Humans have survived and become the dominant species on Earth as they are living, intelligent beings who apply their ingenuity in making and using tools. From the Stone Age on, humans fashioned an array of tools, of which blades were and are a primary implement. In the Stone Age, there were individuals who mastered the craft of knapping flint to form knives, spears and arrowheads for hunting and butchering game. In time, humans mastered metallurgy, fashioning knives, swords, spears and arrowheads first from bronze and finally iron. In ancient Mesoamerica, Mayans, Aztecs, Incas, fashioned blades from obsidian. In the present day, knives are mostly made from a blend of carbon steel and stainless steel. Knives are a common household item found in the kitchens in every home. Together with their use as common household items, knives are still used for hunting and warfare. With a sharp edge and pointed tip, the knife has to be handled with care. It can inflict a nasty wound if handled carelessly or with malice.