At one time it was believed that the ancient Siberians, who crossed the land bridge across the Bering Strait connecting modern-day Russia and Alaska, were the only ancestors of Native Americans.
Recent research since the late 2000s has indicated that more diverse sources from Asia may be linked to a single ancient lineage responsible for the founding populations across the Americas, including Bolivia, Brazil, Chile, Ecuador, Mexico and California.
Known as D4h, this lineage is found in mitochondrial DNA, which is inherited only from mothers and is used to trace maternal lineage.
The team from the Kunming Institute of Zoology began a ten-year search for D4h, searching 100,000 modern and 15,000 ancient DNA samples across Eurasia, eventually landing on 216 contemporary and 39 ancient individuals that came from the ancient lineage.