The most likely explanation for this signal, based on current evidence, involves the deep ancestral structure of the founding Native American population — the possibility that the population that crossed Beringia into the Americas contained lineages with different proportions of ancestry from different ancient Asian populations, including populations related to the ancestral southern-route dispersers that gave rise to Australasians.

This internal diversity, distributed differentially across the Americas as the founding population dispersed, would produce the observed pattern of excess allele sharing without requiring any migration from Australia to the Americas.

This explanation has not been definitively confirmed.

It requires ancient genetic data from Beringia and northeastern Asia at the relevant time period — data that is not yet available.

Other explanations remain possible, including models involving a separate coastal migration by a population related to Australasians.

These alternative models face significant challenges in explaining why the signal is not found in North American populations if the migration came through Beringia, but they cannot be entirely ruled out on current evidence.