In the "Tools" issue of Dragonfly, Nick Toth and Kathy Schick, who are experimental archaeologists, write about how they figured out how our ancient ancestors made tools by doing it themselves. They study the early Stone Age in a place called Koobi Fora, which is in Kenya, Africa. By making thousands of stone tools using many different methods, they figured out how early humans crafted their tools. For each method, they compared the tools they made with the ancient tools to see which kinds matched.
Humans began making stone tools, or lithics, even before they were modern Homo sapiens. The first stone tools, used by our human ancestors, were big rocks used for pounding, like you would use a hammer.
Ancient humans figured out that some kinds of rock break in a predictable way, and because of that predictability, they could shape the rock into different forms. Not all rocks break predictably, though. The rocks that work best for stone tool making are called siliceous rocks, which are rocks made of silicone dioxide. The most common type of siliceous rock used for stone tools is called chert or flint. Siliceous rocks break predictably because they have few impurities.
Chert can be shaped by either percussion flaking or pressure flaking , which are the oldest types of stone tool making. These were developed in a time archaeologists call the Paleolithic ("Old Stone") Period, which lasted over two million years.
This is how percussion flaking is done:
A core is struck by a hammerstone and a flake falls off. When the toolmaker uses the shaped core as a tool, it is called a core tool.
People also use the flakes to cut with. These are called flake tools.
In order to remove a flake off a piece of chert, the toolmaker applies a blow to a specific point on the rock, which is called a percussive blow. Because chert has few impurities, the energy spreads from the contact point outward without anything to stop it, in the shape of a cone. The energy moves in a wave and is called a conchoidal fracture pattern because from the side, the cone looks like a shell. This happens every time a toolmaker strikes a core with a hammerstone.
Another type of making stone tools is called pressure flaking. This method creates blade tools.
Here is pressure flaking:
By applying pressure in one direction with another rock, a long, thin flake is removed. This type of flake is called a blade.
The next time you use a knife or a fork, think about how those tools are part of a long chain begun by our distant ancestors, the prehistoric humans, two-and-a-half million years ago.
Remember: Making stone tools, or "flintknapping," is much harder to do than most people think, and it takes a lot of practice. It's also a lot of fun, but it can be dangerous. When you hit two stones together, very sharp pieces can fly off and seriously hurt you. Anyone who wants to make stone tools should do so only under the supervision of a skilled flintknapper.
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Dec. 10, 1997.
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