Stone Age
Oldowan in Africa

The earliest documented stone tools have been found in eastern Africa, manufacturers unknown, at the 3.3 million-year-old site of Lomekwi 3 in Kenya. Better known are the later tools belonging to an industry known as Oldowan, after the type site of Olduvai Gorge in Tanzania.

The tools were formed by knocking pieces off a river pebble, or stones like it, with a hammerstone to obtain large and small pieces with one or more sharp edges. The original stone is called a core; the resultant pieces, flakes. Typically, but not necessarily, small pieces are detached from a larger piece, in which case the larger piece may be called the core and the smaller pieces the flakes. The prevalent usage, however, is to call all the results flakes, which can be confusing. A split in half is called bipolar flaking.

Consequently, the method is often called "core-and-flake". More recently, the tradition has been called "small flake" since the flakes were small compared to subsequent Acheulean tools.

The essence of the Oldowan is the making and often immediate use of small flakes.

Another naming scheme is "Pebble Core Technology (PBC)":

Pebble cores are... artifacts that have been shaped by varying amounts of hard-hammer percussion.

Various refinements in the shape have been called choppers, discoids, polyhedrons, subspheroid, etc. To date no reasons for the variants have been ascertained:

From a functional standpoint, pebble cores seem designed for no specific purpose.

However, they would not have been manufactured for no purpose:

Pebble cores can be useful in many cutting, scraping or chopping tasks, but... they are not particularly more efficient in such tasks than a sharp-edged rock.

The whole point of their utility is that each is a "sharp-edged rock" in locations where nature has not provided any. There is additional evidence that Oldowan, or Mode 1, tools were used in "percussion technology"; that is, they were designed to be gripped at the blunt end and strike something with the edge, from which use they were given the name of choppers. Modern science has been able to detect mammalian blood cells on Mode 1 tools at Sterkfontein, Member 5 East, in South Africa. As the blood must have come from a fresh kill, the tool users are likely to have done the killing and used the tools for butchering. Plant residues bonded to the silicon of some tools confirm the use to chop plants.

Although the exact species authoring the tools remains unknown, Mode 1 tools in Africa were manufactured and used predominantly by Homo habilis. They cannot be said to have developed these tools or to have contributed the tradition to technology. They continued a tradition of yet unknown origin. As chimpanzees sometimes naturally use percussion to extract or prepare food in the wild, and may use either unmodified stones or stones that they have split, creating an Oldowan tool, the tradition may well be far older than its current record.

Towards the end of Oldowan in Africa a new species appeared over the range of Homo habilis: Homo erectus. The earliest "unambiguous" evidence is a whole cranium, KNM-ER 3733 (a find identifier) from Koobi Fora in Kenya, dated to 1.78 mya. An early skull fragment, KNM-ER 2598, dated to 1.9 mya, is considered a good candidate also. Transitions in paleoanthropology are always hard to find, if not impossible, but based on the "long-legged" limb morphology shared by H. habilis and H. rudolfensis in East Africa, an evolution from one of those two has been suggested.

The most immediate cause of the new adjustments appears to have been an increasing aridity in the region and consequent contraction of parkland savanna, interspersed with trees and groves, in favor of open grassland, dated 1.8–1.7 mya. During that transitional period the percentage of grazers among the fossil species increased from around 15–25% to 45%, dispersing the food supply and requiring a facility among the hunters to travel longer distances comfortably, which H. erectus obviously had. The ultimate proof is the "dispersal" of H. erectus "across much of Africa and Asia, substantially before the development of the Mode 2 technology and use of fire...." H. erectus carried Mode 1 tools over Eurasia.

According to the current evidence (which may change at any time) Mode 1 tools are documented from about 2.6 mya to about 1.5 mya in Africa, and to 0.5 mya outside of it. The genus Homo is known from H. habilis and H. rudolfensis from 2.3 to 2.0 mya, with the latest habilis being an upper jaw from Koobi Fora, Kenya, from 1.4 mya. H. erectus is dated 1.8–0.6 mya.

According to this chronology Mode 1 was inherited by Homo from unknown Hominans, probably Australopithecus and Paranthropus, who must have continued on with Mode 1 and then with Mode 2 until their extinction no later than 1.1 mya. Meanwhile, living contemporaneously in the same regions H. habilis inherited the tools around 2.3 mya. At about 1.9 mya H. erectus came on stage and lived contemporaneously with the others. Mode 1 was now being shared by a number of Hominans over the same ranges, presumably subsisting in different niches, but the archaeology is not precise enough to say which.
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