The specific route — if any separate migration occurred — by which Australasian-related ancestry reached South America.

Why the signal is found in some South American populations and not others.

How much of the geographic variability in the signal reflects the original settlement history versus subsequent population dynamics.

Why it matters: The Population Y story is not merely an academic puzzle about ancient DNA statistics.

It touches on fundamental questions about the deep history of human populations — about how humanity spread across the planet, about the ancestral structure of the populations that gave rise to the diverse array of human groups alive today, and about the specific history of how the Americas came to be inhabited.

Getting the story right — including being honest about what is and is not known — is important both for the scientific record and for the communities whose ancestors’ DNA is being studied.