As mentioned in Section 9.3, mtDNA accumulates mutations at a rate approximately ten times faster than nuclear DNA. Thus geneticists can use mtDNA variations as a 'molecular clock' to study genetic variation and the movement of ancestral human populations from Africa to different areas of the world more than 125,000 years ago. Propose an explanation for how an analysis of mtDNA can be used to construct family trees of human evolution.

Key Concepts

Mitochondrial DNA (mtDNA)

Mitochondrial DNA is the genetic material found in mitochondria, the energy-producing organelles in cells. Unlike nuclear DNA, mtDNA is inherited maternally and has a higher mutation rate, making it useful for tracing lineage and evolutionary history. Its relatively rapid accumulation of mutations allows researchers to estimate the timing of evolutionary events and the relationships between different populations.

Molecular Clock

The molecular clock is a technique used in genetics to estimate the time of evolutionary events based on the rate of genetic mutations. By comparing the differences in mtDNA sequences among various populations, scientists can infer how long ago they diverged from a common ancestor. This method provides a timeline for human migration and evolution, helping to construct family trees that illustrate the relationships among different human groups.

Ancestral Human Populations

Ancestral human populations refer to the early groups of humans from which modern populations descended. Genetic studies of mtDNA can reveal patterns of migration and adaptation as these populations spread from Africa to other parts of the world. By analyzing mtDNA variations, researchers can reconstruct the paths taken by these ancestral groups, providing insights into human evolution and the genetic diversity present in contemporary populations.