tools older than 2.6 million years, because paleoanthropologists have been saying for the last decade that they should be out there somewhere," Harmand said. "But we were surprised that the tools we found are so much older than the Oldowan, at 3.3 million years old."
“It remains unknown what species made these stone tools. They could have been created by an as-yet-unknown extinct human species, or by Australopithecus, which is currently the leading contender for the ancestor of the human lineage, or by Kenyanthropus, a 3.3-million-year-old skull of which was discovered in 1999 about a half-mile (1 kilometer) from the newfound tools. It remains uncertain exactly how Kenyanthropus relates to either Homo or Australopithecus. "Sometimes the best discoveries are the ones that raise more questions than provide answers," study co-author Jason Lewis, a paleoanthropologist at Stony Brook University and Rutgers University in New Jersey, told Live Science. "In any of these cases the story is equally new and interesting. We are comfortable not having all of the answers now."
“The stone tools were discovered in the desert badlands of northwestern Kenya, where the arid, rocky terrain resembles a New Mexican landscape. The artifacts were found next to Lake Turkana in 2011 almost by accident. "We were driving in the dry riverbed and took the left branch instead of the right, and got off course," Harmand said. "Essentially, we got lost and ended up in a new area that looked promising. Something was really unique about this place, we could tell that this zone had a lot of hidden areas just waiting to be explored." By the end of the 2012 field season, excavations at the site, named Lomekwi 3, had uncovered 149 "Lomekwian" stone artifacts linked with toolmaking. "It is really exciting and very moving to be the first person to pick up a stone artifact since its original maker put it down millions of years ago," Harmand said.
Traditional View of Tools
Before 2010, the oldest evidence of toolmaking by hominins dated to 2.6 million years ago and includes simple pebble-choppers for hacking and crushing. These Oldowan tools, named after the Olduvai gorge in Tanzania, were wielded by our predecessors for around a million years. The oldest evidence of stone-tool use was a group of more than 2,600 stone flakes estimated to be 2.5 million years old that was discovered in Bouri and Gona in Ethiopia in 1997. These tools had been shaped to make sharp cutting edges. [Source: Ian Sample, The Guardian, August 11, 2010]
Charles Q. Choi of Live Science wrote: “Ancient stone artifacts from East Africa were first uncovered at Olduvai Gorge in Tanzania in the mid-20th century. Those stone tools were later associated with fossils of the ancient human species Homo habilis, discovered in the 1960s. "The traditional view for decades was that the earliest stone tools were made by the first members of Homo," study lead author Sonia Harmand, an archaeologist at Stony Brook University in New York, told Live Science. "The idea was that our lineage alone took the cognitive leap of hitting stones together to strike off sharp flakes and that this was the foundation of our evolutionary success." [Source: Charles Q. Choi, Live Science, May 20, 2015]
Early Hominin Tools: from Australopithecus garhi?
One of the oldest known hominid tools is a 2.6 million-year-old flaked scraping tool found in the Gona region of Ethiopia by a team lead by Sileshi Semaw, an Ethiopian archaeologist now at Indiana University. It is not known who used the tools. Scientists believed it was Australopithecus garhi.
The tools were probably used to break open bones and scrape out the marrow and perhaps to cut meat off the bones. Before this no tools had been linked with australopithecines before. Leg bone of other animals found near the tools had cut and chip marks and signs of hammering.
In 2003, Semaw's team found 2.6 million-year-old tools among bone fragments in the Gona area. Believed to have been used to cut up meat, the tools, scientists say, shed some light on which came first tools or better diets. Semaw told the New York Times, “I believe the stone tools came first and the larger brain came later with a more substantial meat diet."
An antelope jaw with cut marks, indicating its tongue was sliced out with a sharp stone flake was found on the Bouri Peninsuala in Lake Yardi in Ethiopia. The bones, dated to 2.5 million years ago, suggest the toolmakers used tools to scavenge meat and marrow from large animals. Curiously though no actual tools were found at the site. The discovery nearby of Australopithecus garhi bones indicate it again was the most likely the tool maker.
