So on FB today, I came across someone making this claim, " The natives from the artic to the southern most tip of south America. Can all be linked to the 8 families that crossed the land bridge from Asia to Alaska. Columbus is given credit for linking the "lost" human race. That had no other way of contacting the "known" peoples. Until Columbus made his voyage. It is true that Columbus brought diseases to the Americas. But he also brought syphilis back to Europe. ".
I've used my google fu to no avail finding any way to confirm or discredit this statement. I've never heard of this viewpoint of Columbus.
Follow-up question: On the contrary, I've seen it suggested that contact across the Bering Strait, between Siberian and Alaskan Yupik peoples, never ended, and that there was a(n obscure and indirect) link between pre-Columbian Europe and South America that continued through 1500. For example, this simulation of human genetic spread relies on the assumption that there were continuous occasional migrations across the Bering Strait for millennia.
Is this a more or less plausible theory than the idea that the Americas were completely isolated from Eurasia before 1492? I've struggled to find good information about this, and maybe it's better suited for /r/AskAnthropology.