Human Enough? 13 September, 2007

The genetic chimeras and human-animal hybrids whose creation in the laboratory was recently approved by the Human Fertilization and Embryology Authority in Britain (claiming that the public is now ‘at ease’ with the idea provided it is done in the aid of medical research), are not quite the Chimaera imagined by Homer and Hesiod, a creature fearful, great, swift-footed and strong, who had three heads, one of a grim-eyed lion; in her hinderpart, a dragon; and in her middle, a goat, breathing forth a fearful blast of blazing fire. Nor are they likely to resemble the Sphinx as visualized by Gustave Moreau. In another way – as the product of human science, rather than mythopoeic imagination – they are even scarier: the harbingers of a new wave of genetic manipulation, producing (and killing) creatures that are part human and part animal.

At the head of this column I could have posted the well-known photograph of a mouse with a human ear growing out of its back… except I couldn’t bring myself to do so, it looked so disgusting, poor thing. Such experiments, done in the name of medicine, indicate the extent to which all sense of the dignity and mystery of biological life has been lost. Animals – including human beings – are regarded as nothing more than machines, to be mended when broken, cannibalized for spare parts, or reconstructed into something else.

If such hybrids are close enough to human to be useful in research, are they not too close for us to treat them this way? Dr Helen Watt, the Director of the Linacre Centre for Health Care Ethics, advising the English Catholic Bishops, writes that: ‘We cannot safely assume that this procedure will not create a real, though damaged, human embryo, who will have no human parents, and whose quasi-mother is a non-human animal. This is a further offence to the embryo whom we plan to destroy, in that its very humanity will be called into question. Even if there were no risk of creating a genuine human embryo, it is a form of reproductive perversion to use a human nucleus to substitute in this way for animal reproductive material. The unique dignity of the human species, for which life and reproduction have a special meaning, needs to be safeguarded.’

* More information on this subject from Scientific American:
‘Irving Weissman of Stanford University and his colleagues pioneered these chimera experiments in 1988 when they created mice with fully human immune systems for the study of AIDS. Later, the Stanford group and StemCells, Inc., which Weissman co-founded, also transplanted human stem cells into the brains of newborn mice as preliminary models for neural research. And working with foetal sheep, Esmail Zanjani of the University of Nevada at Reno has created adult animals with human cells integrated throughout their body.

‘No one knows what the consequences will be as the proportion of human cells in an animal increases. Weissman and others, for example, have envisioned one day making a mouse with fully “humanised” brain tissue. The lawyer developmental programme and tiny size of this chimerical mouse fairly guarantee that its mental capacities would not differ greatly from those of normal mice. But what if human cells were instead put in the foetus of a chimpanzee? The birth of something less beastly could not be ruled out.

‘The intermingling of tissues could also make it easier for infectious animal diseases to move into humans. Diseases that hop species barriers can be particularly devastating because the immune systems of their new hosts are so unprepared for them (the flu pandemic of 1918 is widely believed to have sprung from an avian influenza virus).

‘There are currently no international standard governing chimera experiments. Canada’s Assisted Human Reproduction Act of 2004 banned human-animal chimeras. The US has no formal restrictions, but Senator Sam Brownback of Kansas proposed legislation in March that would outlaw several kinds of chimeras, including ones with substantial human brain tissue. Some institutions that supply human stem cells set their own additional limits about what experiments are permissible.’Within the US, at least, greater uniformity may emerge from general guidelines on stem cell use recommended in late April by the National Academy of Sciences. The NAS recommended that chimeras involving most animal species generally be permitted. It urged a ban on any use of human cells in other primates, however, as well as the introduction of animal cells into human blastocysts. It also warned against allowing human-animal chimeras to breed: some human cells might have managed to infiltrate the animals’ testes and ovaries. Breeding those animals could theoretically lead to the horrible (and in most cases, assuredly fatal) result of a human embryo growing inside an animal mother.’

Picture from John Singer Sargent Virtual Gallery