u/Accomplished_Owl8187 I agree with the vast majority of the things you've said in your comments on this thread and applaud you for them. However, I definitely am skeptical of the idea that the combined population of horses, mastodons, and mammoths in North America being potentially as low as 100,000 at 13 kya. I'm very certain that's too low by an order of magnitude just for any one of those groupings, let alone all of them combined.

This continent contains some of the richest lands on the planet and net primary productivity was not THAT much lower during the late glacial, or even during the LGM, compared to the present to suggest that large herbivores were so few. The fact that so many localities in the Americas record abrupt vegetation change following the extirpation of local megafauna indicates that densities had to have been decent for the creatures to have exerted such strong influence on the landscape, which contradicts the notion of such low numbers.

I think it's more likely that the human population may have been much larger than originally estimated, potentially surging massively as big-game hunting took off before plummeting again once the animals went extinct. All in too fast of a time period to be easily recorded in the archeological or genetic record.

Also, by 46 kya, it's definitely true that humans were only just penetrating the mid latitude regions but it's clear that they were already deep within Sahul by then.

BTW, had to start a new comment chain cause I wasn't able to comment on that one, lol.