Stone tools have been used throughout human history but are most closely associated with prehistoric cultures and in particular those of the Stone Age. Stone tools may be made of either ground stone or knapped stone, the latter fashioned by a craftsman called a flintknapper. Stone has been used to make a wide variety of tools throughout history, including arrowheads, spearheads, hand axes, and querns. Knapped stone tools are nearly ubiquitous in pre-metal-using societies because they are easily manufactured, the tool stone raw material is usually plentiful, and they are easy to transport and sharpen.
The study of stone tools is a cornerstone of prehistoric archaeology because they are essentially indestructible and therefore a ubiquitous component of the archaeological record. Ethnoarchaeology is used to further the understanding and cultural implications of stone tool use and manufacture.
Knapped stone tools are made from cryptocrystalline materials such as chert, flint, radiolarite, chalcedony, obsidian, basalt, and quartzite via a splitting process known as lithic reduction. One simple form of reduction is to strike stone flakes from a nucleus (core) of material using a hammerstone or similar hard hammer fabricator. If the goal is to produce flakes, the remnant lithic core may be discarded once too little remains. In some strategies, however, a flintknapper makes a tool from the core by reducing it to a rough unifacial or bifacial preform, which is further reduced by using soft hammer flaking or by pressure flaking the edges. More complex forms of reduction may produce highly standardized blades, which can then be fashioned into a variety of tools such as scrapers, knives, sickles, and microliths.
Evolution.
Archaeologists classify stone tools into industries (also known as complexes or technocomplexes) that share distinctive technological or morphological characteristics.
In 1969 in the 2nd edition of "World Prehistory", Grahame Clark proposed an evolutionary progression of flint-knapping in which the "dominant lithic technologies" occurred in a fixed sequence from Mode 1 through Mode 5. He assigned to them relative dates: Modes 1 and 2 to the Lower Palaeolithic, 3 to the Middle Palaeolithic, 4 to the Upper Paleolithic, and 5 to the Mesolithic, though there were other lithic technologies outside these Modes. Each region had its own timeline for the succession of the Modes: for example, Mode 1 was in use in Europe long after it had been replaced by Mode 2 in Africa.
Clark's scheme was adopted enthusiastically by the archaeological community. One of its advantages was the simplicity of terminology; for example, the Mode 1 / Mode 2 Transition. The transitions are currently of greatest interest. Consequently, in the literature the stone tools used in the period of the Palaeolithic are divided into four "modes", each of which designates a different form of complexity, and which in most cases followed a rough chronological order.
Pre-Mode I.
Stone tools found from 2011 to 2014 at the Lomekwi archeology site near Lake Turkana in Kenya, are dated to be 3.3 million years old, and predate the genus "Homo" by about one million years. The oldest known "Homo" fossil is about 2.4–2.3 million years old compared to the 3.3 million year old stone tools. The stone tools may have been made by "Australopithecus afarensis", the species whose best fossil example is Lucy, which inhabited East Africa at the same time as the date of the oldest stone tools, a yet unidentified species, or by "Kenyanthropus platyops" (a 3.2 to 3.5-million-year-old Pliocene hominin fossil discovered in 1999). Dating of the tools was done by dating volcanic ash layers in which the tools were found and dating the magnetic signature (pointing north or south due to reversal of the magnetic poles) of the rock at the site.
Grooved, cut and fractured animal bone fossils, made by using stone tools, were found in Dikika, Ethiopia near (200 yards) the remains of Selam, a young "Australopithecus afarensis" girl who lived about 3.3 million years ago.
Mode I: The Oldowan Industry.
The earliest stone tools in the era of genus "Homo" are Mode 1 tools, and come from what has been termed the Oldowan Industry, named after the type of site (many sites, actually) found in Olduvai Gorge, Tanzania, where they were discovered in large quantities. Oldowan tools were characterised by their simple construction, predominantly using core forms. These cores were river pebbles, or rocks similar to them, that had been struck by a spherical hammerstone to cause conchoidal fractures removing flakes from one surface, creating an edge and often a sharp tip. The blunt end is the proximal surface; the sharp, the distal. Oldowan is a percussion technology. Grasping the proximal surface, the hominid brought the distal surface down hard on an object he wished to detach or shatter, such as a bone or tuber. Experiments with modern humans found that all four Oldowan knapping techniques can be invented by knapping-naive participants, and that the resulting Oldowan tools were used by the experiment participants to access a money-baited box.
The earliest known Oldowan tools yet found date from 2.6 million years ago, during the Lower Palaeolithic period, and have been uncovered at Gona in Ethiopia. After this date, the Oldowan Industry subsequently spread throughout much of Africa, although archaeologists are currently unsure which Hominan species first developed them, with some speculating that it was "Australopithecus garhi", and others believing that it was in fact "Homo habilis". "Homo habilis" was the hominin who used the tools for most of the Oldowan in Africa, but at about 1.9-1.8 million years ago "Homo erectus" inherited them. The Industry flourished in southern and eastern Africa between 2.6 and 1.7 million years ago, but was also spread out of Africa and into Eurasia by travelling bands of "H. erectus", who took it as far east as Java by 1.8 million years ago and Northern China by 1.6 million years ago.
Mode II: The Acheulean Industry.
Eventually, more complex Mode 2 tools began to be developed through the Acheulean Industry, named after the site of Saint-Acheul in France. The Acheulean was characterised not by the core, but by the biface, the most notable form of which was the hand axe. The Acheulean first appears in the archaeological record as early as 1.7 million years ago in the West Turkana area of Kenya and contemporaneously in southern Africa.
