Iron Road: Not human.

"That's right. I never told Frank about the Graemlings. Did you ever hear the stories about gremlins the pilots tell? Little goblins that got onto planes and wrecked them?"

"But--"

"Well, it turns out the legend had some basis in fact. The Graemlings did exist, but they're gone now. A completely different race. Not human at all. The real native Nieberlanders, in fact. They haven't been seen for about a hundred, a hundred and fifty years. It would have been the year 1800 or so, about the end of the Holy Roman Empire. Which is the time the immigrants to Nieberland from Germany stopped coming in the other way. Incidentally. The legend has hung around for a while, and it went the rounds as a rumor among the pilots, but nobody living has actually seen one."