Olduwan

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Olduwan (earlier spelled Oldowan or sometimes Oldawan) is an anthropological designation for an industry of stone tools used by prehistoric hominans of the Lower Paleolithic. The Olduwan is the very first stone tool assemblage in prehistory.

Sometimes they are called "core tools", "pebble tools", "bifaces" or "choppers." These terms have generally been abandoned because they are not accurate or apply to more than one tradition. Olduwan tools are not necessarily cores, pebbles, or bifaces, and comprise more than hand-axes; moreover, those terms could apply equally to Acheulean tools. "Olduwan" is very specific and is preferable by far.

Olduwan tool use was so ancient that it probably did not begin with Homo sapiens. It spanned such a long period that its users comprised a number of species of hominina, perhaps even more than one genus.

"Olduwan" therefore does not properly refer to a culture, as it must have included many cultures. However, they were all similar or the same and changed very slowly. Some writers do refer to "the Olduwan culture" as a common name. One should also remember that a neo-Olduwan has been created in educational circles of a far different culture than the originals.

Contents 1 Sites and archaeologists 1.1 East Africa 1.1.1 The type site 1.1.2 Omo River basin 1.1.3 Afar Triangle 1.1.4 East Turkana 1.1.5 West Turkana 1.1.6 Olduvai Gorge 1.2 South Africa 1.2.1 Swartkrans 1.2.2 Sterkfontein 1.3 The East 1.3.1 Riwat, Pakistan 1.3.2 Kashafrud, Iran 1.3.3 el'Ubeidiza, Jordan river valley 1.4 Europe 1.4.1 Italy 1.4.2 Former Czechoslovakia 1.4.3 Hungary 1.4.4 Germany 1.4.5 France 2 Dates and ranges 3 The tools 3.1 Manufacture of the tools 3.2 Shapes and uses of the tools 3.3 The Acheulian equivocation 4 The tool users 5 Olduwan Culture 6 Notes 7 Sources 8 External links

[edit] Sites and archaeologists

A complete catalog of Olduwan tool sites would be too extensive for listing here. Hominid populations were probably never very dense, but the span of time is immense. Moreover, the tools continue to be manufactured for purposes of education or fraud.

The tools are found in many geologic contexts of habitable sites: terraces or banks of rivers and lakes or pools, caves, or just lying around in large quantities on open ground. A curious folk aetiology came to be associated with them. They were called "thunderstones", the supposed results of lightning strikes, or "elfshot", missiles that the elves projected at livestock.

Some of the better known sites are as follows.

[edit] East Africa

[edit] The type site

The Olduwan industry is named after discoveries made in the Olduvai Gorge of Tanzania in east Africa by the Leakey family: primarily Mary, wife of Louis, but also Louis and their son, Richard. This is not the first location where these tools have been found. They had already been turning up in Europe and Asia for some time, under the names of Chellean and Abbevillian.

The region of the oldest tool sites is unquestionably the East African Rift system, on the sediments of ancient streams and lakes. This location is consistent with what we know of the evolution of man. Genetic studies tell us that the human line diverged from the chimpanzee line, and the native territory of the latter is the forests of Central Africa nearby. Fossil chimpanzees have been found in Kenya.

The forests of central and west Africa are a stable environment containing food in abundance. The chimpanzees must have reached an ecological balance with it. There was no need for them to evolve further. East Africa is a land of often harsh and unstable environments, where food cannot just be plucked off the bough. Any animal living there would require and use sufficient variability to evolve into more successful forms. A facility for tool using would be just the right one to vary.

[edit] Omo River basin

The eldest Olduwan comes from the Shungura formation of the Omo River basin. This formation documents the sediments of the Plio-Pleistocene and provides a record of the hominins that lived there. Olduwan begins in levels E and F at 2.4-2.3 MYA.

The tools are never found in direct association with the hominins, but it is assumed a priori that they would be the strongest candidates for tool manufacture. There are no hominins in those layers, but the same layers elsewhere in the Omo valley contain Paranthropus and early Homo fossils. Paranthropus occurs in the preceding layers. In the last layer at 1.4 MYA is only Homo erectus.

[edit] Afar Triangle

Sites in the Gona river system in the Hadar region of the Afar triangle, excavated by Helene Roche, J. W. Harris and Sileshi Semaw, yielded the oldest known Olduwan assemblages, dating to about 2.6 MYA. Recent excavations have even yielded tools in association with cut-marked bones, showing that from the beginning of the production of Olduwan tools they were used in meat processing/acquiring activities.

