What pro-lifers don’t realise about induced pluripotent stem cellsSunday, 4 May, 2008
It is often claimed by the pro-lifer crowd that induced pluripotent stem cells (iPSCs) are a great way to sidestep the nasty ethical issues of embryo-derived stem cells. Because, as you all surely are aware, an embryo is a unique human being. But clearly they either don’t understand the science behind iPSCs or don’t think about their pro-life arguments for the protection of the human embryo.
iPSCs are human life
It is often claimed that conception marks the beginning of a new life. But all human cells are alive, just as bacteria are alive. You can kill your own cells, such as killing brain cells by drinking alcohol. These are human cells, as they contain human DNA and would be classified as such. To be strictly true, life began four billion years ago, and hasn’t stopped since. Sperm are alive, and so are ova. There is a continuum of life stretching back to a single point for all creatures (just as all your siblings could be traced back to the zygotes that formed your mother and father, all creatures can be traced back to few cells billions of years ago)
Therefore, as induced pluripotent stem cells are created with the same DNA as would be found in living human skin cells, they are also human life – both human and life. Therefore, if we are supposed to be protecting human life, then we can’t use iPSCs.
iPSCs have a unique human genome
It is often claimed that because the embryo has cells which are distinct from the cells of the mother, they represent a new human being. But if a woman was to receive treatment with iPSCs, they would also be cells that are genetically distinct from the mother, and indeed anyone else on the planet. iPSCs are genetically engineered cells: genetically-modified into becoming pluripotent. A retrovirus is used to insert genes essential for pluripotency, and these can insert in random locations on the genome. Therefore, they contain a unique human genome that would not be found in any other organism. So, if cells with unique human genomes represent humans worthy of protection, then iPSCs are in the same category as embryos.
iPSCs are potentially human beings
I’ve often heard it argued that we should treat embryos as full persons because they have the potential to become full persons (or, because they have ‘inherent capacity’ to become persons). Even if we ignore the the most obvious failure of this argument (young children are potential adults, but it doesn’t follow that we should give them the right to vote. Adults are potential seniors, but they won’t get a senior’s discount. Seniors have the inherent capacity to be dead, but we should not treat them like they are corpses), and assume that something with potential to become a fully functional human being should be treated as such, we are still left with the inability to use iPSCs.
A zygote has the potential to become a human child, but is it not also true that sperm and ova have the potential to become a zygote? And, embryonic cells, and embryonic-like iPSCs, have the potential to form sperm and ova (even though nobody has done that yet). So it clearly follows that if potential is just as good as the real thing, then iPSCs are just as good as you and I. And because any (diploid) adult cell has the potential to become an iPSC, then all human cells are equal to human beings. Unless, of course, potentiality is irrelevant.
In addition, though slightly outside the scope of this blog entry, it may soon prove possible to created induced totipotent cells (iTCs)- that is, to insert genes that would turn a stem cell into a cell identical to a cell found in a zygote. An iTC would have the capacity not only to form sperm which could form a zygote which could form a full human being, but it would also already be a zygote: a clone of person who gave the cells from which the iTCs were derived. So, clearly conception cannot be a significant event, because it is possible to bypass it and end up with a person like you or I.
I don’t actually think iPSCs are worthy of protection. I do, however, think all of these pro-life arguments I’ve heard are useless, as I hope I’ve shown by the reductio ad absurdum above. I think that the right to life is only applicable to a lifeform that is ultimately valuable – that is, valuable to that lifeform itself. To quote British ethicist John Harris
I suggest there is only one thing wrong with dying and that is doing it when you don’t want to. (Harris J, 2003)
A necessary requirement for some organism to value its own life is self-awareness, which is a feature found only in a few brainy creatures (chimps, gorillas, elephants, dolphins etc), and only appears in humans at around 18 months of age. So I tend to agree with those people who say consciousness is a requirement for a right to life, although I would argue that technically it requires at a minimum only one characteristic of higher consciousness – the capacity for self-awareness.
This seems to me to help clear up a common argument put forth against the consciousness view – the protection of humans in subconscious states, such as sleep. Consider an analogous situation. The answer to the question “Does he speak English?” remains the same even though the boy/man may not be English at the time, or may not be speaking at all if he is asleep. If the answer is yes, then this person does have the ability to speak English but isn’t currently doing so. This is not relying on a potential ability to speak English – he is able to speak English. On the other hand, if he has never learned English, it could only be said that he has the potential to acquire the ability to speak English – he is not yet able to speak English, but potentially could be able in the future.
Likewise, you could ask ‘Does he value his life?’ and the answer should not change whether the person is asleep or not currently thinking about their death. On the other hand, an embryo or brain-dead person is not able to value their life, because they have lost that ability or not yet acquired it, but could potentially acquire(or re-acquire) that ability. Consciousness is a state of being, whereas to value oneself is an ability. This is why ultimate value is better than consciousness as an indicator of how much you should respect a person’s life – you can be said to a person even if you are not conscious and therefore not presently doing valuing your life, just as you can be said to be an ‘English-speaker’ even if you are not presently speaking English.
Anyway, the key point here is that iPSCs, and embryos, are not ultimately valuable – they do not yet have a capacity for valuing their own lives, and there is no way to assume they think such an unconscious state as valuable because they have as yet never been able to even have such a thought. And yes, I know that later in life when those cells have turned into you or I they will value their embryonic state in retrospect because it led to their existence, but such people would also value the state when they were comprised of an ovum and sperm, or when they were comprised of iPSCs that were stimulated into making that ovum and sperm – all necessary for their existence (you could even go back 4 billion years). But the important thing is that they have not as yet had the ability to make such value judgements, and as such do not need to be respected. After all, we don’t respect bacteria just because they have the potential to evolve into sentient beings that could, in billions of years, value their prior existence as bacteria.