I looked into the North American mammoth thing, wondering how we know that mammoths were in Alaska up until 5600 B.C. Turns out it's not from fossil evidence--it's from DNA sampling of permafrost. Ergo, if there were no permafrost, we wouldn't know the mammoths existed. (Actually, if we had missed that one core, we wouldn't know mammoths existed.)
Again, the point here is that it's really hard to know ancient history, and there are a lot of true things that really happened which science will never know anything about.
If I esteem mankind to be in error, shall I bear them down? No. I will lift them up, and in their own way too, if I cannot persuade them my way is better; and I will not seek to compel any man to believe as I do, only by the force of reasoning, for truth will cut its own way.
"Thou shalt love thy wife with all thy heart, and shalt cleave unto her and none else."