I believe that the first outbreaks known to Europeans happened in the '70's, but the idea that it could never happened before since we hadn't noticed it yet is naive. But shutting up now anyway. Perhaps they do know from the dna that it couldn't have ever happened before we noticed it, but even if not, side issue. I just prefer that we get into the habit of saying "first known to us" instead of "first known" about stuff that happens outside of our narrow little culture.