Because I got sick from it. We discover things about the world that have been true since before history. It doesn't mean I believe it has been isolated. There were okapi in the wild, before there were okapi in the zoos. Did the okapi only exist when it was captured and put into a zoo? If no okapi were in zoos, did that mean the okapi didn't exist? These were topical questions when the existence of the okapi was a controversy.