What the paper could not do — what no paper can do with limited data — was definitively resolve the question of which model was correct.

The subsequent work — the 2018 ancient genome studies, the expanding datasets of the 2020s, the ongoing methodological refinements — has not dramatically changed the fundamental finding.

The Population Y signal is still there, in the same general geographic distribution, at roughly the same intensity.

What has changed is the understanding of what that signal might mean, as additional data has tested and refined the competing models.

This pattern — a finding that generates multiple competing models, followed by progressive accumulation of evidence that constrains but does not yet definitively eliminate any of the models — is typical of how science works when confronting genuinely complex historical questions.