Experiments to make animals look, sound or even think like people could soon be on the research agenda, according to a UK scientific body that has warned politicians and the public to start considering the implications.
So far humanisation of animals has been limited to the insertion of relatively small numbers of human genes or cells into laboratory animals, mainly mice. This has led to many advances in understanding the causes of diseases and devising treatments for them, without triggering regulatory or ethical concerns beyond those already associated with animal research.
The academy’s review is based on what might happen in the near future, given the rapid pace of biological research.
“We are not aware of any work going on now that is likely to cause anxiety, but we wanted to take a proactive look at an area of science that has not received much public attention,” said Martin Bobrow, a medical genetics professor at Cambridge university who chaired the inquiry.
The review identified three types of experiments that might soon become possible and would cause particular concern: modifying animal brains to mirror human “cerebral function”; fertilising human eggs or sperm in an animal; or endowing animals with characteristics perceived as uniquely human such as facial shape, skin texture or speech.
Mice with human livers are already used in toxicology research. US scientists have also created mice in which one-quarter of the brain cells are human neurons, and they have discussed – but not gone ahead with – making a mouse in which all neurons are derived from human stem cells.
“If you replaced an entire mouse brain with human neurons, it would almost certainly still be a mouse, though with some interesting changes,” Prof Bobrow said. “But for something with a bigger and more complex brain, such as a primate, it is hard to guess what the result would be.”
Another controversial move would be to make animals sound like humans. A gene associated with human language has been transferred to mice. “These animals vocalise slightly differently from ordinary mice – but they don’t speak,” said Robin Lovell-Badge, head of stem cell biology at the National Institute for Medical Research.
“If you come home and your pet parrot says, ‘Who’s a pretty boy then?’, that’s one thing,” added Christopher Shaw, neurology professor at King’s College London. “If your pet monkey says it, that’s another.”
The academy recommends that the Home Office, which regulates animal experiments in the UK, establish a national expert body to provide specific advice on sensitive types of research involving humanised animals.