[edit] East Turkana

Main article: Koobi Fora

The numerous Koobi Fora sites on the east side of Lake Turkana are now part of Sibiloi National Park. Many scientists of various disciplines have participated in research there, but the initial sites were excavated by Richard Leakey and his wife, Meave, Jack Harris, Glynn Isaac and a few others. Currently the artifacts are classified as Olduwan or KBS Olduwan, dated from 1.9-1.7 MYA, Karari (or advanced Olduwan), dated to 1.6-1.4 MYA, and some early Acheulean at the end of the Karari. Over 200 hominins have been found, including Australopithecus and Homo.

[edit] West Turkana

[edit] Olduvai Gorge

Even though it is the type site, Olduwan from here is not the oldest. It occurs in Beds I-IV. Bed I, dated 1.85 MYA to 1.7 MYA, contains Olduwan and fossils of Paranthropus boisei as well as Homo habilis, as does Bed II, 1.7-1.2 MYA. H. habilis gives way to Homo erectus at about 1.6 MYA but P. boisei goes on. Olduwan continues to Bed IV at 800,000 to 600,000 BP.

[edit] South Africa

[edit] Swartkrans

The Swartkrans site is a cave filled with layered fossil-bearing limestone deposits. Olduwan is found in Members (layers) I-III, 1.8-.5 MYA, in association with Paranthropus robustus and Homo habilis. The Member I assemblage also includes a shaft of pointed bone polished at the pointed end.

Noticing that Member I contained a high percentage of primate remains compared to other animal remains, which is something of a paradox if you are hypothesizing that H. habilis or P. robustus lived in the cave, C. K. Brain conducted a more detailed study and discovered the cave had been the abode of leopards, who preyed on the hominins.^[1]

[edit] Sterkfontein

Another site of limestone caves is Sterkfontein, not far from Swartkrans. Member (layer) 5 there, dating from 2 MYA to 1.5 MYA, contains fossils of Homo habilis as well as Olduwan tools.

[edit] The East

Olduwan tools have been found at sites in south west Asia.

[edit] Riwat, Pakistan

Tools from 2 MY BP.

[edit] Kashafrud, Iran

Tools from Late Pliocene-Early Pleistocene.

[edit] el'Ubeidiza, Jordan river valley

Tools from 2 MY BP.

[edit] Europe

[edit] Italy

[edit] Former Czechoslovakia

Tools in ancient lake deposits at Przeletice and a cave site at Stranska Skala, dated no later than .5 MYA.

[edit] Hungary

Tools at a spring site at Vertesszllos, .5 MYA.

[edit] Germany

Tools in river gravels, Karlich, .5 MYA.

[edit] France

Abbeville, 1-.5 MYA. Vallonet cave, Riviera. Soleihac, open-air site in Massif Centrale.

[edit] Dates and ranges

Clearly identified Olduwan tools should not be regarded as evidence of the first use of tools in any way. Many animals use tools, including many of the primates. Because of this, it would be very hard indeed to establish a date for "first tool use."

Moreover, the manufacture of stone tools implies a stage in which unmodified stones were used. These also would be difficult to identify; nevertheless, a quasi-tradition of "Eoliths" ("dawn stones") exists for stones thought to have been in this category.

The first clearly manufactured Olduwan tools are dated to as early as 2.6 million years ago in East Africa. Layers from that age can only be dated very roughly; consequently, the 2.6 should be regarded as a rough guideline. The start could have been later, or more probably earlier, nor, unless new techniques of dating are found, is a precise date ever likely to be established.

There is a floruit of Olduwan tools in East Africa, spreading to South Africa, between 2.4 and 1.7 MY. At 1.7 MYA the evidence becomes paradoxical to the previous world view of Stone Age archaeology. The first Acheulean appears at about then. Moreover, it continues on in parallel to Olduwan, sometimes in sites near each other. Acheulian had been supposed to follow Abbevillan. African Acheulean precedes European Abbevillian and there is certainly no sequence of replacement.

A number of solutions are possible and have been offered as explanation. Perhaps different hominins used the two traditions, or the same hominins for different purposes, or the same hominins with access to different stone.

