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    I confess: I don't know when human life begins
    By Paul Knoepfler | July 11th 2011 12:23 PM | 19 comments | Print | E-mail | Track Comments
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    Associate Professor of Cell Biology and Human Anatomy at UC Davis School of Medicine. Long-time stem cell and cancer scientist. Cancer survivor...

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    I confess.

    I don't know when the life of a human being starts.

    But, I do have some thoughts on the topic and I believe I know for myself when life does not begin. Most scientists are afraid to talk publicly about this question and probably for good reason given its controversial nature.

    It would seem there are supposed to be three main authorities on when life begins. 

    First, those with moral authority. They base their perspective on their own personal moral and ethical beliefs, often based on their own religion. 

    Second, there are doctors. Many people think that because of their medical training that doctors have a unique, rigorous perspective on when life begins for human beings. 

    Third, there are scientists. A lot of people turn to scientists hoping for some kind of scientific proof of when life begins.

    I would argue that none of these three types of authorities have the answer because there is no "the answer" that applies to everyone.  Regrettably, there is no experiment to determine when life begins although one scientist argued there was and I rebutted her claims in this blog post.

    There is no equation like E=MC2 for defining the moment when a human life begins.

    To me personally, there are six mains possibilities when the life of a human being might start: (1), before conception (yes, you read that right), (2) at conception, (3) at implantation, (4) when distinctively human, organized brain activity begins, (5) when the fetus can survive outside the womb, and (6) at birth. 

    Let's talk about these in order of timing, but first I wanted to note that in a poll on my lab's blog the most popular answer by far was (5). You can see the poll results and vote here.

    First, we have the possibility that a human life starts before conception. This may seem counterintuitive at first, but let me explain. Most of the time for a human embryo to start growing, a sperm has to fertilize the egg forming a zygote, which then begins dividing and producing the embryo. However, sometimes, an egg spontaneously starts the process of development on its own in an event termed parthenogenesis.  

    Parthenogenesis occurs widely throughout life forms on Earth, but as far as I know it has not been proven to have naturally occurred in humans. Even so, given the number of people on Earth, I think it is likely that it has happened even if it has not been documented. It can also be stimulated in a lab and there is no reason why parthenogenesis could not theoretically produce a normal human female if the embryo was implanted in a surrogate mother.  So in theory, a human egg has the potential to create a living human being. Thus, one might argue that a human egg is a living human being because of this potential. To me, this seems like a stretch, but keep it in mind as we go forward with our discussion.

    Second, there is the idea that the life of a human being begins at conception. The case for conception is fairly straightforward, which is appealing in a way. It is undeniable that the first step that must be taken to end up with a living, breathing human being is conception. However, the case against conception is that a fertilized human egg is not by any stretch of the imagination an actual human being, at least not in my opinion.  The fertilized egg, also known as a zygote, has the potential to make a human being, but often it does not. From my perspective, which of course may be wrong, a fertilized egg is very much like a seed. I really like this analogy.  Let's run with it.

    OK, picture this in your mind--a small Sequoia seed that just fell out of a cone onto the forest floor in Yosemite. See it? That seed is not the same thing as a 2,000 year old Sequoia Tree, right?

    Even if that seed has the potential to become that tree over a period of thousands of years by growing trillions of times in mass and developing leaves and other specialized structures, it does not mean that that seed is a tree. 

    In fact the odds are very much against that seed ever becoming a living tree. First it has to implant in the ground, send out roots, etc.

    Key idea: Potential does not mean equality. A seed can become a tree, but a seed is not a tree. They are different. A fertilized human egg can become a human being, but that potential does not equate the fertilized egg with a human being. It has to survive, implant, grow trillions of times in mass, etc.

    So for me personally, conception is not when human life begins, but again that is not some universal "right" answer that I expect others to believe.

    Third, the life of a human being might start at implantation. In human and other mammalian development, implantation is a key event.  This happens in humans around 2 weeks after conception. I'm not sure if life begins at implantation, but I can see the appeal of this idea. It's very much like a seed sprouting into the ground. No embryo can survive without becoming attached to the uterus and forming deep connections.

