But it was only the last ice age that man kind started to spread around the world.
I will give you another example, Australia
The Mega-Fauna there went extinct 50,000 years ago.
Why did they go extinct there 50,000 years ago instead of the 5,000- 10,000 here in North America?
Simple because that’s when man showed up there.
Same with The Pacific Islands 30,000 years ago, Madagascar 2000 years ago, New Zealand 1500 years ago.
When ever ancient man showed up, the Mega Fauna went extinct.
The other way around ~ every where the mega fauna went extent humans were able to proliferate in large numbers.