Moving the Goalposts on Hybrids

In recent years, biologists have been advocating the use of various human-animal constructs in their work. They seem to get what they want. In fact, they may now be getting more than they even asked for.

There are different kinds of entities at issue. Chimeras, in which cells from different species are mixed at the organismal level, are used for testing stem cells or, theoretically, producing organs for transplant. In contrast, hybrids mix the DNA of different species at the cellular level. These hybrids can be of the cytoplasmic variety, for which scientists have made a good case. In these, enucleated animal eggs would be used as the target for human nuclear transfer in cloning-based stem cell research as an alternative to scarce and problematic human eggs. 

Until now, it seemed that “true” hybrids, in which human sperm fertilizes an animal egg (or vice versa) were off the table. But recent maneuverings in the United Kingdom illustrates the research community’s insistence that nothing be taken off the table, regardless of actual need. It’s relevant not just for British policy, but also because that nation’s regulatory structure has been held up a model of oversight. Unfortunately, the British model, originally founded on the principle that “There must be some barriers that are not to be crossed, some fixed limits, beyond which people must not be allowed to go,” appears to be unable to say “no” to researchers’ demands.

The current setting is a multi-year process to update the key law regarding human genetic and reproductive technologies. For three years, the Government (i.e. the cabinet), Parliament, the Human Fertilisation and Embryology Authority (HFEA), and interest groups have been issuing reports and holding public consultations. The Government has been cold to hybrids, and Parliamentarycommitteesvocally supportive. In May, the Government conceded that cytoplasmic hybrids could be permitted, under license, but legalization of true hybrids would require an act by the Secretary of State for Health.

In media coverage, researchers reassured the public that the cytoplasmic hybrids would be 99.9% human and only 0.1% nonhuman. Yet at the same time, the research community was pushing for the normalization of true hybrids - despite the fact that no one had any particular reason to create them. A survey [PDF] of scientific groups by the HFEA stated that, “The general view of the organisations we consulted, and the view expressed in the Academy of Medical Sciences' recent report on inter-species embryos, was that currently there is no reason why scientists would want to create human transgenic embryos, true hybrids or human chimera embryos.” And its Scientific and Clinical Advances Group [PDF], containing over a dozen biomedical researchers, concluded that, “that there is no scientific case for true interspecies hybrids.”

On top of that, public opinion ranges from slightly to significantly opposed. In a HFEA poll [PDF], 36% of respondents agreed that true hybrids should be allowed, while 47% disagreed. In its focus groups [PDF], only 9% agreed, while 73% disagreed.

Notwithstanding the absence of both scientific need and public support, research groups countered that a law couldn’t, and shouldn't, distinguish between cytoplasmic and true hybrids. For example, the Academy of Medical Sciences concluded that "The reasons for banning the creation of hybrid embryos for in vitro experimental use, while permitting research involving other types of human embryo incorporating animal material, are not clear to us…." And a representative of the British Medical Association testified, "We have not had any justification for the [Government proposed] exclusion of true hybrids, and it would be interesting to know if there is a reason, but we would say that it should be treated in the same way as the three forms of inter-species embryos that will be allowed and we would rather not say in the legislation that there is one group of hybrids that would not be allowed because we do not believe it could be readily revisited and it might become an essential." Other true hybrid advocates similarly noted that if the concern among the public was crossing the species barrier, then permitting cytoplasmic hybrids had already done so.

Thus, if cytoplasmic and "true" hybrids are legally and morally inseparable, and its agreed that the former should be permitted, thus the latter must be as well. It seems an effective strategy to prevent any prohibitions on research activities, regardless of their actual need, is to convince the public that you are not going to cross a line, and then claim that the line can't really be drawn.