    Fourth, is the idea that human life begins when the fetal brain (the most distinctive of human organs) begins functioning like a human brain. There is some debate about when this happens, but it is at the earliest in the 2nd trimester. Earlier than that a human brain can fire off random neuron activity, but it is from all evidence I've seen, nothing like the activity related to thoughts. It's like chaotic electrical activity. Even a dish of human neurons in the lab can produce such activity. What we are talking about here, as a defining point of the start of a human being, is brain activity more similar to human thought.  To me this definition is interesting, but very unclear.

    Fifth, some people argue that human life begins when a fetus can survive outside the womb. With advances in medical technology, the date at which a human fetus can survive has gotten earlier.  With rare exceptions, the earliest is 23 weeks of age, which is quite remarkable.  Again, as mentioned earlier, this notion that independent survival ability is the definition of the start of human life, was the most common answer in the poll I did (which admittedly was far from scientific). I can see the appeal of this definition, but what makes it less than ideal for me is that this point of independent survival will be different for every fetus. It's nebulous.

    Sixth, many people believe that a human life begins when a baby is born. The appeal of this idea is that birth is such a well-defined event and is indisputably the time when a mother and the fetus/baby become separated. To me personally, this definition seems too late. I think the life of a human being starts earlier, but again I am not telling you what to think.

    So overall, there is no one answer about when a human life begins, but I believe that it is a question that people should give serious thought to given its importance, particularly if you are taking a stand on embryonic stem cell research one way or another. Note that embryonic stem cells are made 100% in a lab from blastocyst embryos produced during in vitro fertilization procedures. They have nothing to do with natural pregnancies. The embryonic stem cells are made from blastocysts that are embryos that are only a few days old, that have no organs of any kind, and have only a few dozen cells. The fate of these embryos if they are not used in potentially life-saving embryonic stem cell research is most often to be discarded. Alternatively rarely they might stay in liquid nitrogen for years.

    Cultures around the world have many different answers about the start of life. For example in Islam and Judaism, life begins after 40 or so days. In other cultures it is earlier and in others it is later. 

    I personally think that everyone has to decide this question, one of the most important we can ponder, for themselves.

    Please let me know what you think!



    That seed analogy makes such intuitive sense to me about the earliest embryo not being the same as a person.

    You forgot another possibility, but as a scientist, I doubt that you will like it: the mom decides when the life has begun.

    Gerhard Adam
    That makes no sense.
    Mundus vult decipi
    Egads, my mother has been mad at me plenty.   If her Descartes-ian thinking is what makes me alive then I could be in big trouble even if I am in my 40s.

    I guess that kook who drowned her kids in her bathtub decided the kids were not alive after all.
    Gerhard Adam
    A fertilized human egg can become a human being, but that potential does not equate the fertilized egg with a human being.
    I think you're unnecessarily confusing topics.  Asking when a human life begins is not the same thing as asking what makes a human being.  A human life (other than your exception regarding parthenogenesis) begins when an egg is fertilized.  After which, it must proceed through all manner of "obstacles" until it can fully develop into a human being and survive outside the womb.  Certainly there is no guarantee that it will survive, but you certainly can't argue that while the cells are dividing they are doing it for no purpose ... it isn't just a random set of actions.  We are also confident that it will not suddenly become a dog, or a horse.  It is a human being, despite having no assurances regarding its survival or eventual birth.

    We wouldn't argue that a child that is born and lives only 6 months, isn't fully human being because their potential as an adult wasn't realized.  Similarly why should potential have anything to do with it when describing the development of a human before it can live independently?  Again, can it truly be argued that a baby can live "independently"?  While there isn't the same direct physically biological link, it would be a stretch to argue how much "independence" is actually involved.

    Basically these questions don't seem particularly scientific, and seem to be arranged around supporting whatever belief system someone has for whatever social/political rationalization one wants to entertain.

