Is a brain a human being?


Is the mind all that matters?


What makes us human? What is the smallest set of organs necessary to make a human? How far can you reduce the body until what is left cannot be considered alive? What about the soul? Some previous cultures considered the heart or the bowels to be the very core of humanness. In the 17th century, the French philosopher René Descartes made the famous statement “Dubito, cogito ergo sum”, meaning “I doubt, therefore I think, therefore I am”.1 What Descartes meant by this statement, is even if we doubt everything that our senses are telling us, we can still sense our own mind at work. In other words, our mind can think about its own self.

The brain is the physical seat of cognition and all mental activities. All sensation ends up in the brain, where it is organized, interpreted, and responded to. According to some clinical definitions, a person is pronounced dead if his brain ceases to function, besides the cessation of circulation and respiration. The body cannot function if the brain does not function at a basic level. Surgeons have even been able to perform head transplants on monkeys and are planning to perform them on human subjects.2 This shows how important the brain is to the rest of the body. Therefore, some people say that the mind is the seat of our humanness.

Organoid experiments

Muotri Lab, UCSDbrain-organoids
Brain organoids grown in the lab.

This being said, would it be possible to isolate the mind from the rest of the body and artificially keep it alive? Why even ask this question?

Researchers who wish to study the development of the nervous system and certain neurological diseases cannot simply run life-threatening tests on people’s brains while they are alive. That is a clear ethical violation.

That is why in recent years, scientists have been culturing brain organoids for the opportunity to model early neural development, and study drug effects on the mind, as well as mental illnesses, such as autism, microcephaly, and schizophrenia.3 Researchers also want to study brain organoids so they can compare them with those of ape species in evolutionary studies.

An organoid is a mass of tissue which comes from an organ of a person’s body, such as liver cells, which researchers use as a miniature model to study biological processes happening in the real tissue or organ. Hence the term organoid, denoting a smaller version of the organ. Organoid studies are preferable to studies done on entire embryos, since only a single organ is being modeled. This way no ethical issues arise concerning the use of human subjects in medical studies.

Brain organoids come from human body cells, such as skin or blood cells, which are re-programmed into so-called ‘pluripotent’ stem cells. These are cells, which have general cellular characteristics. They do not fulfill any specialized function in the body, such as muscles cells or bone cells, which are involved in movement or body structure. Some of these pluripotent stem cells can then differentiate into brain cells and can even self-organize into three-dimensional structures resembling a human brain.4

Brain organoids are about one-millionth the size of normal brains (see figure 1). Their disadvantage is that they do not contain all the types of cells in the brain of a mature human being. Researchers can use them to model diseases only imperfectly. Furthermore, the test tube environment that they are grown in isn’t the same as the uterus, where a baby normally develops, which is a very important factor during human development. This is because the uterus is a more suitable environment than a Petri dish for human development. Because brain organoids lack blood vessels and other cell types which are necessary for further growth, brain organoids generally rot after a while.

Cells in brain organoids even separate into different cell layers, which is reflective of finer tissue structure. Brain organoids also show differences in structure when grown from normal brain cells and between those which were grown from patients with autism spectrum disorder (ASD).5 However, even though the brain organoids develop separate regions, these regions are not exactly the same as in a real, normal brain, because they cannot sense the axis of its non-existent body.

Recently, Dr Alysson Muotri, a professor at the School of Medicine at the University of California in San Diego has been able to detect brain waves emanating from brain organoids that he has been studying. These brain waves appeared at two months of development, which is characteristic of very immature human brains. After the brain organoids developed further, their brain waves appeared more regularly and at different frequencies, indicating that the brain organoids’ nervous system had become more developed.6 This gave rise to concerns by these researchers as to how far they can go with developing brain organoids, which, in their view, might be showing the first signs of consciousness.

Is it right to grow brains in the lab?

If the mind is the seat of our humanness and we are now capable of growing brains in Petri dishes, this raises a whole slew of ethical questions. If brain organoids can produce brain waves, what exactly is it sensing? If the organoid reacts to stumuli, is it just a physical response, or does it consciously feel pain? Does the brain organoid have a soul? Is it a person? If so, does it have the same rights as everyone else? What do we do with brain organoids grown in the lab which are not needed anymore? Since organoids are harvested from living individuals, this would mean that the organoids are clones of human body parts. But since, unlike many other body parts, we cannot live without our brains, this might lead some to wonder whether a laboratory brain is not merely a body part, but an individual person. This might also raise the question of whether clones are fully human?

