The signal does not indicate that the people carrying it are part-Australian or part-Melanesian in any direct sense.

It indicates that their ancestral history included a component that, somewhere in the deep past, shared common ancestry with the ancestral populations of Australasia more recently than expected under a simple model of human dispersal.

The explanation of this signal remains genuinely uncertain.

The most parsimonious current explanation — deep ancestral structure within the founding Native American population, reflecting the complex population history of northeastern Asia before the American dispersal — is consistent with the evidence but cannot be directly tested with the ancient genomes currently available.

Other explanations — an early coastal migration of a population related to Australasians, a distinct secondary migration through Beringia — are not definitively ruled out by the current evidence.