    As I said, all the various definitions seem to hinge on particular aspects of other definitions, such as what constitutes a person, versus what constitutes a legal entity, etc.  Regardless of the importance people may place on those distinctions, they are not scientific questions, but perhaps would be more appropriately handled by philosophy.
    Mundus vult decipi
    He's doing what clever writers do; creating a hook to make some points he wants to make.   Obviously as a biologist he is aware that the sociology issues in his piece are too subjective to tackle scientifically.    Hey, he didn't put Lady Gaga in the title.
    IIRC, early embryos may divide to become two *and* later fuse to become one again, so that even under assumption of no embryo or cell line deaths, there fails to exist a necessary one-to-one mapping between fertilized eggs and born individuals. Imo this flies in the face of common sense convention implied by the question "When does human life begin?", and as an answer puts fecundation in the same league as first contact between future parents.

    Thank you for a thought-provoking post. Like you, I do not know when human life begins, but neither do I think the determination belongs within the realm of science. As Gerhard mentioned, this is more properly a philisophical problem to be dealt with by each according to his or her beliefs. That being said, I'm not taking any chances.
    Laura and Gerhard,I think this is definitely a philosophical question, not something we can prove with science. However, perhaps where we diverge a bit, I think scientists, particularly stem cell scientists should be giving some serious thought to this question and discussing it together--hence my post. In addition, policy makers who oppose or favor ES cell research, absolutely should be giving deep thought to this and joining the discussion.

    Too often what seems to happen in the stem cell "universe" is that people fight over positions on these issues rather than actually sit down and ponder the big questions. 

    Stem cell technology  has the power to transform our world for good (potentially saving and improving the quality of millions of lives) and bad (e.g. reproductive human cloning is coming inevitably and there's not much any of us can do to stop it). The scientists driving the field need to pause at times and be philosophers, in my opinion.  The same kind of thing happened with nuclear weapons/energy technology development.  The scientists in the Manhattan Project were very worried about the long-term impact of the technology they were developing and some even were horrified by what happened when the bombs were dropped on Japan and became pacifists, although my great uncle, who was involved in the project, said most believed that the bombs saved a tremendous amount of lives overall by ending the war earlier.
    Paul S. Knoepfler, Ph.D. Associate Professor UC Davis School of Medicine http://www.ipscell.com
    Gerhard Adam
    I agree, however where I have the problem is that it seems that people want to rephrase the "science" to support their particular philosophical position.  Therefore if one supports abortion or stem cell research, then it often becomes convenient to argue that human life begins much later.

    Admittedly there are social and philosophical issues involved regarding the legal status of the embryo (consider murder cases, etc.).  This becomes even more problematic if we were to extend "rights" to the fetus, does that hold the pregnant mother culpable if she does anything to endanger it?  In my view, these are absurd positions, because until a child is actually born, it cannot be said to qualify as a legal individual with "rights".  That also means that there shouldn't be a legal position where a fetus is considered "murdered" (as in the Scott Wilson case).  There's no problem coming up with a new classification of a crime, but it simply muddies the water when we try to fit our ideas of "justice" into this kind of situation.
    I think this is definitely a philosophical question, not something we can prove with science.
    I think the science has already answered the question, so what remains is how we deal with this knowledge philosophically.  If you were provided a cell to test and told it came from an embryo, you may well be able to determine what species it came from and there would be little ambiguity in that assessment.  In other words, it isn't likely that you would confuse a human with a horse, or a dog.  Even if you couldn't determine exactly what the species was, you could confidently wait for the organism to develop and be equally confident that the result would not be random, but quite predictable based on the genetics.  Therefore we know what constitutes the beginning of a human life, just as we know what constitutes the beginning of every other creature. 

    Equally we need to be careful that we don't use philosophical words, like "person", when describing what is taking place biologically.  Biology can establish that an organism is human, but the definition of a person requires something more philosophical.

    I agree that these discussions are philosophical in nature, but that also means that most scientist's opinions on these topics are no more qualified than anyone else. 
    Mundus vult decipi
    Bonny Bonobo alias Brat
    I think this is definitely a philosophical question, not something we can prove with science. However, perhaps where we diverge a bit, I think scientists, particularly stem cell scientists should be giving some serious thought to this question and discussing it together--hence my post. In addition, policy makers who oppose or favor ES cell research, absolutely should be giving deep thought to this and joining the discussion.
    I think that it is interesting that when I was doing IVF 20 years ago and I looked at my son as a raspberry shaped, 5 celled I think or was it 8 celled embryo under the microscope, just before he was sucked into a straw and placed in my womb via my cervix, to be eventually born a healthy baby 8 months later, I had already developed a strong psychological bond with him after seeing him like this as an embryo. 

