Final answer:
All living humans are descended from a woman, termed Mitochondrial Eve, who lived in Africa around 200,000 years ago, according to mtDNA evidence. She represents our most recent common ancestor through the maternal line, with this evidence drawn from the patterns observed in mtDNA mutations.
Step-by-step explanation:
According to evidence gathered from mitochondrial DNA (mtDNA), it is believed that all living humans are descended from a single female. This ancestor, often referred to as Mitochondrial Eve, is not the very first human female but our most recent common ancestor through maternal lines. Researchers estimate that she lived approximately 200,000 years ago in Africa. This conclusion is drawn from the fact that mutations in mtDNA occur at fairly regular intervals, which allows scientists to trace genetic lineages back to a single source.
The continuity of mtDNA occurs because it is passed down from mothers to their offspring without recombination, which means that the mtDNA you have is a unique copy of your mother's, differing only due to rare mutations. Over time, the maternal lines that did not produce female offspring, or whose descendants died childless, ceased to carry forward their mtDNA, narrowing the genetic pool back to the successful lineage of Mitochondrial Eve.
Moreover, the study of human lice and other small organisms suggests examples of coevolution, providing additional insight into the human story. The understanding of when different human populations began to diverge is fundamental to molecular anthropology. The use of mtDNA in research is crucial because it mutates faster than nuclear DNA, allowing for the tracking of human evolution over shorter periods, such as 200,000 years.