On 21 Oct 2019, researchers from the Green Neuroscience Laboratory in San Diego urgently called for a definition of what point a brain tissue can be considered sentient (conscious).7 This is important, because after a certain stage, some researchers argue that brain organoids might be able to sense pain. Of course, this is debatable, but the question is worth considering, so that researchers do not induce unnecessary suffering, even if it is ‘just’ a mass of tissue.

Researchers have no way of determining whether brain organoids are truly conscious. The best that they can do is to apply tests that are used on brain-injured non-communicating patients, but these tests are very limited.8 The problem is made all the more difficult since pain is subjective—we can’t get inside the brain organoid to determine how much it could be suffering in the case that it turns out the entity is more than a mass of tissue.

The fact that researchers have been growing brain tissue in the lab for some years now without seriously asking these questions is an indication of the lessened value of human life nowadays. These ethical questions should have been the first thing to resolve before such experiments were even allowed. Think about it—would you be happy if researchers thoughtlessly conducted tests involving highly radioactive material near your town without your consent?

The way the world views it, experiments on possibly conscious brain organoids might be worth it, if the risk to benefit ratio is low enough. In other words, it’s worth sacrificing even conscious brain organoids in order to help cure mental disorders. One secular author writes “On the one hand, we may have the interests of a patient with Alzheimer’s disease who is likely to fall into total oblivion, and on the other hand the suffering of an entity comparable to a very simple lifeform that we would usually be willing to sacrifice in the face of the interests of a human being.”8

This brand of humanistic ethics is called hedonistic consequentialism, which decides whether a given action or policy (such as growing brain organoids) is ethical based on its ‘intensity, duration, certainty, availability, purity, fecundity (abundancy), and extent (number of affected people).’9 Its goal is to maximize well-being and minimize pain, hence the name hedonistic. However, researchers cannot accurately foretell future consequences of such tests on brain organoids. For example, when in vitro fertilization techniques were first made available, it was not yet known that these techniques cause a small, yet significant rise in the number of birth defects.10 Moreover, protocols for even larger, more developed brain organoids have not yet been developed. This makes forecasting the effects of brain organoid research even more uncertain.

In comparison, many secular researchers conducting experiments on embryos draw a boundary at 14 days, because this is the latest time point when a mother can have twins. In other words, at 14 days the human embryo is still not yet developed enough so that it can fall apart without any consequences to both twins which are a result of the split. At this stage the embryos have not yet developed a neural tube,11 meaning that the embryo at this early stage does not feel pain. We point this out not to endorse the drawing of the boundary lines here, but to say that this is at least preferable to a situation where there are no boundary lines, as is the case currently with brain organoid research. A human embryo should have the right to life in virtue of being a whole, distinct, living human, regardless of its stage of development or ability to feel pain. Twinning can be understood as a type of natural cloning, so does not demonstrate that the earlier embryo is a non-individual.

Experiments have been conducted by scientists on other kinds of organoid tissues for years. For example, cancer researchers have been studying liver cancer using organoid cultures, which are clumps of cancer cells in a Petri dish. Some kinds of cancer cells have been kept alive in test tubes for years, for example the HeLa cells from a cancer patient called Henrietta Lacks, who died of cervical cancer in 1951. These types of tests are different from brain organoids, since they don’t involve the brain, an organ which we cannot live without, and through which we control the rest of our bodies. Our skin sheds cells all the time as the skin grows. We can lose blood from an open wound. An amputee can lose a limb, but the loss of all of these other organs do not make us less human.

In the case of brain organoids, it might not yet be a problem if the tissues are grown until a certain stage. A single nerve cell does not yet constitute an entire brain. Researchers study individual cells in the lab all the time, without any ethical concerns. Single brain cells in isolation show biological activity just like any other kind of cell. There’s also the question as to whether brain organoids really can feel pain, if they don’t have any pain receptors relaying signals to the brain. With brain organoids we don’t have the exact same problem as with abortion, where life must be protected at all costs starting from the fertilized egg, since life starts at conception.

Furthermore, even if we could grow an entire human brain in the lab that was fully functional, physically speaking, this might pose no ethical difficulties if the isolated brain turns out to be merely a body part rather than a whole individual human being. An artificially grown brain, unlike the human embryo (however it was conceived), would not have the capacity to self-direct its own development (in the proper environment) to grow a complete human body. Thus, it would arguably not have a soul, not be conscious, and not truly feel pain or feel anything at all. But these are the issues that ethicists must address before the research recklessly marches onward.