    This might well have been a result of the quite physically and psychologically arduous and recent IVF experiences of multiple bi-daily injections done by my heavy handed, inexperienced husband and regular early morning hospital ultrasound scans of my ovaries, to monitor the gradual development of the thirty ovarian follicles. This was then followed by egg removal  by a needle inserted via my vagina and the eventual delight of seeing the number '30' written on my hand in felt pen, as I came around from the happy drug anaesthetic and its embarrassment saving oblivion. 

    The number '30' meant that the doctor had quite expertly managed to retrieve all 30 eggs from the follicles, after much stabbing at the ovaries, although it also meant that unfortunately it left me with painful scarred ovaries during ovulation ever since. I think that nowadays this level of super-ovulation is not permitted and the follicles are kept to a much smaller number but I might be wrong.

    If the doctor had tripped by the microscope and gone 'whoops' and dropped the slide and its contents on the floor at that point, I would have probably burst into tears and become quite upset, grabbed the straw and started scrabbling around on the floor looking for the pool of liquid. As it was I was quite concerned that the doctor was heating up the embryo under the strong white microscope light, especially as I didn't even really want to look at the embryo at all.

    To the doctor it was just another interesting embryo that he had helped to create, to me it was a potential and much longed for baby. He was excited but realistic about the embryo, I on the other hand was emotionally involved and had already psychologically bonded with it as my future child. 

    Regardless of all this though, I am a keen supporter of stem cell research and technology and would probably have donated any unwanted and/or discarded frozen embryos at this stage of their development, if I had been asked, which I wasn't, because of the amazing potential that they have to help alleviate fully sentient human suffering and disease. 

    The point I am trying to make is that some people are always going to see even a five celled embryo as a human being that really matters to them, so I imagine that unfortunately there will always be these ethical and philosophical concerns about whether or not these early embryos can and should be utilised for stem cell research and treatments, which hopefully stem cell research scientists will try to understand.
    My article about researchers identifying a potential blue green algae cause & L-Serine treatment for Lou Gehrig's ALS, MND, Parkinsons & Alzheimers is at http://www.science20.com/forums/medicine
    Hi Helen,Thanks for sharing your story and perspective. It is very enlightening.  I think it illustrates the point that everything depends on one's perspective and there is no one "correct" perspective while all others are wrong.

    Paul S. Knoepfler, Ph.D. Associate Professor UC Davis School of Medicine http://www.ipscell.com
    I appreciate the honesty and thoroughness of your post. I believe that conception is the best option for deciding when to treat it as life, and I detailed my reasons here:
    Short version: Conception is the most dramatic, most clear dividing line marking a fundamental change. Your seed analogy is flawed. Viability is an artificial construct to try to muddy the waters.

    I've been considering this question for a long while, and while I certainly don't have any approaching your credentials on the subject, I just think there's a clear answer that life itself is trying to give us, outside of the emotional issues. Thanks.

    Hi Doug,Thanks for sharing your thoughts.  I respect that people will disagree on this issue and understand you do not agree with me. One "benefit" of being a scientist, if you want to call it a benefit is that we get very used to people challenging and strongly criticizing our ideas. 
    Anyhow, one challenge is that this issue is both incredibly important, one of the biggest questions one can ever ponder, but also it is one that is not something that ever can be proven.  
    There are tremendous implications for this question that essentially require laws be passed based on the answer, but how do we do that when even just Americans (let alone people of diverse cultures around the world) cannot even remotely agree upon the answer?
    Paul S. Knoepfler, Ph.D. Associate Professor UC Davis School of Medicine http://www.ipscell.com
    Something doesn't need to be proven beyond a shadow of a doubt, and accepted by the entire planet, before laws can be enacted. Heck, ask any economist. :) But with something as important as life (and death), we as a culture and nation need to agree on something so as to protect life in general. (We don't need to agree as a world; we don't make their rules.)

