There is currently much debate over the ethics of chimeras — organisms that are partially one species and partially another. This debate is especially heated when humans are one of the species involved. Nature has published an editorial on the controversy. I don’t intend to comment on the position of the editorial, but rather on the sloppy use of language by the unattributed author.

I don’t know enough about the research and clinical applications of chimeras involving humans to make any claims about the ethics of such creations, but I do know enough about biology to get all hot under the collar when I see a sentence like this:

Under what circumstances should the fusion of cells of animals and humans be permitted?

Or this:

The new proposals provide a well-reasoned and permissive approach to the contentious issue of the nuclear transfer of human nuclei to a human donor egg for the purposes of therapeutic cloning, and also propose that other research combining animal and human materials should be subject to more stringent licensing procedures.

And this:

The document recognizes that human-animal fusion products have been widely used in biomedical research for many years.

Or how about this:

In the United States, the National Institutes of Health does not fund research involving the transplantation of human embryonic stem cells into animal embryos. In Canada, this funding restriction extends to the transplantation of human tissue-specific (or ‘adult’) stem cells to animal embryos.

Notice the trend? They all perpetuate the false dichotomy between humans and animals. Once again, I could care less — at least for the sake of this blog — about whether chimeras involving humans are ethical. What bothers me is the concept that these are human/animal chimeras.

It’s not like the author can’t get it right. Here’s an example of the proper terminology:

In 2005, the US National Academy of Sciences stated its opposition to research in which human embryonic stem cells are introduced into non-human primate blastocysts.

It’s “humans and non-humans” not “humans and animals”. And here’s another example of proper terminology, this time when we’re talking specifically about primates:

Another important line of investigation is the engraftment of human stem cells into non-human primate models.

Beautifully done. Because humans are both animals and primates, it makes no sense to write about “human/animal chimeras” or “human/primate chimeras”. I wish the author of the editorial had taken note of the terminology from the one cited article:

Human/nonhuman stem cell chimeras will be increasingly applied to study human cells in developing nonhuman animals. Such experiments raise a number of issues that may create further controversy in the stem cell field. Here we outline the scientific value and ethical ramifications of such studies, and suggest how such experiments may be conducted ethically.

The cited Nature Medicine article executes a nearly flawless use of the human/nonhuman terminology. If only the Nature editorial hadn’t been so sloppy.

And, as an added bonus, I present a passage displaying the chimeric property of half proper terminology and half crappy terminology:

At present, such guidelines are reasonable but do not consider several promising and arguably necessary avenues of research that combine human cells or cellular components with other species. These include combining the genetic material of humans and other species, the prenatal combination of cells from different individuals (animal to human, human to animal, or human to human), or grafting tissue from humans to animals.

To recap: “humans and nonhumans” or “humans and other species” is a-ok. Just don’t write about humans and animals.