A maternal lineage is one part of ancestry

Mitochondrial DNA is particularly useful for studying maternal descent. Research comparing domestic sheep with Asiatic mouflon, urial and argali examined the broad geographic origins of sheep maternal lineages across Anatolia and the Zagros. This is a different question from asking which present-day breed has a particular fleece or horn shape. Maternal evidence follows one inheritance pathway; nuclear DNA combines ancestry contributed through both parents.

Keeping these pathways distinct prevents overinterpretation. Two sheep can share a maternal lineage while differing substantially across the rest of their genomes. Conversely, different maternal lineages can occur within a domestic population that people manage as a single breed. Species ancestry, breed formation and a flock’s recent pedigree occupy different timescales. Archaeology, maternal DNA and genome-wide comparisons can reinforce one another, but none should be treated as a substitute for all the others.