Implications of 3.4-Million-Year-Old Tools
Charles Q. Choi of Live Science wrote: “Chimpanzees and monkeys are known to use stones as tools, picking up rocks to hammer open nuts and solve other problems. However, until now, only members of the human lineage — the genus Homo, which includes the modern human species Homo sapiens and extinct humans such as Homo erectus — were thought capable of making stone tools.[Source: Charles Q. Choi, Live Science, May 20, 2015]
If early hominins were using tools so early, that means their cognitive abilities were also more advanced than previously thought, Briana Pobiner, a paleoanthropologist at the Smithsonian Institution, told Live Science. For instance, humans' closest living relatives, chimpanzees, may crack nuts using stones or may sharpen sticks to hunt other primates called bush babies, but they do that with their teeth. Making stone tools involves bashing one stone on another rock to make the desired pointy shape. "To make a stone tool, you use a tool to make a second tool," Pobiner told Live Science.[Source: Tia Ghose, Live Science, August 20, 2015 |]
That's a different cognitive process, she said. "There's a lot of planning and forethought involved," Pobiner said, from picking the right kind of rock, to striking with the tool in just the right way to get the stone flaked off. Either way, the new study, combined with the discovery of similarly aged tools in Kenya, make the notion that ancient human ancestors cut the Dikika bones much more likely, Pobiner said. |
3.4-Million-Year-Old Tools and Australopithecus Afarensis (Lucy)
Ian Sample wrote in The Guardian: “The butchered bones were discovered close to where the skeleton of a probable human ancestor, nicknamed Lucy, was found. Lucy belonged to a species called Australopithecus afarensis and lived in the region around 3.2 million years ago. At the time, the region was warm and wet, with patches of grassland and heavily forested areas populated with early forms of giraffes, monkeys, elephants and rhinos. “"Now, when we imagine Lucy walking around the east African landscape looking for food, we can for the first time imagine her with a stone tool in hand looking for meat," said McPherron. The skeleton of another female, "Selam", was found 200 miles away. [Source: Ian Sample, The Guardian, August 11, 2010 |=|]
“The use of simple stone tools to remove meat and marrow marks a crucial moment in the human story. As the ancestors of early humans turned to meat for sustenance, they were able to grow larger brains which in turn enabled them to make more sophisticated tools. "These bones may take us to the very beginning of that process," said Chris Stringer, head of human origins at the Natural History Museum in London. "What we need from these sites now are evidence of the stone tools themselves, so we can see if they were manufactured or were natural stones that happened to be used for butchery," he added. |=|
“Lucy and others of her species probably carried natural stone tools around with them to use when they encountered a dead animal. "It's not a trivial thing to leave the trees behind, wander out onto this open landscape and start removing flesh and marrow from a carcass. Those same carcasses were attracting carnivores that look at these early hominins as a meal, so they were taking a major risk," said McPherron.” |=|
Jennifer Viegas wrote in Discovery News: “Since the Afar stone tools were transported to the kill or scavenge site from nearly four miles away, A. afarensis must have valued the sharp objects. What’s unclear, however, is whether or not the ancient hominins made the stones themselves, or just picked already sharp stones up from the ground.” [Source: Jennifer Viegas Discovery News, August 11, 2010]
Revised Theory of Toolmaking
Charles Q. Choi of Live Science wrote: “Conventional thinking has been that sophisticated toolmaking came in response to a change in climate that led to shrinking forests and the spread of savannah grasslands. Stone blades likely helped ancient humans get food by helping them cut meat off the carcasses of animals, given how there was then less food such as fruit to be found in the forest. However, these findings suggest that Lomekwian stone tools may have been used for breaking open nuts or tubers, bashing open dead logs to get at insects inside, or maybe something not yet thought of. "The Lomekwi 3 evidence suggests that important evolutionary changes that would later be really important for Homo to survive on the savannah were actually evolving beforehand, in a still-wooded environment," Lewis said.[Source: Charles Q. Choi, Live Science, May 20, 2015 ]
This discovery also has implications for understanding the evolution of the human brain, researchers said. Toolmaking required a level of dexterity and grip that suggests that changes in the brain and spinal tract needed for such activity could have evolved before 3.3 million years ago. "The capabilities of our ancestors and the environmental forces leading to early stone technology are a great scientific mystery," Richard Potts, director of the Human Origins Program at the Smithsonian's National Museum of Natural History, who was not involved in the research, said in a statement. The newly dated tools "begin to lift the veil on that mystery, at an earlier time than expected."
