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Why did Genographic Project researchers study Y chromosomes and mitochondrial DNA?

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Large illustrated genealogical tree with detailed branches and leaves, featuring family names and a central family crest, representing the Lippincott family lineage. — Genealogy Genealogical tree of the Richard and Abigail Lippincott family in America, constructed and published by Charles Lippincott, 1880.

Researchers for the Genographic Project studied Y chromosomes and mitochondrial DNA (mtDNA) because these specific genetic components allow scientists to trace ancestral lineages back many generations.1

The Y chromosome is used to trace paternal lineages because it is passed from father to son and contains regions that do not undergo recombination, which is the mixing of genetic material that typically occurs during cell division. Similarly, mtDNA is inherited maternally by both sexes, allowing researchers to trace maternal lineages.12

Because these segments of DNA are largely nonrecombinant, they accumulate mutations over time that serve as genetic markers. By analyzing these markers, researchers can identify the geographical location and migration patterns of ancestral populations. When combined with archaeological and linguistic data, these analyses help scientists understand how Homo sapiens migrated out of Africa and dispersed across the globe.12