alt Hacker NewsYes, I’m afraid that you are still misunderstanding the research. Your linked article speaks about gene flow associated with the movement of pre-Proto-Germanic speakers to Scandinavia, but later Proto-Germanic formed in southern Scandinavia according to the longstanding consensus. This is clearly spelled out in the abstract: “Following the disintegration of Proto-Germanic, we find by 1650 BP a southward push from Southern Scandinavia.”
There’s no new theory here at all, just some nice archaeogenetic evidence to support a quite traditional view. FWIW, I work in a closely related field and am constantly reading Germanic–Finnic and Baltic–Finnic contact literature, and I can assure you this is old-hat stuff.
Do you think I'm misunderstanding something other than that I'm not drawing the same distinction between proto-Germanic and "paleo-Germanic" that that paper appeals to?
You've quoted something that says after proto-Germanic had diversified, daughter lineages left southern Scandinavia to establish themselves elsewhere in the world.
But I pointed out a completely different idea in the paper, that before proto-Germanic diversified, about 2000 years before the time you mention, its speakers arrived in Scandinavia from "the northeast coast of the Baltic".