Agriculture was unknown during mankind's early existence, as were other complex activities like pottery or metallurgy. For close on three quarters of man's history, we human beings have broken rocks to make our tools, and that is why archaeologists study this technology in so much detail, so they can attempt to understand how societies used to live in the past.

Stone artefacts are really no more than a tiny fraction of the objects that were made and used by humans in the past, but many of the other materials they employed for the activities they engaged in and for making personal objects in order to survive were perishable, meaning that their remains decomposed with the passing of time. From bone, animal horns and wood they made needles, handles, hooks, harpoons and dart throwers. Well-preserved basketwork objects have occasionally been found, such as baskets and sandals, as have even some of the woolly skins they used to wear or to put on the floors of their homes like soft carpets.

The word 'artefact' refers to an object that has been made or manipulated by human beings so it can serve a specific purpose. Before we carry out a detailed study of rock artefacts, we might suppose that they are "primitive" and that they have been made simply, that they are mere stones, unrecognisable as being any different from those found in nature. But the remains left behind by the earliest hunters and gatherers show that they had mastered the techniques of working with stone. And it can only have been by building up experience that prehistoric man was able to recognise the qualities of different rocks, and therefore choose the best raw materials and techniques for working them.

The instruments that were used by the most ancient indigenous peoples on our continent varied, depending on the time and place. Different groups of humans, with differing cultures, knowledge and skills, in fact inhabited different regions at the same time. The archaeologists who search for these objects, photograph them and write down details about them, and then - only then - remove them from ancient archaeological sites, classify these remains according to patterns and systems which enable them to find out how they were made and what they were used for, and the cultural differences that existed in the community they relate to. They thus define categories or types of artefacts, and give names to different manufacturing techniques.

The basic technique that was used for making rock instruments consisted of taking a stone, bone or fire-hardened wooden hammer and hitting a piece of flint, chert, obsidian or other non-sandy rock which leaves sharp edges like glass when it breaks. The raw material was either hit directly, or alternatively a chisel was placed between it and the hammer for greater precision in getting splinters known as chips or elongated pieces in the form of sheets. The activity of striking a hard object against the raw material nodule or nucleus is called direct percussion, whereas when the hammer strikes a chisel made of hard horn or wood, this is referred to as indirect percussion.

A wide range of utensils was made, depending on how the nucleus was hit. Chips with a long cutting edge were used for slicing meat or cutting, shearing or degreasing skins, while ones ending in a point were used for piercing leather and the heavier, coarser ones for crushing, scraping or splitting wood and bone.

Once the different types of splinter had been obtained, these could also be carefully touched up by pressing a sharp-pointed instrument against the cutting edges in order to remove minor scale and flakes. The result was an even wider range of fine instruments like knives, engraving chisels and saws, not to mention the tips of spears that were capable of piercing the thick skin of a mastodon.

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