Mitochondrial DNA and human evolution.

Why mtDNA is useful

Because it comes down the maternal line, a tree of mtDNA types is a tree of mothers. Mutation accumulates fast enough, relative to many nuclear regions, to separate human groups on a recent timescale. Allan Wilson’s laboratory used this logic. In 1987 Rebecca Cann, Mark Stoneking and Wilson published the famous mitochondrial work that placed the common maternal ancestor of living humans in Africa.

Popular writing called her “mitochondrial Eve”. That name misleads if it sounds like the only woman of her time. She is the most recent woman from whom all living mtDNA lines descend. Many other women lived then; their mtDNA lines later died out.

What it showed about evolution

• Recent African origin: Living human mtDNA diversity is greatest in Africa, and non-African lineages sit inside African variation. This supported an Out-of-Africa model against a simple multiregional story of separate ancient origins.
• Haplogroups: Later work labelled maternal haplogroups that map dispersal into Eurasia, Australia and the Americas. They are tools for migration history, not races.
• Archaic cousins: Neanderthal and Denisovan mtDNA, when recovered, did not match living human mtDNA as a simple continuation. Nuclear DNA later showed some interbreeding. One locus is not the whole species tree.

Svante Pääbo’s ancient-DNA programme sits beside this note even though much of it is nuclear. It is the next chapter, not a substitute for the 1987 argument.

Limits

mtDNA is one locus. Selection, population size and drift can warp the tree. Time estimates depend on mutation-rate assumptions. Paternal leakage is rare. The bigger caution is that a maternal tree is not the full history of peoples. Y-chromosome and autosomal DNA must join it.

Commercial “maternal ancestry” tests report a haplogroup, not a caste or a civilisation.