My post about Mitochondrial Eve attracted a bunch of interest - thank you! - and several people asked a key question: what species was ME?
There is no direct evidence about ME at all - we have not found a fossil record of this particular individual. We can infer logically that she must have existed, and we can deduce approximately how long ago she lived from the amount of variation in Mitochondrial DNA (mtDNA) among present humans - about 200,000 years ago. This analysis also indicates the probable region in which she lived - East Africa.
From the age and region, we can deduce the species, see the following timeline:
As you can see, homo heidelbergensis was the direct ancestor species for homo sapiens. This species has been further divided into homo sapiens archaic and home sapiens modern; a distinction made based on recent fossil finds. The earliest human skulls were recently found in Ethiopia, dated about 160,000 years ago. ME was most likely homo sapiens archaic, although based on this date and region, it is possible she was an early homo sapiens modern. [ thanks to Dennis O'Neil for the diagram ]
It is interesting to speculate on the early history of ME and her ancestors. Was there a catastrophic event which eliminated many of ME's competitors, funneling the genetic ancestry through a single line? Perhaps ME migrated into a region which was spared from a climatic or other environmental event. Or perhaps ME embodied a mutation which conferred immunity from a particular disease. ME's daughters and granddaughters might have followed a single evolutionary path, living together in the same region and contributing to a common gene pool. Or perhaps one or more daughters split off, forming subspecies which ultimately died out.
It is suggestive that ME apparently lived right at the earliest time where the fossil record indicates the transition from H. sapiens archaic to H. sapiens modern. The family tree for ME must have contained thousands of branches which did not successfully make it to the present day, although we know from the very definition of ME that it does contain at least two which did!