From prehistoric times to 1000 ce, the creation and use of tools with sharp edges was one of the pivotal developments in technology. When exactly early humans started sharpening rocks into cutting tools is unclean but rudimentary hand axes—rocks with one end sharpened and the other shaped to fit into a hand— were first used up to two and a half million years ago in Africa and the Middle East. Such tools were not only useful for everyday jobs, such as scraping meat off bones, but also served as potential weapons against human adversaries. These blades were made by pressure flaking—a process of hitting a rock with a piece of horn or antler until its edge became jagged—and were surprisingly sharp. Using this simple method, prehistoric man made many practical tools such as stone blades, particularly those made from flint, with smooth or serrated edges. However, a further step was required to transform the stone blade into a true fighting weapon.
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