Final answer:
mtDNA is crucial in the study of modern human origins as it allows scientists to track maternal lineage back to a common ancestor and provides a timeline for human population divergences. Mitochondrial DNA also uncovers interbreeding between distinct human species and supports the Out of Africa theory.
Step-by-step explanation:
mtDNA, or mitochondrial DNA, is highly relevant to the debate over modern human origins because it allows researchers to trace maternal ancestry back to a common ancestor. Unlike nuclear DNA, mtDNA is passed down from mothers to their children without recombination, making it a stable genetic marker over generations. The Out of Africa theory is supported by mtDNA evidence, which suggests that all modern humans have a lineage that traces back to a single female ancestor known as Mitochondrial Eve or mtMRCA, who lived approximately 200,000 years ago in Africa. This ancestral lineage is supported by organized mutational patterns in mtDNA that provide a timeline for when human populations began to diverge.
Furthermore, the unique properties of mtDNA have also revealed the existence of other human species or subspecies, like the Denisovans, through the analysis of ancient remains. Interbreeding between Denisovans, Neanderthals, and modern humans has been evidenced through shared genetic markers in contemporary human populations. The study of mtDNA hence provides a crucial framework for understanding human evolutionary history, human migration patterns, and the relationship between different hominin species.