"The thing is, the "scientists" back at the School had been playing with risky stuff, combining human and nonhuman DNA. Basically, the spliced genes started to unravel after a while, and the organisms tended to, well, self-destruct. The flock and I had seen it happen a million times: The rabbit-dog combo had been such bad news. Same with the sheep-macaque monkey splice. The mouse-cat experiment had produced a huge, hostile mouse with great balance and an inability to digest either"