A105 Lectures 20-21 November 10-12, 1997:
Early Archaeological record
Archaeologists study the record of material culture of ancient humans, including their tools, and the remains of their meals, housing, campsites, etc. While fossils are the preserved remains of living organisms, artifacts are the material products of ancient behavior, objects that were manufactured or modified by the hand of a hominid.
The earliest archaeological record is marked by the appearance of flaked stone artifacts, made by striking a fine-grained cobble of stone with a hard hammerstone. The cobblestone will fracture predictably (conchoidal fracture pattern), and a series of sharp-edged flakes of stone can be produced, leaving flake scars on the core, and battered ends on the hammerstone. When stone is flaked it produces a scatter of pieces, marking the spot where flaking activity took place. Similarly, if stone tools are dropped where they were used, they mark the location of hominid activities on the ancient landscape, and have been called "stone age visting cards."
Experiments with replicas of ancient artifacts have shown that the sharp edges of the flakes and the cores could have been useful for cutting a wide range of materials, from soft plant tissue to meat and leather. At many sites, stone tools have been found associated with bones of animals (large and small). The bones at some of these early sites, at Olduvai Gorge, for example, show evidence of having been damaged by stone tools (e.g. cutmarks from flakes and bashing marks to extract marrow from longbones with stone hammers), or carnivore teeth (e.g. hyenas chew on bones), or BOTH. Stone tools might have allowed early toolmakers to exploit a meat-eating savanna niche more effectively.
The earliest archaeological sites currently known have been found in East Africa between 2.5 and 2.0 million years ago; the oldest is the Gona site in the Hadar region of Ethiopia, dating to over 2.5 million years ago. Australopithecus africanus fossils have been found in South Africa from that time, and two new species of hominid, A. aethiopicus and Homo habilis appear in East Africa at that time as well (the earliest Homo come from several sites in East Africa dating to between 2.5 and 2.3 million years ago ... note that these are not mentioned in your textbook).
So, who was the stone tool maker in East Africa between 2.5 and 2.0 mya? You be the judge!
- circumstantial association of hominid fossils with artifacts does not help -- most archaeological sites have NO hominids in them. And BOTH A. boisei and H. habilis fossils have been found associated with artifacts. If anything, boisei fossils are much more common at stone tool sites than Homo fossils are because they are robust and preserve well. (Note that this fact contradicts a claim in your book!)
- all these hominids were upright and had "free hands" for tool use... finger bones from Olduvai suggest early Homo had human-like fingers and dexterity. Hand fossils of robust australopiths from South Africa suggest that they, too, had short fingers and the dexterity necessary for stone flaking. In fact, flaking experiments with chimps and bonobos demonstrate that even chimps can manipulate stones well enough to flake a core effectively.
- H. habilis had a larger brain than any australopithecine... yet even chimps can master the hand-eye coordination and problem-solving skills to flake cores today. Can A. boisei be excluded as a toolmaker based on brain size?
- H. habilis had smaller dentition and more gracile face than any previous hominid, suggesting that it either ate only soft foods (perhaps acquired with tools?) or used tools to process tough foods outside the mouth. On the other hand, do the chewing adaptations of A. boisei mean that it had no need for stone tools? With it's tiny front teeth, a cutting tool might have come in handy from time to time
WWW links to descriptions and images of early Hominid Fossils and Early Archaeology:
- Work at Lake Turkana! Koobi Fora Field School Web site
- Origins of Humankind site
- Fossil Hominids at the Talk_Origins archive
- Hominid Photo Gallery (examine pictures of fossils)
- Institute of Human Origins (Don Johanson)
- Earliest Stone Tools at the Gona site in the Hadar region of Ethiopia
Want a WWW change of pace?! Try the following links:
- Tom Weller's Science Made Stupid chapters on "Evolution" and the "Descent of Man"
- Explore the philosophy of technology, thought and evolution at the Principia Cybernetica Web site
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