Sublime's book states that there is a "third species" on Earth called "Homo perfectus" or "the Recycled Man". The so-called "Third Species" is composed of normal humans who believe it is their right to use mutants and mutant parts to give themselves "chosen mutant" abilities. They do this by capturing mutants and harvesting their organs or other body parts to use either as grafts and implants (such as eyes with x-ray vision or blood transfusions that grant electrical abilities) or as tools (such as Martha the Mutant Brain). Like normal grafts and implants, the mutant organs do not always take, and some U-Men die as a result of the process, such as U-Man Bob Smitt, who died of blood poisoning when his mutant lung grafts rotted inside him. U-Men view the failure of a graft to take as a measure of an individual's "purity" and deservedness to be one of the Third Species.