Ancient humans started down the path of evolving into two separate species before merging back into a single population, a genetic study suggests.
The genetic split in Africa resulted in distinct populations that lived in isolation for as much as 100,000 years, the scientists say. . . .
The latest conclusions are based on analysis of mitochondrial DNA in present-day African populations. This type of DNA is the genetic material stored in mitochondria - the "powerhouses" of cells.
It is passed down from a mother to her offspring, providing a unique record of maternal inheritance.
"We don't know how long it takes for hominids to fission off into separate species, but clearly they were separated for a very long time," said Dr Spencer Wells, director of the Genographic Project.
"They came back together again during the Late Stone Age - driven by population expansion." . . .
A major split occurred near the root of the tree as early as 150,000 years ago.
On one side of this divide are the mitochondrial lineages now found predominantly in East and West Africa, and all maternal lineages found outside Africa.
On the other side of the divide are lineages predominantly found in the Khoi and San (Khoisan) hunter-gatherer people of southern Africa.