Oldowan

• 1. Introduction

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  At Nyayanga, a site on Kenya's Homa Peninsula, archaeologists in 2015 uncovered the oldest known tools of the Oldowan tradition. The flakes are dated to roughly 2.9 million years ago. They lay near Paranthropus teeth and two butchered hippo skeletons. The Oldowan is the earliest widespread stone-working technology recognized in the archaeological record. The tools themselves are unglamorous, a chip struck off one rock using another, nothing more. Nobody knows for certain which hominin species swung that first hammerstone. What follows traces how researchers have argued over what to call this technology and how it was struck and shaped. It also asks who was capable of making these tools, and how something this simple traveled across Africa and beyond. Eventually a more refined tradition took its place.

• 2. Naming And Classification

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  The archaeologist Louis Leakey found the first tools of this kind at Olduvai Gorge in Tanzania during the 1930s. That discovery is why the industry carries the name Oldowan today. Some contemporary archaeologists and palaeoanthropologists prefer a different label, Mode 1, reserved for pebble tool industries like this one. Mode 2 designates bifacially worked tools, including Acheulean handaxes, while Mode 3 covers tools made from prepared cores.

  Mary Leakey was the first to build a classification system for Oldowan assemblages. She organized the tools by their presumed use into choppers, scrapers, and pounders. More recent classifications focus on manufacture instead, since assuming a tool's use from its shape alone is problematic. Isaac and colleagues proposed four categories in response. Flaked Pieces covered cores and choppers, and Detached Pieces covered flakes and fragments. Pounded Pieces meant cobbles used as hammerstones, and Unmodified Pieces meant manuports, stones carried to a site without being altered. Because the blanks chosen for these tools already resembled the finished product in pebble form, Oldowan tools are sometimes called pebble tools.

  For decades a different name, Abbevillian, described similar tools found in Europe. That label prevailed until the Leakey family's older, comparable finds at Olduvai Gorge promoted the idea of an African origin for humanity. Oldowan soon replaced Abbevillian for describing African and Asian lithics, though the older term survives, now restricted mostly to Europe. By the late 20th century, discrepancies in dating had made it hard to separate Abbevillian from Acheulean, since both traditions included flakes and bifaces. Researchers eventually settled on complexity as the dividing line: simply struck tools count as Oldowan, while retouched or reworked tools count as Acheulean. Retouching describes reworking a finished tool a second time, chipping tiny flakes away to sharpen and straighten its edge, typically through pressure flaking.

• 3. Crafting The Tools

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  Quartz, quartzite, basalt and obsidian supplied most of the raw material for these tools, with flint and chert coming into use later. Any rock capable of holding an edge would work, and river cobbles were the main source, supplying both hammerstones and striking platforms. The earliest tools were little more than split cobbles, and it is not always obvious which piece counts as the flake. Later toolmakers clearly identified and reworked flakes instead, a shift researchers can trace across the assemblages. Complaints that these artifacts could not be told apart from naturally fractured stone pushed archaeologists toward careful, systematic study of Oldowan technique. Knappers have since duplicated these methods many times over, making misidentification of a find far less likely today.

  Making a tool started by swinging a rounded hammerstone into the striking platform, the edge of a chosen core rock, to knock off a flake with a sharp conchoidal fracture. That process is what researchers call lithic reduction. The chip knocked loose in the strike is the flake, and some flakes served as tools in their own right. Below the point of impact, the core carries a distinctive bulb marked by fine fissures. The detached flake itself shows ripple marks across its fracture surface.

  At Swartkrans, a bone shaft with a polished point turned up in a layer called Member I, dated to 1.8-1.5 million years ago. Some researchers have proposed a broader tradition behind this find, called the Osteodontokeratic, or bone-tooth-horn, industry. Raymond Dart hypothesized the idea, though it remains less certain. That basic choice, between a flake and a cobble, shaped everything a hominin could do with the tool next.

• 4. Shapes And Everyday Uses

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  Mary Leakey sorted these tools into four groups: Heavy Duty, Light Duty, Utilized Pieces, and Debitage, meaning waste. Heavy-duty tools were mainly cores. A chopper carries an edge on one side, unifacial if that edge was flaked on a single face and bifacial if flaked on two. Discoid tools are roughly circular with an edge running around the whole piece, while polyhedral tools carry edges shaped like a polyhedron. Spheroidal hammer stones round out the heavy-duty category.

  Light-duty tools were mainly flakes: scrapers, awls with points for boring, and burins with points for engraving. Some of these functions crossed over into heavy-duty tools too, since heavy-duty scrapers existed alongside their lighter counterparts. Utilized pieces began life with one purpose in mind but were pressed into other uses as circumstances demanded. Researchers have proposed that this opportunistic reworking, driven by labor needs or even signaling, explains why similar tools ended up in such different shapes.

  Observations of modern apes and hunter-gatherers have guided theories about what these tools actually did. Nuts and bones were cracked by hammering them against a stone anvil, a use attested by battered and pitted stones found at Oldowan sites. Heavy-duty tools likely served as axes for woodworking; once a branch was separated, it could be scraped clean or hollowed with a pointed tool. Microscopic wear on tool edges matches the marks left by scraping wood. Hide preparation required cutting, piercing and scraping away residue, tasks for which flakes were best suited.

