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The Ethics of Chimeric Research

microscopic image of human embryos

Recently, various news outlets covered the creation of the first human-monkey chimeras in China. A chimera is an organism whose cells come from two or more species. Researchers managed to develop monkey embryos containing human cells after previous attempts relied on pig and sheep embryos. While this type of research is prohibited in the U.S., the work was legal in China. 

Such projects have been conducted with the hope of developing human organs which can then be transplanted into humans and for conducting research into neurological and psychiatric diseases in humans. Even though such embryos do not progress past one or two weeks of growth, these efforts have been controversial. This is because it is difficult to restrict human cell growth to just one organ. According to Robin Lovell-Badge the concern is that without some way to restrict the contribution of human cells they could contribute to the animal’s central nervous system.

Such scientific endeavors present several ethical issues. These include concerns about animal ethics. For example David Shaw, Wybo Dondorp and Guido de Wert argue that given the limited number of organs for transplant, harvesting organs from human/non-human chimeras is a valid option so long as there is a substantial potential benefit to humans and if there are no reasonable alternatives present. 

Unlike other forms of animal research where the benefits may be less certain, harvesting human organs from a chimera would in most cases save a human life, so there is a large proportional benefit. Also, while there may potentially be other options for saving the life of a human requiring an organ transplant (such as research into artificial organs or changes to public policy requiring that people opt-out of organ donation), those options have not been established. For specific people who will die without an organ transplant there is no established alternative option. Thus, with these two conditions met, Shaw et al. argue that it is permissible to kill chimeras for their organs.  

César Palacios-González has argued that while harvesting organs of a human/pig chimera may be acceptable on such grounds, the case for great-ape/human chimera is more problematic. He argues that from a species-neutral standpoint great apes who possess qualities of self-awareness, complex social structures, and the potential to form rudimentary cultures are “borderline persons.” Because of this, great-ape/human chimeras are deserving of moral protection. 

Killing such animals for their organs would be no more morally justified than killing humans who possess less psychological capacities such as infants, toddlers, and adults with less mental capacities than great apes. Palacios-González suggest that we either accept that it is morally acceptable to kill great apes, great-ape/human chimeras and some human borderline persons for their organs, or we must reject harvesting the organs of any of them. 

While the animal rights argument covers some of the ethical issues involved with human/non-human chimeras, ethicists and philosophers also recognize the distinct ethical concerns presented by chimeric research. One of these concerns is whether it is wrong to cross species boundaries to create part-human beings. Is there some fixed line that distinguishes the human species from other animals, and should this boundary be breached?

According to some, crossing the boundary line of the human species is wrong because it is a challenge to God’s existence, however such arguments will not satisfy those who do not believe in a god. For others, crossing the species boundary is inherently wrong because it is unnatural. There are also those who would argue that is morally wrong because it would create too much moral confusion as we must determine the moral status of human-animal hybrids (for discussion, see Meredith McFadden’s “Moral Standing and Human/Non-human Hybrids”). 

On the other hand, such arguments are difficult to pin down because the concept of species is complicated. For example, according to Jason Robert and Françoise Baylis, “Biologists typically make do with a plurality of species concepts, invoking one or the other depending on the particular explanatory or investigative context.” 

One concept of species holds that species are defined in terms of reproductive isolation. If two populations of creatures do not successfully interbreed, then they belong to two different species. However, this definition only applies to species that reproduce sexually. Another definition considers the lineage of a population of organisms and its continuity over time. Such a definition is more encompassing but also more vague. Operationally it can be very difficult to arrive at a set of traits or qualities that completely distinguishes one species from another.  

The scientific conception of species, therefore, is not fixed. There are many ways to describe species, and it can be very difficult to arrive at a specific and distinctive definition of what makes homo-sapiens a distinct species. Because of this, the notion that it is immoral to cross species boundaries is problematic because it is difficult to define the human species in a fixed way. 

On the other hand, as Robert and Baylis point out, the fact that scientists do not have an account of fixed differences between species does not mean that the ethicist couldn’t employ a fixed account. They explain, “notwithstanding the claim that biologically species are fluid, people believe species identities and boundaries are indeed fixed and in fact make everyday moral decisions on the basis of this belief.” They use the example of race as an analogy; where race is not a biologically useful concept, but it can be a socially useful concept. 

If there are good reasons to adopt fixed notions of species for ethical purposes, then there may be a basis to claim that it is wrong to cross the species boundary, particularly because of the moral confusion it could create. Settling some of these issues will likely require that the public take note of the tension that can exist between a scientific account of something and an ethical account. Should we pursue a more open concept of species and of moral status in line with an experimental approach to these issues, or should we rely on the concept of fixed distinctions when it comes to moral matters. The issue of animal/human chimeras asks us to consider what, ethically, does it mean to be human and what does it mean to be a person?

