Experiments with inserting human genes into animals have, among other astonishing results, produced mice whose brains are 1% human. Here’s an article discussing some research projects that have produced human-nonhuman chimeras: National Geographic The most crucial question about these lab animals, as mentioned in the article, is “When do they become human?” If some future experimental hybrid contains enough human DNA to cross that threshold, what rights would it have? I view efforts to grow human-compatible tissues in nonhuman creatures (if they’re treated decently) as an exciting advance toward solving the transplant organ problem. How would that application be different, in principle, from extracting insulin from the pancreases of animals? Other applications of this emerging technology look more problematic. However, I don’t agree with the person quoted as saying any such hybridization “diminishes human dignity.” Much less a different article I read recently, which characterized any mixing of human-animal DNA as an abomination on the same level as breeding viable human-ape babies. Imagine mice genetically engineered to produce human sperm cells and ova. Nobody is attempting this bizarre project now, but something similar has been done with mice for pigs and goats: National Geographic Someday we might actually face the ethical and social problems of intelligent, humanoid animals living among us like the Underpeople of Cordwainer Smith’s classic stories. Marg...