The Stone Age began when some scrawny apelike creatures that walked upright started shaping rocks. These Paleolithic flintknappers first went to work on stone flake tools 3.39 million years ago. Knapping is the shaping of stone, such as flint, by chipping away bits.
The preservation of early stone works belies the fact that hominids manipulated various materials from their earliest days. Gorillas make nests to sleep in each night, and their hands are not nearly as dexterous as even the earliest hominid.
Organic materials simply would not have persevered to be part of the fossil record. Hence, although most implements made were of wood, the Stone Age was designated.