Geoscience Reference
In-Depth Information
17.3 Stone Age cultures and prehistoric stone tools
Klein (
1989
) has pointed out that stone tools are defined primarily on the basis of
their shape and not their actual function, about which we can often only surmise,
and so it is very hard to infer former human behaviour purely on the basis of stone
tool morphology. To do this more convincingly, we need to draw on the evidence
left by tool-use wear and by plant and animal residues on the cutting edges of stone
tools, supplemented by tool-making and tool-use experiments designed to test any
propositions arising from the purely archaeological remains (Keeley,
1980
; Keeley
and Toth,
1981
; Schick and Toth,
1995
). Ethnographic evidence derived from mod-
ern hunter-gatherer societies provides another fruitful means of formulating testable
hypotheses or models of past human behaviour (Clark,
1980
). Needless to say, not
all tools are made of stone. Observations of wild chimpanzee behaviour suggest that
the early hominid use of sticks for digging and of sticks and other plant materials for
making nests or shelters was likely (Goodall,
1976
). The use of fire-hardened wooden
spears may extend well back in the prehistoric record, although suitable conditions
for their preservation are rare (Clark,
1969
), and hafting stone points to wooden shafts
to make spears has a respectable antiquity of around 500,000 years in southern Africa
(Wilkins et al.,
2012
), which is 200,000 years more than had been previously thought
(e.g., Ambrose,
2001
).
The earliest stone tools are pebbles from which several flakes have been struck.
These pebble tools (
Figure 17.3
) are found across Africa, and the oldest ones presently
known (2.6-2.5 Ma) come from the Gona Valley in the Afar Desert of Ethiopia on
the left bank of the Awash River, where they have been dated using a combination of
geomagnetic polarity stratigraphy and argon/argon dating of vitric tephra beds (Semaw
et al.,
1997
). These tools show evidence of several generations of flake scars, and the
'large number of well struck flakes with conspicuous bulbs of percussion' indicates
that the toolmakers had 'a clear understanding of conchoidal fracture mechanics'
(Semaw et al.,
1997
, p. 335). At Hadar on the left bank of the Awash River, stone tools
and
Homo
fossils occur together and have an age of 2.33
0.07 Ma (Kimbel et al.,
1996
). The name given to this pebble tool tradition is
Oldowan
from their early
discovery at Olduvai Gorge in Tanzania by Mary and Louis Leakey, where they were
dated to around 1.8 Ma (Leakey et al.,
1961
; Evernden and Curtis,
1965
).
About 1 million years after the inception of stone tool-making at around 2.5 Ma,
and apparently quite abruptly at 1.6-1.5 Ma ago, our hominid ancestors contrived to
detach large flakes about 15-20 cm long from big blocks of rock (Ambrose,
2001
).
These flakes were then struck with a stone hammer, either on both sides or on a
single side, to form a bifacially or unifacially worked large stone flake, termed a
biface or a uniface. A biface with a point at one end is often called a hand-axe; those
with a chisel-like edge are called cleavers. Together with flakes and spheroids, they
characterise what is known as the
Acheulian
cultural tradition (
Figure 17.3
), from the
±
