The furore over potential cross-species research echoes vaccination fears of the 1800s, says Deborah Brunton
A wave of monsters has invaded the newspapers: moo-tants and Frankenbunnies. These creatures - the products of fertile journalistic imaginations - have apparently been sent to warn us of the dire consequences should the Human Fertilisation and Embryology Authority permit researchers to create chimeras.
Such organisms are made by replacing almost all the DNA in a cow or rabbit egg cell with human DNA to create an experimental tool to trace the progress of disease and, perhaps one day, to act as sources of stem cells to repair organs and to treat degenerative conditions.
The shock headlines seem born of an unholy liaison between tabloid journalism and 21st-century fears about medical science, but we have been here before. In 1802, James Gillray published a cartoon titled "The Cow-pock - or - the Wonderful Effects of the New Inoculation!", which showed cows' heads and tails erupting from the bodies of people who had just undergone the new procedure of vaccination against smallpox. Although Gillray possessed a sometimes cruel imagination, his cartoon was based on observations by medical practitioners. They reported vaccinated children developing patches of hair, running around on all fours and coughing like cows. One medical man published the case of the unfortunate ox-faced boy, a vaccinated child whose face swelled.
We may now laugh at such accounts as naive and nonsensical responses to a discovery that could claim to have saved more lives than any other medical development. But public reaction to the prospect of chimeras is remarkably similar. A government consultation found strong opposition based on the "yuck" factor: an instinctive reaction that it is against nature. Smallpox vaccination and the creation of human-cow or human-rabbit chimeras both threaten to blur a fundamental divide between animal and human.
The concern in 1800 was more understandable. On the one hand, the benefits of vaccination were clear: it held the promise of protecting children from smallpox, a disfiguring and often fatal disease. And it had none of the risks associated with the older technique of inoculation: deliberately infecting children with a mild form of smallpox to confer immunity. But, on the other, the risks were great. The new procedure was practised on infants - innocent and full of promise. And giving a child one disease to prevent another was an outlandish idea: it had no precedent. More alarmingly, no one had any idea how it worked. Edward Jenner had discovered vaccination by testing the observation that milkmaids who had suffered from cowpox did not catch smallpox. In an experiment that no modern funding body would ever sanction, Jenner tested the theory by deliberately infecting a small boy with the two diseases in turn.
By comparison, the science of chimeras is far better understood. The technique of producing the embryos is firmly rooted in an established body of knowledge about the behaviour of dividing cells. Unlike vaccination, the use of chimeras holds promise of a better understanding of disease, particularly of degenerative illnesses such as Alzheimer's. Access to large numbers of stem cells - far greater than could be found from human donors - holds the prospect of treating incurable conditions and repairing damaged organs. Yet the public is not willing to take the risk of permitting research that may produce treatments for the diseases of old age.
The history of vaccination does not offer much hope to researchers eager to press forward with the development of chimeras. Though fears of infants turning into cows had faded by the 1810s, from the 1850s a vocal anti-vaccination movement arose that argued that a vaccine based on an animal disease was dangerous when introduced into humans. Opponents claimed the vaccine poisoned the blood and that children died as a direct result.
Anti-vaccination magazines carried images of the dead infants. They also claimed that among those who survived, the vaccine undermined their constitutions, leaving them weak and susceptible to other diseases.
All efforts to educate the anti-vaccinationists of the merits of the practice failed. Opposition died only when children were excused vaccination if their parents declared their conscientious objection to the practice. Similarly, all the reassuringly scientific arguments about the tiny amounts of animal DNA in chimeras, about the short time the embryos survive and about the tight regulation of their use, are unlikely to dispel the "yuck" factor. Arguments alone will not quell public fears of crossing a divide between animal and human and the spectre of the Frankenbunny.
Deborah Brunton is a senior lecturer in the history of medicine at the Open University.