The Single Origin Theory
The most popular theory of modern human origin begins in Africa. This theory contrasts with the regional development hypothesis, which claims that different groups of humans developed from different homo subspecies. The single origin theory has been gaining steam in anthropological circles since the 1980s, when studies of human mitochondrial DNA suggested an African birthplace of humanity. This evidence points a sort of “Eve”-like figure, a woman who is the ancestor of all modern humans. Mitochondrial DNA is traced through the maternal line of an organism. It stays relatively static, and is a useful means of testing for mutations in a line.
Looking at mitochondrial DNA of two separate organisms can show a sort of common link between the two, and specifically show the distance between that common link. It is through mitochondrial sequencing that we can tell that the most recent common ancestor of modern humans and chimpanzees was some 5-6 million years ago. We can also tell through this method that homo sapiens split off from Neanderthals some 4-500 thousand years ago. The alternate, multiregional hypothesis suggests one human species that has slowly grown from multiple subspecies into the modern human races.
This theory suggests that some of the variation present in modern humans comes from the varying subspecies and their interbreeding. One major problem with this multiregional hypothesis is a lack of genetic evidence. The differences between various groups of humans, at least on the genetic level is miniscule, significantly less than the differences within those groups. The single origin theory then, emerges as the most popular theory in the modern times. This leads to a sad truth, we as humans outcompeted and destroyed our closest relatives in the barbarism of our early expeditions away from our homes. As humans, we must carry some guilt for this genocide against our less well adapted cousins.