Middle Stone Age
The Middle Stone Age (or MSA) was a period of African prehistory between the Early Stone Age and the Later Stone Age. It is generally considered to have begun around 280,000 years ago and ended around 50–25,000 years ago. The beginnings of particular MSA stone tools have their origins as far back as 550–500,000 years ago and as such some researchers consider this to be the beginnings of the MSA. The MSA is often mistakenly understood to be synonymous with the Middle Paleolithic of Europe, especially due to their roughly contemporaneous time span, however, the Middle Paleolithic of Europe represents an entirely different hominin population, "Homo neanderthalensis", than the MSA of Africa, which did not have Neanderthal populations. Additionally, current archaeological research in Africa has yielded much evidence to suggest that modern human behavior and cognition was beginning to develop much earlier in Africa during the MSA than it was in Europe during the Middle Paleolithic. The MSA is associated with both anatomically modern humans ("Homo sapiens") as well as archaic "Homo sapiens", sometimes referred to as "Homo helmei". Early physical evidence comes from the Gademotta Formation in Ethiopia, the Kapthurin Formation in Kenya and Kathu Pan in South Africa.
Stone Age
In regions such as Sub-Saharan Africa, the Stone Age was followed directly by the Iron Age. The Middle East and southeastern Asian regions progressed past Stone Age technology around 6000 BCE. Europe, and the rest of Asia became post-Stone Age societies by about 4000 BCE. 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. The Americas notably did not develop a widespread behavior of smelting Bronze or Iron after the Stone Age period, although the technology existed. Stone tool manufacture continued even after the Stone Age ended in a given area. In Europe and North America, millstones were in use until well into the 20th century, and still are in many parts of the world.