Mutations accumulate at a slow enough rate so that we know that they are very, very similar to modern humans as 24000 years is a very short time for that; and t

Mutations accumulate at a slow enough rate so that we know that they are very, very similar to modern humans as 24000 years is a very short time for that; and the reasonable proxies for intelligence that can be measured archeologically i.e. brain volume are the same or even in their favor.