The problem has not been resolved, but it shouldn't concern us too greatly. There are parallel circumstances in the transition to metal, when some people in mining regions used almost all metal implements, while their neighbors in poor regions continued on in the stone age. Tool use is not as simple as a progression of replacements.

At about that time, 1.7 MYA, Homo erectus left Africa and spread to Asia. There is no evidence that such a coincidence indicates the superiority of the hominin or that it was the special bearer of rationality. By that time the other hominins had nearly disappeared, but others were to follow, who would take up both the Olduwan and Acheulian traditions.

At between 1 MYA and .5 MYA Homo erectus entered Europe with Olduwan tools. By .5 MYA, the tradition had been fairly well distributed over the eastern hemisphere. When it stopped being used is unclear. Discounting neo-Olduwan, it is probably safe to say it was mainly gone by .25 MYA.

[edit] The tools

[edit] Manufacture of the tools

To obtain an Olduwan tool, a roughly spherical hammerstone is struck on the edge, or striking platform, of a suitable core rock to produce a conchoidal fracture with sharp edges useful for various purposes. The process is often called lithic reduction. The chip removed by the blow is the flake. Below the point of impact on the core is a characteristic bulb with fine fissures on the fracture surface. The flake evidences ripple marks.

The materials of the tools were for the most part quartz, quartzite, basalt, or obsidian, and later flint and chert. Any rock that can hold an edge will do. The main source of these rocks is river cobbles, which provide both hammer stones and striking platforms. The earliest tools were simply split cobbles. It is not always clear which is the flake. Later tool-makers clearly identified and reworked flakes.

The Olduwan tradition is the first known regular human exploitation of the sharp edge. Complaints that artifacts could not be distinguished from naturally fractured stone helped spark a careful study of the technique. It has been duplicated many times by moderns, making misidentification less likely. Unfortunately clandestine studies had already been undertaken by persons intent on fraud, such as the British swindler, Edward Simpson, or "Flint Jack."

Use of the point is also known from Swartkrans, as a bone shaft with a polished point was discovered there in Member (layer) I, dated 1.8-1.5 MYA. The Osteodontokeratic industry hypothesized by Raymond Dart is less certain.

As to whether these tools can be called "rude" or "crude" is a matter of the archaeologist's value system. Archaeologists of the 19th and early 20th century tended to interpret with some prejudice, as is evidenced by their language. For example, one might have chosen the words "elegant" or "natural" with equal validity. The words "simple" or "complex" can be used with more objectivity, as there is a gradual but clear tendency toward increasing complexity. At the end of the Stone Age, the supposedly primitive stone tools were so fine that they were imitated in metal.

[edit] Shapes and uses of the tools

Mary Leakey classified the Olduwan tools as Heavy Duty, Light Duty, Utilized Pieces and Debitage, or waste.^[2] Heavy-duty tools are mainly cores. A chopper has an edge on one side. It is unifacial if the edge was created by flaking on one face of the core, or bifacial if on two. Discoid tools are roughly circular with a peripheral edge. Polyhedral tools are edged in the shape of a polyhedron. In addition are spheroidal hammer stones.

Light-duty tools are mainly flakes. There are scrapers, awls (with points for boring) and burins (with points for engraving). Some of these functions belong also to heavy-duty tools. For example, there are heavy-duty scrapers.

Utilized pieces are tools that began with one purpose in mind but were utilized opportunistically.

Olduwan tools were probably used for many purposes, which have been discovered from observation of modern apes and hunter-gatherers. Nuts and bones are cracked by hitting them with hammer stones on a stone used as an anvil. Battered and pitted stones testify to this possible use.

Heavy-duty tools could be used for wood-working, in the function of an axe. Both choppers and large flakes were probably used for this purpose. Once a branch was separated, it could be scraped clean with a scraper, or hollowed with the pointed tools. Such uses are attested by characteristic microscopic alterations of edges used to scrape wood.

If stone tools were valuable for working wood, they were invaluable for preparing hide. The hide must be cut by slicing, pierced and scraped clean of residues. Hides could be used for clothing, shelters or containers. The rest of the animal also had to be butchered, for ease of consuming, and probably the convenience in carrying and perhaps distributing the meat. Flakes are most suitable for the purpose.

In addition, pointed bones or sticks were probably used for digging for roots and tubers. Wood branches were probably used for missiles and clubs. Branches were woven into shelters or sleeping nests.

