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.
Middle Stone Age
There have been two migration events out of Africa, the first was the expansion of "H. erectus" into Eurasia approximately 1.9 to 1.7 million years ago, and the second, by "H. sapiens" began during the MSA by 80 – 50 ka MSA out of Africa to Asia, Australia and Europe. Perhaps only in small numbers initially, but by 30 ka they had replaced Neanderthals and "H. erectus". Each of these migrations represent the increased flexibility of the genus "Homo" to survive in widely varied climates. Based on the measurement of a large number of human skulls a recent study supports a central/southern African origin for "Homo sapiens" as this region shows the highest intra-population diversity in phenotypic measurements. Genetic data supports this conclusion. However, there is genetic evidence to suggest that dispersal out of Africa began in eastern Africa. Sites such as the Omo Kibish Formation, the Herto Member of the Bouri Formation, and Mumba Cave contain fossil evidence to support this conclusion as well.