Some human beings will never be human. LOL.
...
A fertilized egg...  

During the Holocaust, Nazis referred to Jews as rats. Hutus involved in the Rwanda genocide called Tutsis cockroaches. Slave owners throughout history considered slaves subhuman animals. In Less Than Human, David Livingstone Smith argues that it's important to define and describe dehumanization, because it's what opens the door for cruelty and genocide.
...
This is just the latest iteration in a pattern that has unfolded time and again over the course of history. In ancient Chinese, Egyptian and Mesopotamian literature, Smith found repeated references to enemies as subhuman creatures. But it's not as simple as a comparison. "When people dehumanize others, they actually conceive of them as subhuman creatures," says Smith. Only then can the process "liberate aggression and exclude the target of aggression from the moral community."

When the Nazis described Jews as Untermenschen, or subhumans, they didn't mean it metaphorically, says Smith. "They didn't mean they were like subhumans. They meant they were literally subhuman."
...
A rough answer isn't hard to come by. Thinking sets the agenda for action, and thinking of humans as less than human paves the way for atrocity.