Hypotheses on Olduwan tool use have gone past the point of mere guess-work. Lawrence Keeley, following in the footsteps of Sergei Semenov, conducted microscopic studies (with a high-powered optical microscope) on the edges of tools manufactured de novo and used for the originally speculative purposes described above. He found that the marks were characteristic of the use and matched marks on prehistoric tools. Studies of the cut marks on bones using an electron microscope produce a similar result.

[edit] The Acheulian equivocation

The French anthropologists who initiated the study of prehistoric tools defined the Abbevillian stage to precede the Acheulian. Tools were vaguely defined by type, such as "handaxe". With the discovery of an increasing variety of primitive tools, a certain difficulty in defining them appeared. What was the difference between Abbevillian and Acheulian? Scientists were not sure any more. The reader may find considerable verbal backtracking and hunting about in the literature. Anthropologists of the times tended to use date to label an artifact. Early Paleolithic implied Olduwan; middle, Acheulian.

In the late 20th century, discovery of the discrepancies in date caused a crisis of definition. If Abbevillian did not necessarily precede Acheulian and both traditions had flakes and bifaces, how was the difference to be defined? It was in this spirit that many artifacts formerly considered Abbevillian were labeled Acheulian. In consideration of the difficulty, some preferred to name both phases Acheulian. When the topic of Abbevillian came up, it was simply put down as a phase of Acheulian. Whatever was from Africa was Olduwan, and whatever from Europe, Acheulian.

The solution to the definition problem is stated in the article on Acheulian. The difference is to be defined on complexity. Simply struck tools are Olduwan. Retouched, or reworked tools are Acheulian. Retouching is a second working of the artifact. The manufacturer first creates an Olduwan tool. Then he reworks or retouches the edges by removing very small chips so as to straighten and sharpen the edge. Typically but not necessarily the reworking is accomplished by pressure flaking.

The pictures in the introduction to this article are mainly labeled Acheulian, but this is the now false Acheulian, which also includes Abbevillian. The artifacts shown are clearly in the Olduwan tradition. One or two of the more complex bifaces may have edges made straighter by a large percussion or two, but there is no sign of pressure flaking as depicted. The pictures included with this subsection show the difference.

[edit] The tool users

Current anthropological thinking is that Olduwan tools were made by both Australopithecus and Homo; in other words, all the hominins of the times. In that case, tool manufacture cannot be a genotype tied to a single species. Rather, it reflects some sort of general ability. All the hominins shared in whatever technology was available to them. The concept of general technological advance, in this view, has applications that predate modern man.

Before sufficient evidence existed to reach the above conclusion, anthropologists tended to seek one, culture-bearing species as the sole innovater of tools. The main candidate was Homo habilis, an early species of Homo, who was named "skillful" for the facility. The guiding theory of this time was that the fossils which seemed to be closer to modern humans in more traits were probable human ancestors, and that they should have some selective advantage that would lead to their descendants surviving while other lineages of bipedal primate became extinct. Thus "tool use" seemed to be a very likely candidate.

Currently the evidence has gone beyond a narrow application of the select species interpretation. First, it is not clear that only direct human ancestors used early stone tools. Second, there is less of a clear "sequence" of gradually improving tools. Finally, the proliferation of labelled species seems to indicate that there were many more branches. When the prevailing view was that a more gracile set of forms looking more like modern humans competed with more "robust" forms with larger jaws, it seemed more reasonable to assume that smaller jaws created a greater role for tool making, which allowed more human-like adaptation, and thus more need for tool use; however, with many different groups, such a simple feedback loop no longer seems to explain all of the available observations. Biologists such as Stephen Jay Gould argued that even looking for exact deterministic reasons for evolutionary winners and losers was a false occupation, since events too small to be observed could have determined which groups survived and which groups did not.

According to Gould's view, during the Plio-Pleistocene, there would have been no way to single out a specific hominin as "advanced" or predict that one day his descendants would be us.^[3] Events might have turned out some other way. There is no scientific necessity for us to be here, and our being here does not require some special hominin. The influence of early ideas on race, which spilled over into species (the ancients did not distinguish), also required the presence of a special ancestor. In the former "race" concept, a given type was endowed with inalienable characteristics that were diagnostic of the type. You could therefore identify the type from a single instance.^[4] If man is to be defined as a rational animal (and the only rational animal), and culture, including tools, is an aspect of rationality, then there must have been a single type ancestor of rationality. Whatever was not man was not rational.

