Why We Need to Be More Accepting of 'Humanized' Lab Animals

Many, including President Bush, have called for an end to human-animal hybrids, but these creatures are critical to medical research


The creation of human-animal combos has people across the political spectrum worried. Over the summer, a survey by the the U.K. Academy of Medical Sciences found "unease about work that could introduce human traits into animals' brains, reproduction, or appearance," according to Nature News.

One conclusion of the U.K. scientists' report: Strictly verboten is putting human brain cells into higher primates that could make them smarter. A committee of the National Academy of Sciences that I co-chaired in 2005 similarly warned against putting neural stem cells from a human source into a primate without due consideration.

The point is not that the scientists themselves think there's something to worry about. The likelihood that anything "human" would survive in the consciousness of primates with human brain cells is remote. Rather, the scientific establishment is worried about what in Washington is called "optics": How "humanized" creatures might cause a backlash against important biology. Another item in the Daily Telegraph listed cross-breeding a human and a chimpanzee as one of a handful of scientifically valuable but ethically unacceptable experiments.

Still, we obviously find the very idea creepily fascinating. A new Science channel series called "Dark Matter" debuts this fall with the true story of a Soviet scientist's attempt to create a human-chimpanzee hybrid in the 1920s. The Planet of the Apes series has included provocative suggestions of inter-species crushes.

The trouble with all this is that important medical research does involve putting some human cells into animals. These lab models, usually rodents, are called "chimera," after a creature in Greek mythology. Although these chimera are not the results of cross-breeding, some chimera are hybrids, like the geep, which is a cross of sheep and goats.

Happily, the U.K. survey also found that non-scientists' attitudes shifted when people understood the justification for chimera-based research. Using chimera, geneticists are learning how a single gene operates in a complex system. Chimera are being used to build a foundation in stem cell regenerative science, the study of the ability of stem cells to hone and replace damaged tissue. For instance, in models of neurological disorders, human-primate and human-rat brain chimera have been used to test the feasibility of future neural stem cell treatment of Parkinson's disease and stroke. In addition to their role as model organisms, human-animal chimera are a fundamental part of understanding the basic biology of cellular development and viral disease. Human-mouse bone marrow transplants have been performed since the 1980s and have been part of studies of AIDS and leukemia.

The British are actually behind the curve when it comes to worrying over mixing species. In his 2006 State of the Union address, President George W. Bush asked congress "to pass legislation to prohibit the most egregious abuses of medical research," including "creating human-animal hybrids," the latter being a special sort of chimera that involves the fusion of genes from two species. Then-Senator Sam Brownback of Kansas had crusaded for years against human-nonhuman organisms. The senator's latest attempt, the Human-Animal Hybrid Prohibition Act of 2009, would prohibit the creation of a whole range of human-nonhuman organisms. The draft bill included findings that human-nonhuman hybrids are "grossly unethical" because they "blur the line between human and animal, male and female, parent and child, and one individual and another individual." Brownback also emphasizes that human-nonhuman hybrids are a threat to human dignity and to "the integrity of the human species."

Although the Brownback bill never got out of committee, at the state level there has been some success on this track. In 2009, Louisiana Governor Bobby Jindal signed into law a bill that was similar to Brownback's, prohibiting human-nonhuman hybrids.

Violation of the law is a felony. A bill passed by the Ohio senate lists eight kinds of "human-animal hybrids" that would be outlawed. A similar bill is up for consideration in the Arizona state legislature. Perhaps Governor Brownback will put forward a similar bill in Kansas.

As I explain in my new book, The Body Politic: The Battle Over Science in Americasimmering worries about chimera and hybrids, along with debates about stem cells and cloning, are part of an emerging era of biopolitics. Unlike traditional biology that mainly observed and categorized, the new experimental biology threatens to undermine species boundaries, calling into question what it means to be human, our place in the natural order.

Geneticists at the Max Planck Institute have pretty much proven that our ancestors mated with Neanderthals about 40,000 years ago. Perhaps our collective anxiety about mixing human cells with other creatures is a bit of highly conserved species memory about some really bad dates.

Image: A chimeric mouse/Wikimedia Commons.