The big animals consumed little peace and animal loving people - wiping out prehistoric traces of liberals. They must have left one somewhere, because they reared their ugly heads again.
They must have left two. One couldn't have mated. (Unless she lied through her teeth like my first wife.)
That would be the Treadwell Culture, named after a recent individual (Timothy Treadwell) who thought inviting bears to dinner would not result in the host being the main course.