Chimeras: Beyond Our Moral Depth?

The Physicians Committee

Beyond Animal Research

By Jonathan Balcombe, Ph.D.
August 2005

Chimeras: Beyond Our Moral Depth?

The chimeras I learned about as a biology student—obscure, strange-looking fishes of the ocean depths—are not the same as the ones now at the center of a debate in medical ethics. These chimeras are made by man, not by nature. As stem cell technology marches ahead, science now has the means to create creatures that blur the line between humans and other animals. The specter of a half-chimp/half-man or a mouse with a human brain is no longer the stuff of science fiction.

The allure, from the biomedical perspective, is the hope that such chimeras will provide a “hugely useful” tool in biomedical research (Shreeve 2005). That’s why new guidelines for research issued in April 2005 by the U.S. National Academy of Sciences concluded, in a special section titled “Interspecies Mixing,” that there were valid reasons for creating chimeras.

The moral minefield, as expressed by those closest to the debate, revolves around the sinister potential for the creation of a human-like beast trapped inside an animal’s body. There’s little chance of this happening when chimeras are created by inoculating human cells into an adult animal, but the risk is considered real if those cells were transplanted into a fetus.

And there are other ways that “humanized” chimeras might be derived. Irving Weissman at Stanford University (and StemCells Inc.) is trying to create a strain of mouse that loses its own brain cells just before birth. By transplanting human neuronal stem cells into the brains of these mice, scientists could create a mouse with a brain made almost entirely of human brain cells (Shreeve 2005).

Clearly, moral restraint is called for. Yet more often than not, concerns are expressed only with regard to potential human suffering. Science isn’t likely to abide the production of humanized chimeras, but what about the animals, who stand to lose so much more in the chimera stakes? Modern studies demonstrate that they, too, have thoughts, feelings, and experiences.

Animals believe, play, plan, anticipate, deceive, remember, and create tools (Griffin & Speck 2004). They feel a broad range of emotions ranging from joy and excitement to frustration and despair (Panksepp 2005) and they’re attracted to the same environmental rewards (e.g., palatable food, social and sexual contact) as we are (Balcombe in press).

Today, animals in laboratories routinely endure deplorably confined, impoverished and stressful conditions (Balcombe et al. 2004) and are subjected to experiments rarely in their own interests. Until these conditions are improved and the animals are given a decent quality of life, chimeras ought to be left where they are—swimming in the ocean depths.

Jonathan Balcombe, Ph.D., is a PCRM research consultant with a background in ethology. He is the author of The Use of Animals in Higher Education, as well as many scientific papers on humane life science education and animal behavior. His recent scientific review showing that animal experiments are more stressful than previously understood was published in Contemporary Topics in Laboratory Animal Science.

Balcombe JP. in press. Pleasurable Kingdom: Animals and the Nature of Feeling Good. London: Macmillan.
Balcombe JP, Barnard N, Sandusky C. 2004 Laboratory routines cause animal stress. Contemporary Topics in Laboratory Animal Science. 43(6):42-51.
Griffin DR, Speck GB. 2004. New evidence of animal consciousness. Animal Cognition. 7:5-18.
Panksepp J. 2005. Affective consciousness: Core emotional feelings in animals and humans. Consciousness and Cognition. 14:30-80.
Shreeve J. 2005. I, chimera. New Scientist. 186:39-43. June 25.