Meller, the painter in Greene tribe kills one of the guards to help Roy and Marapper escape. Later we learn that Meller is really an Intruder. And Intruders and Giants are forbidden to kill any of the inhabitants. Meller basically broke Earth's law. We never get to know whether he was somehow punished or not.
The ship's inhabitants live 4 times faster than normal humans. That means they're biologically mature and thus ready to mate and bear children before turning five years. By that time Earth kids are still in kindergarten.