The search for a clear linear descent of human beings with predestined survival was associated in the 20th century the search for "the missing link", which Homo habilis was thought to be. Such a view excluded any other animal from culture and tools. It did leave the scientists open to legitimate criticism from the opponents of evolution: if the other primates and the supposed ancestor of man were not human, they were not rational and could not have been the source of rationality.

There have been some recent controversial experiments to teach chimpanzees and gorillas, such as the celebrated Koko, to sign in American Sign Language. The results are contested. If the apes are really communicating in sign language and are not just gesturing, then they evidence conscious personality and some ability to reason. If they are not signing, there is still the question of their social behavior, which indicates consciousness and reason. Other animals, such as dolphins and elephants, have given similar indications.

There is presently no evidence to show that Olduwan tools were the sole property of the Homo line or that the ability to produce them was the special characteristic of only our ancestors. There is reason to think that the ancestor of chimpanzees and men had a facility for tool making: an experimental subject, Kanzi was taught the art of making Olduwan tools.

[edit] Olduwan Culture

Animals who live in open terrain can be more easily seen by predators and are more subject to predation. Social animals have grouping together as their main defensive strategy. Grouped animals can watch each others' backs, sound the alarm, fight together, cause confusion together, forage together and huddle together against the cold. For example, at the first sign of danger, zebras may run off, or they may stand and fight in a cluster with some facing backward. Nearly all the Primates live and fight in bands. It would be highly unusual if the early hominins did not.

Human societies differ from those of the other primates in being consciously elaborate; that is, in possessing social structures with recognized degrees of consanguinity and affinity. How far did Olduwan hominins go in this direction? Reconstruction over such a distance is difficult, and is the subject of a great deal of debate. The basis of all mammalian grouping is the kin-selected group. The hominins almost certainly would have lived and hunted with their kin and mates, as do chimpanzees. Chimpanzees do not recognize their kin as such.

One of the centers of argument about what kind of society the Olduwan period tool makers had centers on their strategies for foraging and sleeping. In the early 1970's Glynn Isaac touched off a debate by proposing that hominins of this period had a "home base" and they foraged outward from it, returning with high value food to share to be processed. Over the course of the last 30 years, a variety of competing theories about how foraging occurred have been proposed, each one implying certain kinds of social strategies. The available evidence from the distribution of tools and remains is not enough to decide which ones are the most likely. However, three main groups of theories predominate. Isaac's model became the "central foraging point", as he responded to criticisms that he had imputed too much modern behavior into the early hominins, with relatively free form searches outward. A second group of models took modern chimpanzee behavior as a starting point, having the hominins use relatively fixed routes of foraging, and leaving tools where it was best to do so on a constant track. A third group of theories had relatively loose bands scouring the range, taking care to move carcasses from dangerous death sites and leaving tools more or less at random. Each implies different grouping and social strategies, from the relative altruism of central base models to the relatively disjointed search models. (See also central foraging theory, scavenging station model, Lewis Binford)

The makers of Olduwan tools were mainly right-handed. "Handedness" (lateralization) had already evolved, though it is not clear how related to modern lateralization it was, since other animals show handedness as well.

Most models rely on social and communication networks to hold the band together. These social networks range form requiring no more communication than modern primates, to requiring more sophisticated sharing and teaching. At present, there has been no evidence that sharply divides these theories.

Hominins probably lived in social groups that had contact with others. This conclusion is supported the large number of bones at many sites, too large to be the work of one individual, and all of the scatter patterns implying many different individuals. Since modern primates in Africa have fluid boundaries between groups, as individuals enter, become the focus of bands, and others leave, it is also probable that the tools we find are the result of many overlapping groups working the same territories, and perhaps competing over them. Because of the huge range of time and species associated with possible Olduwan tools, it is difficult to be more precise than this, since it is almost certain that different social groupings were used at different times and different places.

As the Olduwan period moves forward, it is probable that the home base form became more prevalent and eventually dominant. Heat-blackened artifacts and baked clay at the 20 east site of Koobi Fora, and fire-blackened bones at Swartkrans, both from 1.5 MYA, indicate the possible presence of the camp fire, though it is still not clear how developed pyroculture was at this time. A circle of stones at site DK in Bed I at Olduvai indicates a possible shelter. By 750K, patches of fire use are found outside of Africa. Fire creates a more powerful center of gravity, as does the continuous inhabitation of caves and other forms of natural shelter.