“The scientists are now looking at the surfaces and edges of the tools under microscopes and with laser scans to try to reconstruct how they were used, "and also studying the sediment in which they were found to search for trace elements or residues of any possible plant or animal tissues that could be left on them after use," Harmand said. The site is still under excavation, and Harmand said other artifacts could exist from early attempts at knapping. "We think there are older, even more rudimentary, stone tools out there to be found, and we will be looking for them over the coming field seasons," he added.”
Reevaluation of the Study of Hominin Tool Use
In 2012, archaeologydaily.com said: “The earliest evidence of human tool use may be written on the bones of other animals, but in order to produce reliable conclusions, researchers are calling for improved tools and analysis, including an easy to access large collection of sample specimens and more unified standards. Archaeologists and anthropologists look beyond the fossils of ancient human relatives to interpret the presence of our ancestors, including the items associated with day-to-day life, from discarded tools to the ashes from fire pits. The marks made by crude stone cutting tools on the bones of animals that early humans ate are another piece of evidence. [Source: archaeologydaily.com,April 13, 2012 \^]
These markings have tremendous impact on the understanding of human evolution. “Most of our interpretations of what early humans were doing depend on correctly identifying what they were doing on bones,” said Manuel Dominguez-Rodrigo, an anthropologist and archaeologist at the Complutense University of Madrid, in Spain. “Detecting exactly how these marks were made on the bones is what makes us grant support to one model of human evolution or a different model of human evolution.”These types of bone marks are difficult to interpret. Cutting tools leave marks on bones, but so can other factors, including other predators’ teeth and weathering. This has led to notable disagreements about individual bone markings. \^\
“For decades, researchers have scoured sites in Africa for both marked bones and ancient tools. They have also been experimenting on and collecting the bones of prey animals in order to better understand the effects of many factors, from the biting and tearing of a feeding crocodile to chemical processes. “Butchery marks are as important as stone tools,” said Jackson Njau, a paleoanthropologist at Indiana University in Bloomington and an associate researcher at the Stone Age Institute. “But stone tools are rocks; they don’t decay.” \^\
“Writing in an April 2012 issue of Science, Njau calls for measures to help scientists make consistent, reliable determinations of the causes of marks. Njau said that one aspect of the solution would be gathering together a large online collection of samples for making comparisons. He has made extensive efforts to document the marks left by crocodile teeth, which can create patterns similar to those made by stone tools. Because marks that look superficially similar reveal crucial differences under a microscope, researchers must compare a new mark to numerous others before making a firm determination of its origin. “If large collections now held by different researchers and museums were available in an online database of microscopic images, researchers could instantly access images of bones modified by many processes, such as the chewing action of different carnivores or cuts and slices made by researchers recreating butchery techniques with ancient-style tools. “That would certainly be helpful,” said Pat Shipman, a now-retired anthropologist who in 1981, published one of the first papers on microscopic analysis of bone markings. “How big your comparative sample is and how varied it is and how varied the conditions to which the bone was subjected all influences your ability to make a diagnosis of that mark.” \^\
“Dominguez-Rodrigo said that Njau’s ideas could help, but would not completely solve the issues. He emphasized that looking at published photographs cannot convey the same knowledge as looking through a microscope at many bones deformed in a wide variety of ways. “Nothing replaces doing the experimentation,” said Dominguez-Rodrigo. “The subtleties are hard to capture and describe,” said Shipman. “You do have to get that gut-level intuitive feel for it.”
“Njau said that comparisons are important, but also the criteria used by researchers. He emphasized the need for considering the contextual information of a bone marking in its interpretation so that additional indications of the history surrounding the fossil can be considered. He said that scientists must weigh additional factors when analyzing bones for evidence of tool use, including the presence in the same soil layer of stone artifacts, carnivore activity and other factors. “We have these resources, it’s time now to put this together to make it available,” said Njau.” \^\
Image Sources: Wikimedia Commons, except 3.3 million-year-old Kenya tools, BBC, and Dikika tools, Wired
Text Sources: National Geographic, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Nature, Scientific American. Live Science, Discover magazine, Discovery News, Times of London, Natural History magazine, Archaeology magazine, The New Yorker, Time, Newsweek, BBC, The Guardian, Reuters, AP, AFP and various books and other publications.
Last updated September 2018