There was a good column in the July 16 Boston Globe by Vivek Ramashwamya, a biology student, urging restraint by scientists in the creation of human/animal chimeras. He writes:
If the creation of these new organisms bothers us as a society, we must ask ourselves why. We cannot merely dismiss human-animal chimeras as “unnatural,” or else we would have just as easily dismissed recombinant DNA technology or any other scientific improvement upon nature. Nor can we merely accept that creating chimeras is ethical because of the potential medical advances; to do so begs the larger question of when ethical considerations should trump scientific inquiry... [P]olicymakers should use the following simple principle as a guide: one should treat a recipient of transferred humanity with the same level of respect as an organism with inborn humanity — in other words, a human being. Even if an organism does not appear to be fully human in biological terms, it nonetheless deserves the moral value of a human being, as long as it possesses the qualities that our society has deemed worthy of human respect.That would be a good start. Scientists should agree to restrain themselves in making these transgenic and chimeric animals so as to give society the time to hash all of this out (with their input, to be sure). The goal should be to craft binding international regulations that would permit the areas of inquiry that pose “no serious ethical risk,” in Ramashwamya’s words, while also ensuring that scientists don’t manufacture quasi-humans.There is no societal consensus on what qualities merit such respect. But nearly everyone agrees that the capacities for language, consciousness, or rationality are probably among them. If a human-animal chimera (such as a monkey with a human-like brain) comes to possess any of these qualities, then it would be morally objectionable to create that organism. Meanwhile, certain chimeras, such as a mouse with human skin grafts or human muscle cells, pose no serious ethical risk.
Don’t hold your breath for “the scientists” to embrace this eminently reasonable approach. Too many leaders of the Science Establishment worship at the church of scientism. And scientism sees science as an end rather than a mean and disdains most restraint as an infringement on the fundamental (and some say, constitutional) right to engage in scientific research. Add to this mix public intellectuals—such as the transhumanist leader James Hughes
(Citizen Cyborg)—who fervently yearn for the creation of such creatures as a way of knocking humans off of the pedestal of exceptionalism. But as Leon Kass wrote (I think), it would be a terribly cruelty to manufacture a human/animal chimera possessing sufficient levels of human reason to know that it was the artifact of an unethical and inexcusably selfish scientific experiment. 
