Early in the story, when Melanie and the other children are simply test subjects, characters routinely refer to them as “nonliving,” “not human,” or simply as “it.” These are convenient idioms that help to justify the children’s cruel treatment. Indeed, even as Dr. Caldwell cuts open the skull and removes the brain of a squirming child, she chastises herself for offering words of comfort. She argues repeatedly that the children are nothing more than ambulatory husks devoid of anything that might classify them as human. However, the very fact that she is studying them to discern what makes them different from the average hungry suggests that she is fully aware of the difference, and until she knows that they’re not fully human, experimenting on them as she does constitutes a serious ethical violation.

Like speculative fiction more broadly, science fiction offers a convenient vehicle for exploring what constitutes humanity, sidestepping real-world questions of how we treat people (and perhaps even animals) who aren't like us for more fantastical scenarios. For example, the Sci-Fi Channel’s reboot of Battlestar Galactica (2004-2007) turns largely on the issue of whether robots who look and act human are less human that their flesh-and-blood counterparts.