Are we all descended from a common female ancestor?

In 1987, a group of genet­icists published a surprising study in the journal Nature.­ The­ researchers examined the mitochondrial DNA (mtDNA) taken from 147 people across all of today's major racial groups. These researchers found that the lineage of all people alive today falls on one of two branches in humanity's family tree. One of these branches consists of nothing but African lineage, the other contains all other groups, including some African lineage.
­Even more impressive, the geneticists concluded that every person on Earth right now can trace his or her lineage back to a single common female ancestor who lived around 200,000 years ago. Because one entire branch of human lineage is of African origin and the other contains African lineage as well, the study's authors concluded Africa is the place where this woman lived. The scientists named this common female ancestor Mitochondrial Eve.

(via Guy Kawasaki)