Human-animal hybrids have existed only in our imagination fueled by vivid mythological creatures, most popular being the mermaids and the centaurs. So when scientists showed an active interest in mixing human and animal genes, mainly to mass produce vital hormones like insulin, and drugs and organs suitable for organ transplantations, it was interpreted widely as an attempt to create monsters which could be half-human-half-animal. Thus the term Para-human became popular as an informal reference to "human-animal hybrids" and many started speculating creation of monsters.

Broadly speaking, human-animal hybrid experiments are aimed to better understand the function of human body by eliminating the restraints currently experienced by scientists. For instance, if mice could be created with human immune system, it could go a long way in the study of AIDS and in creating effective treatment.  

Human-animal hybrid also serves as an alternative for cloning and stem cell research, both with several legal restrictions.

Transhumanism, a movement which advocates the need to develop better humans (or posthumans) by means of eliminating aging and enhancing human's intellectual, physical, and psychological capacities, strongly support the ongoing researches to create human-animal hybrids.

The Academy of Medical Sciences which published a report in July, examining the use of "animals containing human material" (ACHM) in researches, explains the need to create human-animal hybrid which they term as ACHM.

According to the researchers, human-animal hybrids help "understand human bodily functions and human disease where cell or computer-based alternatives alone will not suffice, and it is morally or practically impossible to do the necessary studies in living people."

ACHMs also help "determine the role of a specific piece of human DNA, our genetic material, by seeing what effect it has in a living animal" and "to  test and develop methods of diagnosis, drugs and other treatments for human disease."

The ACHM research synopsis says animals can be genetically altered by "adding to it the human genes that you wish to study or by changing its genes so that they are the same as those in man."

Researchers also provide an alternative by which "you can create chimeras: animals formed either by mixing human and embryonic cells, or by implanting human material into an animal" by means of stem cells.

Answering ethical and regulatory questions:

The synopsis concentrates on three ethical and regulatory difficulties faced by Human-animal hybrid research.

The paper denies "likely" cross fertilization of humans and animals by means of fusing human eggs or sperms with animals' reproductive mechanism.

"Human reproductive tissues can be implanted in various places (such as under the skin) in the recipient animal rather than into its own reproductive system, so there is little possibility of fertilization." Nevertheless, if in case an "inadvertent" cross fertilization occurs, "it is very unlikely that the event would result in a viable embryo."

Researchers admits the possibility of "human appearance or behavioral traits" in ACHMs and express their concern about "blurring of these (physical looks and behavior) boundaries" and calls for national expert advice in proceeding with any ACHM research involving creation of what is being popularly called as "human-animal hybrid monsters."

They also answer the issue of introducing human memory to primates. If there is any uncertainty over "possible changes to an animal's brain function following a procedure, the work should proceed cautiously and incrementally, and should be subject to additional oversight by a national body of experts."