easy · GMAT Verbal

Passage: Mitochondrial DNA (mtDNA) is often used by geneticists to trace maternal lineage because it is inherited almost exclusively from the mother. Unlike nuclear DNA, which undergoes recombination during the formation of sperm and egg cells, mtDNA remains largely unchanged from generation to generation. Small mutations do occur over long periods, acting as a 'molecular clock' that researchers use to estimate the timing of human migrations. By comparing mtDNA sequences from different populations, scientists can construct a phylogenetic tree that maps how modern humans dispersed across the globe. Some critics argue that this method oversimplifies human history by ignoring paternal contributions and the influence of natural selection on specific mitochondrial genes. However, when combined with archaeological data, mtDNA analysis remains a cornerstone of paleogenetics. The author's attitude toward the use of mtDNA in genetic research can best be described as:

1. Concerned that mtDNA analysis is becoming obsolete due to nuclear DNA studies.
2. Certain that mtDNA is the only reliable way to map human migration.
3. Deeply skeptical of the accuracy of the molecular clock model.
4. Appreciative of its utility while acknowledging its limitations.
5. Entirely dismissive of criticisms regarding paternal inheritance.

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