Chimeras: Medical Cure or Threat to Humanity?

National Public Radio (May 18, 2016): In Search for Cures, Scientists Create Embryos That Are Both Animal and Human, by Rob Stein:

Does creating animal-human hybrids--also known as chimeras--damage humanity?  Some bioethicists think so.  They are responding to developing technology that would perfect the manufacture of embryos that are part human and part animal.  The hope is that these embryos could be used to study human diseases and to grow human organs that could be used for transplants.  One technique is to remove genes from animal embryos that create certain organs and to fill the void with induced human pluripotent stem cells in the hope that they will fill it by creating the corresponding human organ.  If the patient needing the transplant donated the stem cells, her body would be less likely to reject the new organ.    

The National Institutes of Health has decided not to fund this research until the ethical issues are resolved.  These include the ethics of conducting experiments on animals and the uncertainty of what injecting human cells into animals might do.  One of the fears is that human intelligence might appear in animals or the embryo could develop into a creature that is half-human.