Normal age gap dating
The closest relative among the other living primates, the genus Pan, represents a branch that continued on in the deep forest, where the primates evolved.The rift served as a conduit for movement into southern Africa and also north down the Nile into North Africa and through the continuation of the rift in the Levant to the vast grasslands of Asia.The terms "Stone Age", "Bronze Age", and "Iron Age" were never meant to suggest that advancement and time periods in prehistory are only measured by the type of tool material, rather than, for example, social organization, food sources exploited, adaptation to climate, adoption of agriculture, cooking, settlement and religion.Like pottery, the typology of the stone tools combined with the relative sequence of the types in various regions provide a chronological framework for the evolution of man and society.The oldest sites containing tools are dated to 2.6–2.55 mya.One of the most striking circumstances about these sites is that they are from the Late Pliocene, where previous to their discovery tools were thought to have evolved only in the Pleistocene.
In Europe and North America, millstones were in use until well into the 20th century, and still are in many parts of the world.
The work of the archaeologist in determining the paleocontext and relative sequence of the layers is supplemented by the efforts of the geologic specialist in identifying layers of rock over geologic time, of the paleontological specialist in identifying bones and animals, of the palynologist in discovering and identifying plant species, of the physicist and chemist in laboratories determining dates by the carbon-14, potassium-argon and other methods.
Study of the Stone Age has never been mainly about stone tools and archaeology, which are only one form of evidence.
Stone Age artifacts include tools used by modern humans and by their predecessor species in the genus Homo, and possibly by the earlier partly contemporaneous genera Australopithecus and Paranthropus.
Bone tools were used during this period as well but are rarely preserved in the archaeological record.