Using the mitochondrial DNA data from a sampling of people from various people groups, we are able to trace back, in the past, to find that there is one mother who is the mother of us all. Everyone who is now living on the earth inherits his or her mitochondrial DNA from that mother. She has been called the Mitochondrial Eve.
Since this mitochondrial Eve is now thought to live 150,000 years ago, much later than the earliest man types discovered; She is not thought to be the first human mother.
Rather, the mitochondrial Eve is thought to have lived in a time when the human population was experiencing a bottleneck. A bottleneck is a time when only a small number of individuals are living. This increases the chance that one mother's mitochondrial DNA might survive while all others are lost.