Given The Bering Land Bridge theory, why is it that there were more Indians in South America rather than North America?

Question

If the Land Bridge or kelp highway theory holds, at first glance it would seem to make more sense that there would be more people in North America rather than South America but by the time of Columbus, it is estimated there were 100 million Indians in South America and only around 3 million Indians in North America. What would explain such a discrepancy? For example, is it possible a lot of North America was still covered in ice forcing more and more people to the South? Also, when I am referring to the kelp highway, I am referring to the idea that they used boats alongside the Bering ice bridge. I was watching a video where this was called the kelp highway because they could gain sustenance from all the kelp that grew along this ice coast. Are there other theories out there that might suggest people went directly to South America or another part of North America and migrated to South America? I am aware of the Solutreans hypothesis and of some other skull finds in Mexico City (Eva of Naharon) and Brazil (Luzia) but I don't know whether these are believed to be connected with the Siberian descendants. I do believe the Kennewick man was found to be so though.

Answer 1

There is currently no good way to estimate the Pre-Colombian populations of North or South America at any specific time. Scientists just don't know which continent had the larger population, and even if there were some way to find out, knowing which one had the larger population pre-colonization would not be particularly useful to science and would have very little to do with the manner in which humans migrated to the Americas thousands of years earlier. Whatever migration theory you believe, there certainly weren't millions of people who took the route.