Nevertheless, ethical concerns regarding brain organoids still arise. What should we do with these organoids after we have used them? Would it be permissible to destroy them? If they are conscious, and if they produce cell layers much like normal brains, then it might not. Should we store them in refrigerators at extremely low temperatures in a state of suspended animation? This is what they do with surplus embryos which have been created in a Petri dish for infertile couples. But is this the right thing to do with something you could consider to be a human entity? Would you assent to being put unconscious and being stored in a refrigerator for decades? On top of this, would you also assent to being denuded of your entire body and stored in a jar full of culture medium?

Maybe not.


The study of brain organoids has very complex and far-reaching philosophical and ethical consequences. We stand to gain a lot of medical knowledge using organoids in order to alleviate human suffering. For example, one potential application of organoid research is growing personal organs from an ailing patient to run experiments on their duplicated organ. This way we can find an accurate, personalized cure for patients with minimal pain and intervention.12

In the meantime, we should not proceed with research until we know whether the subject of our study is a human person. If these brain organoids are mere tissues—with no soul, no awareness, no individual personhood, then the above concerns are alleviated. But if we think they could be undeveloped yet complete individuals made in God’s image, the picture changes dramatically.

The most important issue at stake here is the value of human life. The world considers human life as possible subjects of medical studies without consent. Fetuses are labelled as a more primitive stage of evolutionary development (often based on Haeckel’s fraudulent embryonic recapitulation theory), meaning that it is permissible to abort them. In a similar vein, brain organoids are considered more simple life forms with a diminished level of consciousness. According to secular thought, it does not matter whether brain organoids are full-fledged members of the human community. Given their level of physical development, they can be disposed of just like aborted embryos.

God’s Word presents a different picture of human life. Psalm 139:13–14 says “For you formed my inward parts; you knitted me together in my mother’s womb. I praise you, for I am fearfully and wonderfully made. Wonderful are your works; my soul knows it very well.” An embryo is fully human, even from a single-cell stage. That is the fundamental question we must ask of a brain organoid as well. If it gains consciousness, then we would have to consider it human too. We may neither abort the fertilized egg cell nor conduct any kind of experiments on embryos, nor may we destroy the conscious brain organoid. Whereas we must allow the fertilized egg cell to live and develop into a mature human being, we must also do no harm to any other human life if it is found to be such.

Published: 12 December 2019

References and notes

  1. Descartes, R., Discourse on the Method, Amsterdam, 1656. Return to text.
  2. Suskin, Z.D. and Giordano, J.J., Body-to-head transplant; a ’caputal’ crime? Examining the corpus of ethical and legal issues. Philos Ethics Humanit Med. 13(1):10, 2018. Return to text.
  3. Di Lullo E. and Kriegstein, A.R., The use of brain organoids to investigate neural development and disease, Nat. Rev. Neurosci. 18(10):573–584, 2017. Return to text.
  4. Kelava, I. and Lancaster, M.A., Dishing out mini-brains: Current progress and future prospects in brain organoid research, Developmental biology 420(2):199–209, 2016. Return to text.
  5. Mariani J. et al., FOXG1-Dependent dysregulation of GABA/glutamate neuron differentiation in autism spectrum disorders, Cell 162:375–390, 2015. Return to text.
  6. Stetka, B., Lab-grown “Mini Brains” can now mimic the neural activity of a preterm infant, Scientific American, scientificamerican.com, 29 Aug 2019. Return to text.
  7. Martin, S., Blob-like brains created in lab could have ‘thoughts’ and are ‘suffering’, scientists warn, express.co.uk, 22 Oct 2019. Return to text.
  8. Lavazza A. and Massimini M., Cerebral organoids: ethical issues and consciousness assessment, J. Med. Ethics 44(9):606–610, 2018. Return to text.
  9. Holmes, Arthur F., Ethics: Approaching Moral Decisions, Second Edition, IVP Academic, Downers Grove, IL, 2007, p. 45. Return to text.
  10. Davis, John J., Evangelical Ethics, Third Edn, Presbyterian and Reformed Publishing, Phillipsburg, NJ, 2004. Return to text.
  11. The neural tube is the first stage of development of the nervous system. Return to text.
  12. Clevers H., Modeling development and disease with organoids, Cell 165(7):1586–1597, 2016. Return to text.

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