There are reasons why we have “ewww” responses. They are not simply products of arcane didacticism. It may be your body, consciously or subconsciously, actually warning you about something. :)

The hybridization of humans and animals proposed by British scientists has a high “ewww” factor for me. Perhaps some of it comes from the multiple prohibitions in the Pentateuch against human-animal sexual relations, but the image of cells under a microscope is so visually distant from the bulk methods of creation that I can see how a scientist could favor hybridization without supporting the other.

Human-animal hybrid embryo study still has its own sets of “ewww,” though.

The first (in no particular order) problem I see would be the rejection factor. Suppose a treatment did come out of this. Would the animal proteins be rejected by humans? Would immune systems have to be compromised to allow such treatments to work, at the great risk of unmitigated infections?

The embryos would supposedly be destroyed 14 days after creation, but what if one doesn’t? Does the hybrid get rights? Suppose a scientist lets an embryo live long enough (assuming it doesn’t self-terminate) to an age where it can make choices about what it’s doing? Does it get human rights or animal?

I do subscribe to “life begins at conception.” When these embryos are destroyed, is it murder, as with a human, or animal cruelty? Perhaps it’s both — someone notify the SPCA. If we’re not going to respect humankind, at least save the animals. :P

There are likely very good and fundamental reasons why species are distinct and why we need genetic integrity. Sure, we have our mules, and more exotically, ligers, beefalo, and other hybrid animals. We have another “ewww” factor because we humans are unique. Whether we are demoting humans to animal or promoting animals to human, there is an ethical line crossed for all but the most extreme animal rights activists. This kind of research serves more to blur that line than to provide any cures.