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.
