Relative age dating rocks
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.
All the tools come from the Busidama Formation, which lies above a disconformity, or missing layer, which would have been from 2.9 to 2.7 mya.The transition from the Stone Age to the Bronze Age was a period during which modern people could smelt copper, but did not yet manufacture bronze, a time known as the Copper Age, or more technically the Chalcolithic, "copper-stone" age.The Chalcolithic by convention is the initial period of the Bronze Age. The transition out of the Stone Age occurred between 6000 BCE and 2500 BCE for much of humanity living in North Africa and Eurasia.gaps in the geological record." Innovation of the technique of smelting ore ended the Stone Age and began the Bronze Age.The first most significant metal manufactured was bronze, an alloy of copper and tin, each of which was smelted separately.Starting from about 4 million years ago (mya) a single biome established itself from South Africa through the rift, North Africa, and across Asia to modern China, which has been called "transcontinental 'savannahstan'" recently.
Starting in the grasslands of the rift, Homo erectus, the predecessor of modern humans, found an ecological niche as a tool-maker and developed a dependence on it, becoming a "tool equipped savanna dweller." Archaeological discoveries in Kenya in 2015, identifying possibly the oldest known evidence of hominin use of tools to date, have indicated that Kenyanthropus platyops ( a 3.2 to 3.5-million-year-old Pliocene hominin fossil discovered in Lake Turkana, Kenya in 1999 ) may have been the earliest tool-users known.
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 chief focus has always been on the society and the physical people who belonged to it.
Useful as it has been, the concept of the Stone Age has its limitations.
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.