There is also the question of what mix of hunting, gathering and scavenging the tool users employed. Early models focused on the tool users as hunters. The animals butchered by the tools include waterbuck, hartebeest, Springbok, pig and zebra. However, the disposition of the bones allows some question about hominin methods of obtaining meat. That they were omnivores is unquestioned, as the digging implement and the probable use of hammer stones to smash nuts indicate. Lewis Binford first noticed that the bones at Olduvai contained a disproportionately high incidence of extremities, which are low in food substance. He concluded other predators had taken the best meat, and the hominins had only scavenged. The counter view is that while hunting many large animals would be beyond the reach of an individual human, that groups could bring down larger game, as pack hunting animals are capable of doing. Moreover, since many animals both hunt and scavenge, it is possible that hominis hunted smaller animals, but were not above driving carnivores from larger kills, as they probably were driven from kills themselves from time to time.

[edit] Notes

1. ^ Ironically, many scientists had drawn the erroneous conclusion that Homo habilis was the predator, using Olduwan tools. The higher percentage of primate bones was interpreted as a kind of cannibalism, feeding the imagination of Raymond Dart. Brain discovered that the source of the stripping and chewing of the bones was the leopard. Evidently, the architects of the Olduwan industry were not yet a match for prehistoric predators.
2. ^ There is a good online summary of Mary's classification on Effland's site for Anthropology ASB22 at Mesa Community College in Arizona, apparently written by Effland.
3. ^ Richard Leakey points out the difference between the "old simplistic view of human evolution" and the "modern, biologically realistic view", quoting from Gould, in The Making of Mankind, Page 71 of the Dutton 1981 hardcopy.
4. ^ Ashley Montagu published a philosophic review of the concept of race, especially as it appears in biological science of the last 500 years, in two articles (Chapters 1 & 2) of The Concept of Race, Copyright 1964, Collier-MacMillan Limited. In them he opposes the survival of the Aristotelian concept of species in such concepts as Cuvier's "Unity of Type" and "Fixity of Species."

[edit] Sources

• Braidwood, Robert J., Prehistoric Men, many editions.
• Domínguez-Rodrigo, M., T. R. Pickering, S. Semaw, and M. J. Rogers. 2005. Cutmarked bones from Pliocene archaeological sites at Gona, Afar, Ethiopia: Implications for the function of the world's oldest stone tools. Journal of Human Evolution 48:109-121.
• Edey, Maitland A., The Missing Link, Time-Life Books, 1972.
• Schick, Kathy D.; Toth, Nicholas, Making Silent Stones Speak', Simon & Schuster, 1993, ISBN 0-671-69371-9
• Semaw, Sileshi, 2000: The worlds oldest stone artefacts from Gona Ethiopia: Their implications for understanding stone technology and patterns of human evolution between 2.6-1.5 million years ago, Journal of Archaeological Science, 27: 1197-1214.
• Isaac, Glynn and Harris, JWK The Scatter between the Patches 1975
• Isaac, Glynn The Food Sharing Behavior of Protohuman Hominids Scientific American 238(4):90-108. 1978
• Binford, Lewis Searching for Camps and Missing the Evidence: Another Look at the Lower Paleolithic 1987
• Toth, Nicholas The Oldowan reassessed: a close look at early stone artifacts Journal of Archaeological Science 1985

[edit] External links

• Oldowan Pebble Handaxes of Europe
• Oldowan Flake Tool
• Stone Age Hand-axes
• Early Palaeolithic
• STONE AGE REFERENCE COLLECTION
• Microwear polishes on early stone tools from Koobi Fora, Kenya, article in Nature 293, 464 - 465 (08 October 1981). The summary and the references are displayed at no charge at the Nature site.
• AN APE'S VIEW OF THE OLDOWAN, T. Wynn and W.C. McGrew, Man 24:383-398; 1989.
• Flaked Stones and Old Bones: Biological and Cultural Evolution at the Dawn of Technology, Thomas Plummer, YEARBOOK OF PHYSICAL ANTHROPOLOGY 47:118–164 (2004).