US scientists are creating novel life forms: “human pig chimeras”. These are a blend of human and pig characteristics. They are like mules who will provide organs to us. A mule is the offspring of a male donkey (jack) and a female horse (mare). Horses and donkeys are different species, with different numbers of chromosomes but they can breed together.
In this case, they take a skin cell from a person and turn it back in time to make stem cells capable of producing any cell or tissue in the body, “induced pluripotent stem cells.” They then inject this into a pig embryo. This makes a pig human chimera.
However they do a modification to the pig embryo first. They use gene editing, or CRISPR, to knock out the pig’s genes which produce an organ, say the pancreas. The human stem cells for the pancreas then make an almost entirely human pancreas in the pig human chimera. It functions like an organ mule. (The blood vessels are still porcine.)
In this way, your skin cell could grow a new liver, heart, pancreas, or lung.
This is a technique with wider possibilities: other US teams are working on a chimera –based treatment, this time for Parkinson’s disease which will use chimeras to create human neurones.
CRISPR is also credited with enhancing the safety of this technique, with the BBC reporting that a Harvard team were able to use the new and revolutionary technique to remove copies of a pig retrovirus.
Safety is always a major concern when science crosses new boundaries. But even if a sufficient guarantee of safety could be reached, are there ethical problems?
A chimera is a genetic mix. This means that, although the aim may be to isolate only certain organs to express human genetic material, the whole chimera will in fact comprise of the genetic material of both humans and pigs. It is not a pig with a human pancreas inserted into it, it is a human-animal chimera, whose pancreas resembles a human, and whose other organs resemble a pig.
This potentially has effects on the chimera’s brain. Ross, the lead research in the pig experiment is quoted by the BBC saying “We think there is very low potential for a human brain to grow”.
Even if in this particular case he is correct, given that some of this kind of research is indeed focussed on neurons, it is not impossible that the functioning of the resulting chimera may be affected in some chimeras in the future.
Where the genetic material of human and animals are mixed, this may express in characteristics that we usually consider to be moral status –affecting. “Moral status” is the standing or position of a being within a hierarchical framework of moral obligations. The moral status of a chimera entails relevant obligations to treat it in certain ways while it is alive, in virtue of its nature, and whether it is wrong to kill it.
How should we respond to chimeras when we are uncertain of their functionality and status? At present, they are destroyed as embryos. But to harvest organs as the scientists hope, full gestation would be needed. When that happens, we should not simply accept that a spade is a spade: if a spade looks the same as it always has, but can now function as, say, an electric guitar, it may have become something else entirely.
Research to determine the being’s nature and moral status should be performed before use by humans
If there is any doubt about the cognitive abilities of this new life form, we should check the chimera for its functionality. We should not assume it has the cognitive function of a normal pig, we should assume it. We should rear it humanely with social contact and assess its function and abilities as it develops.
Moral status and what types of abilities or attributes confer it and to what degree, has been the topic of whole libraries-worth of philosophical discussion. Candidates include species membership, sentience, higher cognitive functioning, and personhood.
The chimera would need to be assessed against these types of criteria. This is by no means simple: consider two examples:
- If synthetic biology created a network of neurons in vitro, could it become conscious? If so, how would we know if it had?
- Rats have been created with a lesion in their brains that scientists believe, based on their behaviour and on human descriptions of similarly placed lesions, causes rats to experience pain differently. Rats with the lesions experience the sensation, and would flinch as normal rats do when presented with a painful stimuli. However, they do not learn to avoid the pain as normal rats do. Even if we were right about these rats and their experience of pain, would we be justified in inflicting painful stimuli on them?
So there are barriers both in knowing the relevant facts about a chimeras moral status, and in assessing how relevant facts affect its moral status.
If research is not yet done or fails to yield useful results, the chimera should be accorded the highest moral status consistent with its likely nature
We should err on the side of sympathy and generosity. If there is a chance a new life form could experience pain or might not be able to interact socially, and we don’t know, it should be treated as if it experiences pain and will have problems of social adaptation. Likewise, if it could plausibly have higher cognitive functions, it should be treated as if it would have them.
One final note: pigs are already thought to have greater cognitive ability than we have previously credited them with: it is not a given that we have already assigned the most vanilla of pigs an appropriate moral status when we, for example, factory farm them.