The document discusses the Mitochondrial Eve Theory, which proposes that all living humans can trace their mitochondrial DNA back to a single female individual, known as Mitochondrial Eve. She is believed to have lived around 100,000-200,000 years ago in Africa. Researchers used mitochondrial DNA comparisons to construct family trees linking all modern humans to ancestral lines originating in Africa. The theory helps explain human evolution and migration patterns out of Africa by proposing a genetic "bottleneck" that reduced early human populations.