It might sound like something out of science fiction, but combining human and animal DNA isn’t the fantasy of some far-flung future. It’s something that scientists have already done several times—and it’s forcing us to reckon with ethical questions we never thought we’d have to consider.

According to the scientists, the part-human animals they’ve created will do nothing but good. They’re a scientific breakthrough that’ll let us run medical experiments and procedures on something they consider less than human.

But we’ve yet to decide where the line between man and animal will be drawn. It’s still an open question: Are these creatures mutated animals—or the beginning of something more human?