Some chimpanzee
communities are known to use stone and wood as hammers to crack
nuts and as crude ineffective weapons. However, they have not been
observed systematically shaping them to increase their
efficiency. The most sophisticated chimpanzee tools are
small, slender tree branches from which they strip off the
leaves. The twigs are then used as probes for some of their
favorite foods- -termites and ants. It is likely that the
australopithecines were at least this sophisticated in their simple
tool use.
The first
unquestionable stone tools were probably made and used by early
transitional humans in East Africa 2.6- 2.5 million years
ago. While the earliest sites with these tools are from the
Gona River Region of Ethiopia, simple tools of this kind were first
discovered by Mary and Louis Leakey associated with Homo habilis at
Olduvai Gorge in Tanzania. Hence, they were named Oldowan
tools after that location.
There were two main
categories of tools in the Oldowan Tradition. There were
stone cobbles with several flakes knocked off usually at one end by
heavy glancing percussion blows from another rock used as a
hammer. This produced a jagged, chopping or cleaver-like
implement that fits easily in the hand. These core tools most
likely functioned as multipurpose hammering, chopping, and digging
implements. Probably the most important tools, were
sharp-edged stone flakes produced in the process of making the core
tools. These simple flake tools were used without further
modification as knives. They would have been essential for
butchering large animals, because human teeth and fingers are
totally inadequate for penetrating thick skins and removing pieces
of meat. Some paleoanthropologists have suggested that the
core tools were, in fact, only sources for the flake tools and that
the cores had little other use.
In addition to stone
tools, Homo habilis very likely made simple implements out of wood
and other highly perishable materials that have not survived.
In the 1940's, Raymond Dart claimed that australopithecines and
early humans also used the hard body parts of animals as clubs and
other sorts of weapons. He proposed an entire tool making
tradition called Osteodontokeratic , based on the presumed use of
bones, teeth, and horns. This idea has been rejected by most
paleoanthropologists today since there is a lack of evidence for
the systematic, shaping or even use of these materials for weapons
or other types of tools at this early time. In addition, it
is unlikely that the earliest humans were aggressive hunters.
They most likely were primarily vegetarians who occasionally ate
meat that was mostly scavenged from the leftovers of kills
abandoned by lions, leopards, and other large predators. At
times, they also may have hunted monkeys and other small game much
as chimpanzees do today.
Homo habilis
continued to make and use stone tools in the Oldowan Tradition for
nearly a million years but with gradual improvements. By
1.6-1.4 million years ago, the skills of some of their Homo erectus
descendants had increased to the point that they were making more
sophisticated tools with sharper and straighter edges. Their
tool kits were sufficiently advanced to consider them to be from a
new tool making tradition now referred to as Acheulean .
Perhaps, the most important of these new tools were hand axes or
bifaces. They were rock cores or large flakes that were
systematically worked by percussion flaking to an elongated oval
shape with one pointed end and sharp edges on the sides. In
profile, they usually had a teardrop or broad leaf shape.
Referring to these artifacts as hand axes may be misleading since
we do not know for sure whether they were primarily axes in a
modern sense or even if they were held in the hand. Very
likely, they were multipurpose implements used for light chopping
of wood, digging up roots and bulbs, butchering animals, and
cracking nuts and bones. In a sense, they were the Swiss Army
knives of their times.
Some of the
Acheulean tools were shaped by additional percussion flaking to
relatively standardized forms. For instance, the surfaces of
late Acheulean hand axes often had many relatively small flake
scars indicating that these tools were not completely made with
heavy hammerstones. Late transitional Homo erectus or their
immediate successors must have begun using softer hammers for
greater control in the final shaping process. Pieces of hard
wood, antler, or bone would have functioned well for this
purpose.
While hand axes were
the most diagnostic of Acheulean tools, they usually make up only a
small percentage of the artifacts found at Homo erectus
sites. In fact, these early humans made a relatively wide
variety of stone tools that were used for processing various plant
and animal materials. Their tool kits included choppers,
cleavers, and hammers as well as flakes used as knives and
scrapers. It is quite likely that Homo erectus also made many
implements out of more perishable materials such as wood, bark, and
even grass.
The Acheulean
Tradition of tool making apparently began in East Africa 1.6-1.4
million years ago and spread into Southwest Asia and Europe by at
least 600,000 years ago. Until recently, the lack of hand
axes at Zhoukoudian and other East Asian Homo erectus sites
suggested that the Acheulean Tradition did not reach that
far. It was thought likely that the same functions that hand
axes performed in the west were being performed by other kinds of
tools in the far East. However, 24 sites in Southern China
have now been found to contain Acheulean hand axes dating back
800,000 years.
Throughout most of
the Homo erectus geographic range, there is clear evidence of
progressive improvement in tool making over time. The late
Homo erectus had more complex mental templates guiding them in the
manufacture of their artifacts. In addition, the
reliance on tools increased as the implements became more
useful. By 400,000 years ago, major Homo erectus sites
commonly had tens of thousands of stone tools.
