If you'd bother to use the internet to seek out information, you wouldn't even ask these rhetorical questions about non-issues.
And yes, scientists aren't certain about every aspect of mammoths. Admitting doubt keeps you out of more trouble than people (like you) who think you as an individual know more than the collective brains of countless scientists, and are so easily proven totally wrong!
Hmm. Not one respectable university that I've ever heard of has ever rejected science. But you know better than all those academics, doncha?