Final answer:
The estimated divergence of mtDNA lineages dates back to a common ancestor, known as Mitochondrial Eve, living about 100,000 to 200,000 years ago in Africa. Modern human mtDNA points to an ancestor about 160,000 years ago, while Y chromosome studies indicate about 140,000 years ago, with molecular clocks helping to measure these divergence times.
Step-by-step explanation:
The estimated divergence between two sets of mtDNA lineages can be traced back to a common ancestor by analyzing spontaneous mutations in mitochondrial DNA (mtDNA). This common ancestor, often referred to as the Mitochondrial Eve or mtMRCA, is believed to have lived in southern Africa about 100,000 to 200,000 years ago. The molecular clock technique utilizes DNA sequence variations to measure the time since two species diverged from a common ancestor, with the rate of mutations being relatively constant over time. The mtDNA evidence suggests that all modern humans' mtDNA comes from an ancestor who lived approximately 160,000 years ago in Africa, whereas the Y chromosome evidence indicates a common male ancestor from about 140,000 years ago.
To refine the molecular clock for the evolution of prokaryotes and other organisms, scientists may compare DNA or protein sequences, measuring mutation rates to determine evolutionary timelines. Through molecular anthropology studies and genetic markers such as mtDNA and the Y chromosome, molecular clocks can provide insight into our ancestors' histories and their divergence over time.