The Leakeys, excavators at Olduvai, defined a "Developed Oldowan" Period in which they believed they saw evidence of an overlap in Oldowan and Acheulean. In their species-specific view of the two industries, Oldowan equated to "H. habilis" and Acheulean to "H. erectus". Developed Oldowan was assigned to "habilis" and Acheulean to "erectus". Subsequent dates on "H. erectus" pushed the fossils back to well before Acheulean tools; that is, "H. erectus" must have initially used Mode 1. There was no reason to think, therefore, that Developed Oldowan had to be "habilis"; it could have been "erectus". Opponents of the view divide Developed Oldowan between Oldowan and Acheulean. There is no question, however, that "habilis" and "erectus" coexisted, as "habilis" fossils are found as late as 1.4 million years ago. Meanwhile, African "H. erectus" developed Mode 2. In any case a wave of Mode 2 then spread across Eurasia, resulting in use of both there. "H. erectus" may not have been the only hominin to leave Africa; European fossils are sometimes associated with "Homo ergaster", a contemporary of "H. erectus" in Africa.
In contrast to an Oldowan tool, which is the result of a fortuitous and probably unplanned operation to obtain one sharp edge on a stone, an Acheulean tool is a planned result of a manufacturing process. The manufacturer begins with a blank, either a larger stone or a slab knocked off a larger rock. From this blank he or she removes large flakes, to be used as cores. Standing a core on edge on an anvil stone, he or she hits the exposed edge with centripetal blows of a hard hammer to roughly shape the implement. Then the piece must be worked over again, or retouched, with a soft hammer of wood or bone to produce a tool finely knapped all over consisting of two convex surfaces intersecting in a sharp edge. Such a tool is used for slicing; concussion would destroy the edge and cut the hand.
Some Mode 2 tools are disk-shaped, others ovoid, others leaf-shaped and pointed, and others elongated and pointed at the distal end, with a blunt surface at the proximal end, obviously used for drilling. Mode 2 tools are used for butchering; not being composite (having no haft) they are not very effective killing instruments. The killing must have been done some other way. Mode 2 tools are larger than Oldowan. The blank was ported to serve as an ongoing source of flakes until it was finally retouched as a finished tool itself. Edges were often sharpened by further retouching.
Mode III: The Mousterian Industry.
Eventually, the Acheulean in Europe was replaced by a lithic technology known as the Mousterian Industry, which was named after the site of Le Moustier in France, where examples were first uncovered in the 1860s. Evolving from the Acheulean, it adopted the Levallois technique to produce smaller and sharper knife-like tools as well as scrapers. Also known as the "prepared core technique", flakes are struck from worked cores and then subsequently retouched. The Mousterian Industry was developed and used primarily by the Neanderthals, a native European and Middle Eastern hominin species, but a broadly similar industry is contemporaneously widespread in Africa.
Mode IV: The Aurignacian Industry.
The widespread use of long blades (rather than flakes) of the Upper Palaeolithic Mode 4 industries appeared during the Upper Palaeolithic between 50,000 and 10,000 years ago, although blades were produced in small quantities much earlier by Neanderthals. The Aurignacian culture seems to have been the first to rely largely on blades. The use of blades exponentially increases the efficiency of core usage compared to the Levallois flake technique, which had a similar advantage over Acheulean technology which was worked from cores.
Expansion to the New World.
As humans spread to the Americas in the Late Pleistocene, Paleo-Indians brought with them related stone tools, which evolved separately from Old World technologies. The Clovis point is the most widespread example of Late Pleistocene points in the Americas, dating to about 13,000 years ago.
Mode V: The Microlithic Industries.
Mode 5 stone tools involve the production of microliths, which were used in composite tools, mainly fastened to a shaft. Examples include the Magdalenian culture. Such a technology makes much more efficient use of available materials like flint, although required greater skill in manufacturing the small flakes. Mounting sharp flint edges in a wood or bone handle is the key innovation in microliths, essentially because the handle gives the user protection against the flint and also improves leverage of the device.
Neolithic industries.
In prehistoric Japan, ground stone tools appear during the Japanese Paleolithic period, that lasted from around 40,000 BC to 14,000 BC. Elsewhere, ground stone tools became important during the Neolithic period beginning about 10,000 BC. These ground or polished implements are manufactured from larger-grained materials such as basalt, jade and jadeite, greenstone and some forms of rhyolite which are not suitable for flaking. The greenstone industry was important in the English Lake District, and is known as the Langdale axe industry. Ground stone implements included adzes, celts, and axes, which were manufactured using a labour-intensive, time-consuming method of repeated grinding against an abrasive stone, often using water as a lubricant. Because of their coarse surfaces, some ground stone tools were used for grinding plant foods and were polished not just by intentional shaping, but also by use. Manos are hand stones used in conjunction with metates for grinding corn or grain. Polishing increased the intrinsic mechanical strength of the axe. Polished stone axes were important for the widespread clearance of woods and forest during the Neolithic period, when crop and livestock farming developed on a large scale. They are distributed very widely and were traded over great distances since the best rock types were often very local. They also became venerated objects, and were frequently buried in long barrows or round barrows with their former owners.
During the Neolithic period, large axes were made from flint nodules by knapping a rough shape, a so-called "rough-out". Such products were traded across a wide area. The rough-outs were then polished to give the surface a fine finish to create the axe head. Polishing increased the strength and durability of the product. There