The public has through 9/6/16 to weigh in on the proposed policy change. Assuming that the decision afterward is still to approve the new stance, it will go into effect about January, 2017.

This is a controversial issue. There is a lot of hope, on the glass is half-full side of the argument, that from such studies may come much needed new understandings about how to combat human diseases such as Alzheimer's and Parkinson's. In addition, there is the possibility that human organs (such as hearts, lungs, livers, pancreases, and kidneys) could be developed which might be transplanted into the bodies of people whose own organs are in terminal failure. Besides these opportunities, scientists would like to develop animals that have human sperm and eggs, to obtain fresh knowledge about Homo sapiens embryo development and the causes of infertility in our species.

The new creatures, known as chimeras, would in some senses, legally at least, not be thought of as human, so it would be considered OK to manipulate their embryonic forms to do such scientific inquiries and/or to develop organs for harvesting to benefit real people.

Pigman (image from TVtropes.org and Wiki)

DNA mixing is not always precise, so there is the potential that human cells might develop amid the non-human ones in the creatures' brains, with unforeseen consequences. Could these part-animal, part-human beings have intelligence the way we think of it? Might there in a few cases be enhancements, so beneficial traits of each part of the mix could be combined? Perhaps on occasion chimeras would be found to have, for example, both the subtleties of human emotions or consciousness and the heightened sensory capacities or muscular strength of feral pigs? Given that some of these creatures are expected to have human gametes, might a few of them be able to breed with humans?

If there is a slight possibility of such things, then in time they might become a reality. It is not necessarily just fictional that, as in the original Jurassic Park movie, "Life, uh, finds a way."

Likely those proposing the policy change would object that worst case ideas are too far-fetched to be taken seriously.

The anticipated new guidelines, for example, would have a prohibition on DNA mixing between people embryos and those of non-human primates, lest there result hybrid beings too close to us. Further, extra steps would be taken to assure no harmful repercussions from the development of human sperm and eggs or the blending of human and non-human brains. Certain lines of research would be required to pass through added layers of review before the OK would be given. Chimeras would, however, be acceptable that are mixes of human DNA with that of pigs, sheep, and cattle.

Those in the glass is half-empty camp may express concern for ethical dilemmas in the creation of new forms of life intended to be used for organ harvesting, in the use of human sperm and eggs for other than human to human reproduction, in the development of creatures that are more human than not inside the wombs of non-human animals, in the inadvertent breeding of chimeras with humans and resultant new mixed-species beings, in the use of partly human beings for medical research, and in the promotion of new kinds of consciousness and intelligence.

While researchers argue sufficient steps would certainly be taken to prevent such concerns from being warranted, others still doubt the efficacy of these lines of inquiry. Their own fears assuaged, many scientists are thrilled, though, with the chances for breakthrough medical advances that might soon be available. It would, indeed, be a fine thing if Alzheimer's and Parkinson's diseases might be greatly reduced or susceptible to practical treatments in another generation or two.

One wonders, if our scientists are eager to begin this type of experimentation once special precautions are in place, what researchers of other countries may be ready to do in our version of a "Brave New World." Among humans, we still have many who are treated shabbily when they are for whatever reasons regarded as "other," and hence lesser, than ourselves. Can we be certain more humane treatment will occur for those whom we create to serve our ends and whose usefulness is largely based on how much they are like us, yet not us?

Primary source: NIH Plans To Lift Ban On Research Funds For Part-Human, Part-Animal Embryos. Rob Stein in NPR; August 4, 2016.