A person’s mitochondrial DNA comes from their mother, who got it from her mother, who got it from her mother, all the way back through time.

Because mitochondrial DNA does not undergo the mixing and recombination that characterizes the rest of the genome during reproduction, it retains the accumulated mutations of the maternal lineage relatively cleanly.

Those mutations accumulate at a roughly predictable rate, and the specific pattern of mutations in a person’s mitochondrial DNA places them within a haplogroup — a cluster of related lineages that share a common ancestral sequence.

The major mitochondrial haplogroups found in Native American populations — typically designated A, B, C, D, and X, with various subgroups including D1 — all derive from Asian populations, consistent with an ancestral migration from northeastern Asia into the Americas via the Bering land bridge.