Final answer:
Ancient DNA is usually studied using mtDNA because it is passed down through the maternal line and contains a mutational pattern that helps trace human genealogical lineage back to Mitochondrial Eve, allowing for detailed mapping of human evolutionary history.
Step-by-step explanation:
The ancient DNA studied is usually mtDNA because mtDNA is inherited strictly through the maternal line, making it invaluable for tracing genealogical lineage without the complications of genetic recombination seen in nuclear DNA. This molecular inheritance allows scientists to track and estimate the timeline of human population divergences and migrations.
Mutations in mtDNA occur at regular intervals, enabling the construction of a human family tree that leads back to an ancestral female, referred to as Mitochondrial Eve or mtMRCA (mitochondrial most recent common ancestor). This ancestral link is believed to be from a population that lived in Africa around 100,000-200,000 years ago.
Because of the absence of recombination and the relatively fast rate of mutation in mtDNA compared to nuclear DNA, researchers can use these mutations to map different branches of our maternal ancestry. The mutational pattern inherent in mtDNA is a crucial tool for molecular anthropologists in understanding human evolutionary history and mapping out the migratory paths of ancient humans.