  Lawrence Keeley, building on the earlier work of Sergei Semenov, examined tool edges under a high-powered optical microscope. He manufactured tools from scratch, used them for these proposed purposes, and found the resulting wear marks matched those on genuine prehistoric artifacts. Electron-microscope studies of cut marks on ancient bones have produced the same result. None of this wear analysis, though, settles the question of exactly which hominin's hand held the tool.

• 5. Who Made The Tools

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  A fringe argument holds that only the genus Homo was capable of making these tools, a position tied to religious bias and intelligent-design thinking rather than evidence. Fossil evidence instead shows early features of the precision grip in Australopithecines, the hand control needed to strike a flake accurately. Current thinking credits Oldowan tools to both late Australopithecus and early Homo.

  Homo habilis earned its name, meaning skillful, because researchers once considered it the first tool-using human ancestor. The genus Homo itself was originally defined to separate tool-using species from their tool-less predecessors. That same logic shaped the name Australopithecus garhi, garhi meaning surprise. It was discovered in 1996 and described as the missing link between Australopithecus and Homo. Evidence also points to some species of Paranthropus using stone tools.

  Modern wild chimpanzees in West Africa complicate any tidy story about tool-making being uniquely human. Researchers studying their nut-cracking found a clear operational sequence, and sometimes the chimpanzees created unintentional flakes in the process. Chimpanzee hammers differ in shape from Oldowan hammers, but their stone use suggests more than one hominin species could have made these tools. Hand morphology preserved in the fossil record, together with experimental replication, points to physical traits suited for precise stone-knapping. Most Oldowan toolmakers were right-handed, evidence that handedness, or lateralization, had already evolved by this period. It remains unclear how closely that lateralization resembles the modern kind, since other animals show handedness as well. Handedness says something about an individual, but nothing about how these hominins organized themselves in groups to find food.

• 6. Foraging And Social Life

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  In the mid-1970s, Glynn Isaac proposed that early hominins had a home base, foraging outward and returning with high-quality food to share and process. His model, called Central Place Foraging, touched off a debate that has run for decades. Critics accused Isaac of projecting too much modern behavior onto early hominins, imagining relatively free-form searches radiating outward from a fixed point.

  A second group of theories took modern chimpanzee behavior as its starting point instead. In this view, hominins followed relatively fixed foraging routes, leaving tools along a constant track rather than at a home base. A third group of theories pictured loose bands scouring their range, moving carcasses away from dangerous kill sites and leaving tools more or less at random. Each model implies a different social strategy, ranging from the relative altruism of a shared base camp to the disjointed pattern of scattered, individual searches.

  The large number of bones found at many sites is too great to be the work of one individual. Scatter patterns at these sites likewise imply the presence of many different people over time. Modern African primates have fluid group boundaries, with individuals joining bands and later leaving them. The tools at a single site probably reflect many overlapping, even competing, groups working the same territory over time. Given the huge span of time and the number of hominin species involved, more precision than that is difficult to achieve.

  Early models of these hominins treated them mainly as hunters. The animals they butchered included waterbuck, hartebeest, springbok, pig and zebra. That they were omnivores is not in question, given their use of digging implements and hammer stones for cracking nuts. Lewis Binford noticed that bones at Olduvai contained a disproportionately high share of extremities, parts low in food value. He concluded that other predators had already taken the best meat, leaving hominins to scavenge what remained. A counter view holds that bringing down large animals alone would be difficult, but a group could manage it through pack hunting. It is also possible hominins hunted smaller animals while still driving carnivores off larger kills, risking being driven off in turn. Whatever mix of hunting and scavenging sustained them, this same toolkit eventually traveled with these hominins far beyond the East African sites where Binford counted his bones.

• 7. A Technology Across Continents

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  Early Oldowan tools are known from Gona in Ethiopia, near the Awash River, dated to about 2.6 million years ago. Between 2.4 and 1.7 million years ago, the technology flourished across eastern Africa and spread into southern Africa. At 1.7 million years ago, the first Acheulean tools appear, even as Oldowan assemblages kept being produced alongside them. Finding both traditions in the same places at the same times forced a rethink of the old assumption that Acheulean simply succeeded Oldowan. The overlap may reflect different hominin species sharing a landscape, or a single species switching techniques to suit different circumstances.

  Before 1.8 million years ago, Homo erectus had already spread outside Africa, reaching Java by that same date and northern China by 1.66 million years ago. No Acheulean assemblages have turned up in these newly settled regions. In China, only Mode 1, Oldowan-style assemblages were produced, while stone tools of this age remain unknown in Indonesia.

  By 1.8 million years ago, early Homo had also reached Europe, evidenced by fossil remains and Oldowan tools at Dmanisi in Georgia. Further traces of their activity have been excavated in Spain, at sites in the Guadix-Baza basin and near Atapuerca. Most early European sites yield Mode 1, or Oldowan, assemblages rather than Acheulean ones. The earliest Acheulean sites in Europe date to only around 0.5 million years ago, and the tradition never spread into eastern Asia at all. When Oldowan production finally ended is unclear from the record, though other tool-making traditions appear to have replaced it by about 0.25 million years ago.

  In 2015, researchers announced an even older find: stone tools at the Lomekwi site in Kenya, dated to as early as 3.3 million years ago. That age predates current estimates for the origin of the genus Homo by roughly half a million years. It places the toolmakers among the direct australopithecine ancestors of Homo, in the pre-human period. Whether this so-called Lomekwian industry has any real relationship to the Oldowan tools that followed it remains an open question.