If MA-1 had shown strong East Asian affinity, the result could have been accommodated within existing frameworks.

The absence of that affinity, combined with the strong Native American affinity, required a new framework.

The comparison with specific ancient genomes was also informative.

By 2014, a small number of ancient genomes from Upper Paleolithic Europe had been sequenced, representing the people who lived in western Eurasia before the major population transformations of the Neolithic period.

MA-1 showed affinities to some of these ancient Europeans that were not seen in modern western Eurasian populations, consistent with the interpretation that MA-1 represented an ancient population related to both the pre-Neolithic western Eurasians and to the ancient Siberians who contributed to Native American ancestry.

The statistical analyses supporting these conclusions are technically demanding — they involve tests of ancestry that go by names like f-statistics, D-statistics, and ADMIXTURE analysis — and the details of those methods are not easily summarized in non-technical language.