Passing the Mirror Test and the Wrong of Pain

Photograph of a striped fish called a cleaner wrasse in front of coral with another different species of fish in view behind

In mid-February, scientists announced progress in developing an understanding of consciousness. An international team collaborating in four countries discovered patterns of brain activity that coincide with awareness. Consciousness has long been a mystery, and there are many reasons to explore and figure it out. It seems like creatures who have some form of consciousness make up a special club, experiencing the world with more layers, perhaps with more complex agency, perhaps uniquely making up the moral community.

These potential steps forward in understanding our brain-based and embodied consciousness come alongside a purported broadening of the group of animals that scientists claim pass the mirror-test for self-awareness. As we try to put our fingers on what it means to be conscious, in the last century Western philosophers have become open to the idea that there is a rich arena of animal perspectives alongside our own. The variety of ways that we can imagine experiencing the world has grown with our study of human and non-human animal experiences. This has interesting implications for who we include in our understanding of our moral community and how we understand the ways we can harm these members.

Though it is pretty intuitive that causing harm is bad, explaining why can be notoriously difficult. One route is appealing to the negative experience of harm – primarily how bad experiencing pain is. This focus unites human and non-human animals that can feel pain into one morally relevant domain. If what is bad about causing harm is that it brings about this negative experience of pain, then we need to identify the sorts of creatures that experience pain and avoid bringing about those states without outweighing reasons. Thus, consciousness will be morally relevant insofar as it delineates those creatures that are in some way aware of their experiences.

There are two responses to this line of thinking. One direction argues that this grounding of the badness of causing harm is too narrow: there are harms that we don’t experience, so this understanding misses morally relevant behaviors. Another direction claims that this line of thinking is too broad: not all pain is morally relevant.

Consider the (false) common conception of the perspective of a goldfish, where their understanding of the world resets every 10 seconds. Would causing pain to a creature who would very quickly have no memory of it have the same moral relevance as causing pain to something that would incorporate it into its understanding of the world indefinitely? Take the faux-goldfish example to its conceptual extreme and imagine a creature that has the experience of pleasure and pain, but only has instantaneous experiences – it lacks memory. Presumably, it wouldn’t matter to the creature a moment after it felt pain that it felt pain a moment ago because it had no residual impact from the experience (unless prolonged damage was done). If you share this intuition, then something more than the mere experience of pain is involved in the morality of causing harm.  

The way to make pain morally relevant is to focus on the perspective of the creature experiencing the pain – that there is such a perspective extended in time that experiencing the pain will impact. We can imagine the fear of a non-human animal in unfamiliar circumstances and consider the anxiety that may develop over time if it is continuously exposed to such circumstances. Such creatures have a sort of “self,” in the sense that their experience of the world develops their mode of interacting with the world and understanding of the world over time.

There is an even more advanced way of being a creature in the world beyond stringing experiences together in order to have a perspective extended in time: a creature can be aware that it has such a perspective by being aware that it is a self.

A key experiment to check the development of a self-concept is the mirror-test, where an animal has a mark placed on their body that they cannot see by moving their eyes. If, when they see the mark on a body in a mirror, they come to the conclusion that their own body has the mark, then they “pass” the mirror test because in order to come to such a conclusion the animal must use an implicit premise that they are a creature that could be so marked. The mirror-test is thus meant to indicate that an animal has self-awareness. It relies on a variety of competencies (vision and figuring out how mirrors work, for instance), but has long been thought to be sufficient for indicating that a creature is aware that it exists in the world.

Humans don’t pass the mirror test until they are toddlers, and only some primates also are able to pass the test, along with sundry birds and other mammals. However, this past year a tiny fish – the cleaner wrasse – seemed to pass the test. It is a social animal, considered to be relatively cognitively advanced, but the scientists who advocated for the results of the mirror-test suggest that while yes, this is a smart and advanced fish, this may not mean that it is self-aware. The success of the small fish has raised issues in how we test for morally relevant milestones in non-human animals.

One interesting facet of the mirror test is that animals that perform well are social, which is often a morally relevant trait. If morality is a matter of treated others with the sort of deference they are due, then a sort of sociality for members of the moral domain makes some sense.

In defining our moral community, most theorists include some non-human animals, and most consider it relevant to identify the way creatures experience the world. These latest advances in mapping consciousness and advancing our interpretation of self-awareness tests will help us understand the spectrum of relationships possible in the animal world. 

This article has a set of discussion questions tailored for classroom use. Click here to download them. To see a full list of our discussion questions, check out the Educational Resources page.