How does mitochondrial DNA aid in tracing human ancestry?

Mitochondrial DNA (mtDNA) is a valuable tool for tracing human ancestry primarily because it reflects maternal lineage. This is due to the unique way in which mtDNA is inherited; it is passed down exclusively from mother to offspring. As a result, all individuals inherit their mtDNA from their mothers, allowing researchers to trace maternal genetic lines over generations.

Furthermore, this uniparental inheritance pattern means that changes and mutations in mtDNA can serve as markers for familial connections and migration patterns of ancient human populations. By analyzing the similarities and differences in mtDNA sequences among individuals and populations, scientists can reconstruct migration routes and demographic history, painting a picture of how modern humans have spread across the globe.

In contrast, mitochondrial DNA is not inherited from both parents, nor is it identical in all humans, as there are variations in mtDNA sequences that can signify different lineages. Additionally, mtDNA does not trace paternal lineage, which is typically analyzed through Y-chromosome DNA. This unique combination of characteristics makes mtDNA especially useful for understanding our maternal ancestry and the migration patterns of our ancestors.