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.They serve as diagnostics of date, rather than characterizing the people or the 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.
Much of this study takes place in the laboratory in the presence of various specialists.
In experimental archaeology, researchers attempt to create replica tools, to understand how they were made.
Excavators at the locality point out that:"..earliest stone tool makers were skilled flintknappers ....
The possible reasons behind this seeming abrupt transition from the absence of stone tools to the presence thereof include ...The date range of this period is ambiguous, disputed, and variable according to the region in question.While it is possible to speak of a general 'stone age' period for the whole of humanity, some groups never developed metal-smelting technology, so remained in a 'stone age' until they encountered technologically developed cultures.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.The proto-Inca cultures of South America continued at a Stone Age level until around 2000 BCE, when gold, copper and silver made their entrance.