Human-Animal Transgenesis and Chimeras Might Be an Expression of Our Humanity

Jason Scott Robert and Françoise Baylis (2003) identify important scientific advances that have massive social implications. I have written on the ethical implications of these advances elsewhere (Savulescu 2003). Here I can sketch only a framework for evaluating these advances. In what follows, I will use "animal" to refer to "nonhuman animal."

Possibilities

Robert and Baylis are right that there are scientific experiments that introduce human genes and embryonic stem cells into animals to create animal-human chimeras.

But it is now also possible to introduce animal genes into human beings by germ-line genetic manipulation. It is also possible to introduce totipotent or pluripotent cells from animals to make more full-blown human-animal chimeras. For example, it would be a straightforward technical matter to fuse a human embryo and a chimp embryo. The resulting human-chimp chimera might be viable. Any resulting being would be a blend of the properties of each. While the resulting chimera might not look like one of the apes from the film Planet of the Apes (though it might), it would look and be very different than a human being or an ape.

What might be reasons for creating transgenic human beings and full-blown human-animal chimeras? Some of these reasons would be questionable: commercial exploitation of "freaks"; artistic motivation (which led to the creation of the fluorescent rabbit "Alba" by French scientists); or curiosity, just to see what it is like, as Dawkins memorably said in connection with cloning. But there might be good reasons to radically alter human beings.

Medical Purposes

At a basic level, human-animal chimeras offer the opportunity to study cellular maturation and migration, as well as oncogenesis.

Chimeras might have unique properties as a source of embryonic stem cells. Robert and Baylis point out that human-cow (and indeed human-pig) chimeras have already been produced as a source of stem cells.

Or consider the case of the human immunodeficiency virus (HIV). HIV is rampant. At the present time there is no cure or vaccine. Imagine that scientists discover that some species are resistant to HIV infection and that resistance is genetically encoded. Imagine that it becomes possible to introduce these gene sequences into the human genome in order to confer resistance to HIV. While this is speculative, it is not absurd.

It would also be possible to create very weak chimeras. It is theoretically possible that a single or a few animal embryonic cells among, say, 16 human cells would be enough to confer resistance to diseases by producing certain protein products or having some kind of immunological effect. This would be a weak chimera that is predominantly human.

More radically, it is theoretically possible to combine a number of pluripotent or totipotent stem cells from a number of different animal embryos into the human embryo. Or, one might introduce animal genes from several different species into a human embryo. The resulting entity might have unique and desirable immunological properties or properties that render it more resistant to disease.

Delay Aging or Prolong Human Life

For some time we have been aware that the phenomena of aging in human beings is related to the degradation of telomeres, the regions on the end of our chromosomes (Rudolph et al. 1999). Suppose that we were to find that animals that have a significantly longer lifespan than human beings, such as turtles, contained genetic sequences that reduced the rate of telomere degradation. It might then be possible to transfer these sequences into the human genome, radically prolonging life or compressing aging. This would be enhancement for radically longer life or less aging, but it seems good, at least from the prudential point of view.

Enhance Human Capabilities

There is some evidence that elephants have highly developed social memory and that this leads to greater reproductive success (McComb et al. 2001). Transfer of the relevant genes...