Mitochondrial Eve

Mitochondrial Eve is a term from genetics and human evolution. It refers to a woman, whose mitochondrial DNA is a parent of all living humans. To put this more exactly, she is the female most recent common ancestor of all humans alive at present. 
How this is decided.
Rather than use full DNA comparisons, two simpler methods are used:
This gives haplogroups (a haplogroup is a combination of genes on different chromosomal regions that are closely linked and tend to be inherited together).
The results.
According to current research, Mitochondrial Eve lived about 200.000 years ago. Most likely she lived in East Africa, when "Homo sapiens sapiens" (anatomically modern humans) were developing as a population distinct from other human sub-species.
Mitochondrial Eve lived later than "Homo heidelbergensis" and the emergence of "Homo neanderthalensis", but earlier than the out of Africa migration.
The dating for 'Eve' was a blow to the multiregional hypothesis, and a boost to the hypothesis that modern humans originated relatively recently in Africa and spread from there, replacing more "archaic" human populations such as Neanderthals. As a result, the latter hypothesis became dominant.