ABSTRACT
The history of chimeras goes back to ancient Greek mythology. Originally, a chimera referred to a mythical animal with the head of a lion, the body of a goat, and the tail of a serpent. In the current world of scientific research, chimeras are organisms composed of cells or genes obtained from two or more different species. Human–animal chimeras can be generated by either transplanting human stem cells into animal fetuses or human genes into the genome of animal fetuses. The first modern interspecies chimeras were engineered in the 1980s with little ethical debate. However, in the last decade, new and challenging bioethical dilemmas regarding human–animal chimeras have emerged, creating considerable debate on the appropriateness of such research.