    Indeed we can't all agree on it, but then we can't agree on what economic policy will get us out of this recession, either. So, do nothing? Sit and ponder for a generation? Again, this is an even more important issue, one in which government has been given specific power to protect life, liberty and such. Protection of the weakest among us is certainly something the government should have a hand in.

    My concern has always been, especially with regards to abortion (which, after all, is one of the main political areas this question applies to), how does this affect where we as a nation agree to allow abortions? Do we value life, or at least do we respect the science that shows such a dramatic line at conception? If so, knowing what we then know, where is this pressure to use the artificial construct of "viability" to even enter the equation? (And my answer, of course, are those that stand to make a profit from abortion; never mind the cultural desensitization.) The problem with this, IVF, cloning, and all manner of tinkering with the life process is, if we don't stop to at least come up with some baseline of what life is and how we should treat it, this sort of research and practice go on in a moral and ethical vacuum.

    If it's so important (and it is), why leave it as something our minds work on in the background while experiments and procedures upon which it would have a substantial impact continue on without being informed by the answer?

    The personhood question is, I agree, a separate issue, and one you can't really fully deal with until the "lifehood" question is dealt with. Life and Death, or perhaps Life and Not-Life.

    To be or not to be. That *is* the question, actually. It needs, nay demands, an answer. And life itself is, I believe, trying to tell us that answer.

    Gerhard Adam
    Do we value life, or at least do we respect the science that shows such a dramatic line at conception?
    I think that's a red herring.  Our actions as societies indicate that we aren't particularly concerned about life and we pretty much assume that every individual has to fend for themselves.  Even the idea of laws isn't based on protection as much as it is based on maintaining social order and determining what recourse the state has in maintaining that order.

    You may think I'm being cynical, but it is all well and good to be concerned about a fetus, but can any society claim to value life if it maintains a death penalty?  Engages in war for anything except defense of their home nation?  Doesn't ensure affordable health care, food, living conditions, etc?

    I'm not advocating that these things need to be done or not, but rather pointing out that this is precisely where a discussion regarding the "value of life" must turn.  If not, then to discuss it only within the context of beginnings is disingenuous.  This is precisely why one of the primary criticisms of the "right to life" people has been that they're all concerned about a fetus being born, and not so keen on how they actually have to live their lives after birth.
    Mundus vult decipi
    Gerhard Adam
    The personhood question is, I agree, a separate issue...
    That's the ONLY issue, since it is the basis by which laws may or may not be created.  Without personhood, there is no concept of rights.  Without rights, there is no basis for political involvement in passing laws. 

    People that want to bog this down in issues of life are missing the point.  Science already knows the answer to that question.  The question that society needs to address is when such a living thing attains the status of a person for whom societal/political protections and participation apply.  Viability and potential are not criteria for establishing "personhood".  Similarly, we tend to dodge the question even when it comes to children and what constitutes their "rights".  Until we seriously address these points, it will simply be a matter of personal belief or opinion.
    Mundus vult decipi
    Gerhard Adam
    I'm not sure you've actually formulated a question.  You certainly do know when human life begins, although you can't know when "a life" (i.e. a person) begins.  The problem here is that the philosophical issues are being conjoined with the scientific ones, and science is definitely not ambiguous about this. 

    It is foolish to argue whether a few collections of cells are alive, because we know they are.  It is equally foolish to question whether they are human, since we know they are (as I stated before, they will not develop into some random organism).  Therefore once there are an operational set of genes and the cells are growing and dividing, it would be an unusual feat of mental gymnastics to claim that this organism isn't alive.

    The philosophical questions are something different, because it relates to the concept of "personhood" and all its attendant social and legal implications.  That is what the laws will be based on, so let's not muddy the water about whether something is alive.  We need to focus on determining when an organism acquires a status that allows it to be incorporated into the larger social group.   Does that begin at conception, or after birth?  At present, the law seems to consider the fetus a person only if the mother accepts it as such.
    Mundus vult decipi
    Just thought you might like to read something that is amazing and quite real regarding parthenogenesis.
    Go to: www.thestoryoflaurie.blogspot.com I would like very much to have your feedback. Thank you.