How did Stone Age people make sharp edges on stone tools?

Stone Age people created sharp edges on stone tools primarily through the removal of flakes from a stone matrix, a process known as flaking. This was achieved using three main techniques:1

• Percussion Flaking: This involved striking a stone block with a hammer made of stone, wood, or bone. The anvil method was a variation where the workpiece was struck against a stationary rock. Using a softer "hammer" like wood or antler allowed for more precise, thinner flakes, resulting in sharper, more uniform edges.12
• Pressure Flaking: Considered the most advanced method, this involved using a pointed instrument of bone, antler, or wood to pry off tiny flakes. This technique provided the greatest control and was often used for finishing touches or shaping implements.12
• Grinding and Polishing: During the Neolithic Period, people refined tools by rubbing them against an abrasive rock. This process removed the scars left by earlier chipping, creating a much keener edge and smoother surfaces that allowed for deeper penetration.3

By utilizing materials like flint and obsidian, which exhibit a sharp, shell-like (conchoidal) fracture, early humans were able to produce highly effective cutting tools.13