The P-Value Podcast
The P-Value Podcast
The Metaphysics of Pregnancy
A bun in the oven? Eating for two? So many of our common phrases regarding pregnancy presume that pregnancy involves two distinct entities —the foetus and the maternal organism in which it resides. This sort of “container model’ of pregnancy pervades so much of our everyday discourse around pregnancy and in the academic sphere. Philosophical discussions of the ethics of maternal behaviour, for example, frequently claim that the location of a child, whether it be within the uterus, or outside is irrelevant to its ethical status. Socially, the tendency to see pregnant women as parents, with all the responsibilities that carries with it, even before they give birth is common. How justified is this view though? Does it have the sort of biological or scientific basis we might assume it to have?
Follow up references:
https://bump.group/
https://philpapers.org/rec/CLATPO-15
https://philpapers.org/rec/CLATMR-2
A bun in the oven? Eating for two? So many of our common phrases regarding pregnancy presume that pregnancy involves two distinct entities —the foetus and the maternal organism in which it resides. This sort of “container model’ of pregnancy pervades so much of our everyday discourse around pregnancy and in the academic sphere. Philosophical discussions of the ethics of maternal behaviour, for example, frequently claim that the location of a child, whether it be within the uterus, or outside is irrelevant to its ethical status. Socially, the tendency to see pregnant women as parents, with all the responsibilities that carries with it, even before they give birth is common. How justified is this view though? Does it have the sort of biological or scientific basis we might assume it to have?
Recent work by philosophers of science such as Elselijn Kingma, and Fiona Wollard from the Kings College London and University of Southampton and suggests perhaps it doesn’t. Perhaps, they say, an alternative parthood model —in which the fetus is considered part of the maternal organism, just like the maternal organism’s organs and limbs—is more a more accurate account of the metaphysics of pregnancy than the commonly assumed container model. Such a view, they argue is not only plausible, but such plausibility has far-reaching implications.
Today in the P-Value we are talking about the metaphysics of pregnancy.
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Metaphysics—the philosophical study of what exists— is littered with disagreements about the ontological status of objects. Is, for example, a statue the same, or a different thing to the clay from which it was made? What about the pile of broken shards when we smash it? Are they also the same thing? Or different? Is the well-worn ship of Theseus the same ship it was when first built even if all the boards have been gradually replaced over time? Or is it a different ship?
Strikingly, it is only that recently these debates have included discussion of the metaphysical relationship between mothers and their gestating offspring. The focus instead has typically been on the ethical responsibilities of mothers to their offspring with an assumption that their relationship is not one of a part and whole. It may be that this is because the answer to the question of where the maternal organism ends and fetus starts has been considered obvious—the maternal organism and fetus are different entities, the fetus just happens to exist inside the maternal organism for a time—or perhaps it is because the sort of people that have traditionally done Western analytic metaphysics—white men—have had little intimate experience with pregnancy beyond their own long forgotten birth. It’s hard to say, but over the past decade a thread of work in philosophy of science, bioethics and metaphysics has begun unpicking these issues to try to give a well-reasoned answer to the question: Were you ever a part of your mother? Or always something else?
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One place we might naturally look to try to determine whether the parthood or container models of motherhood are most appropriate, is the philosophy of biology. In that discipline, there is a long tradition of thinking about the nature of biological individuality. What is, it is asked, the difference between growth and reproduction? When does one organism, become two and when are we merely witnessing growth, excretion, or some other bodily function? Why is the birth of a baby the origination of a new individual, when losing a tooth is not?
Within that literature numerous criteria have been put forward to try to resolve the question of how to delineate between organisms and their offspring, ranging from genetic heterogeneity, to the presence of a single-celled stage or bottleneck, to physical disconnection, and functional integration. Given that humans are, after all, just a very familiar variety of placental mammal, and surely whatever account we offer of the relationship between maternal organisms and their offspring for our species should apply to others if it is to be objective and scientific and so, it seems reasonable to look here for some sort of criteria to resolve our initial question of whether you were ever part of your mother.
A challenge for this move is that there is no agreement about the metaphysics of biological individuality. We cannot simply read off the biological literature a clear-cut and agreed upon criteria for determining the boundaries between a maternal organism and their offspring. Whilst this much is true, at very least the literature does, to my mind still serve to undermine the dominance of the container view simply because, although it offers a variety of ways of trying to cash out further why we might think of the fetus as being separate whilst contained by the mother, it also offers us reasons to defend the parthood model too. Considering some of the criteria for biological individuality helps illustrate this.
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One very natural means of trying to distinguish between biological individuals is simply to look to their self-containedness or physical separation. When a farmer looks to their field of sheep, they count them by counting bodies. Similarly, the ecologist doing a field survey of black cockatoos, sits and counts bodies. Each physically separate entity is another individual.
Whilst intuitive, this view, actually goes against the container view because fetuses are spatially continuous with their maternal organism. They are connected via the placenta and umbilical cord right into the maternal blood system even if we are tempted to say that they are only within the womb as a container.
Spatial discontinuity is also often set aside in the biological individuality debate more broadly because it produces some counterintuitive results when it comes to individuating organisms in various biological cases. Consider, for example, the quaking aspen—a medium sized deciduous tree species found in north America which grows to up to 30 metres in height. One way they reproduce is by genetic clones sprouting from their roots. This results in large groves of genetic clones which remain connected at the root system and thus, at least on the physical separation criteria, are one biological individual. Pando or trembling giant is the largest of such clonal groves, existing over 100 acres in Southern Utah. At more than 14 million pounds in weight it would be the world’s largest living organism if we count it as a single individual. Quaking aspen are not unusual except perhaps in their size. Many plants reproduce in this way—new strawberries, for example sprout from runners or stolon off the main plant which may, or may not, eventually become physically dethatched. On the physical separateness criteria, a group of strawberry plants are all one biological individual for as long as they have some physical connection, even if that connection is so tenuous that they would all` persist quite happily if I broke that connection.
This strawberry example might make us think we can save the physical connectedness criteria but adding a further condition for individuality to physical discontinuity—that something is a part of whole if they are both physically connected to it and are not capable of independence if they were to be separated. In short, we might point to the potential autonomy or independence of the parts of a biological systema as delineating individuals. On such a further criteria, the individual trees of the quaking aspen, the strawberry plants, and a mature fetus are, unlike say the the claw of a lobster which once thrown cannot persist or a tooth lost which is impotent beyond the body, able to persist and reproduce themselves and thus separate biological individuals even if not entirely spatially disconnected.
Whilst this is appealing it again isn’t without criticism. One may, for example, push against the idea that the autonomy criteria supports a container model for the human fetus and their maternal organisms, because no baby can survive on their own. Indeed, whilst physically disconnected, newborn babies are anything but independent or autonomous from their parents, or at least the intervention of some adults if not related to them. In this sense, one might ask, how different are they to the claw of a lobster which will wither and die once separated from the organism? This criteria seems to push us again towards viewing fetuses as part of their maternal organism.
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You might try to save the container view by looking to a different condition. Perhaps something has to be both physically continuous and genetically homogenous to be a single biological individual? Whilst this would not help us in the case of the strawberry or aspen plants – they would remain one plant each — it does give us some traction to push against the maternal organism and fetus being one biological individual. The fetus and its maternal organism are not genetically homogenous and thus, despite being physically continuous, are not the same biological individual. Unfortunately, whilst this criteria might seem to give motivation for the container model of motherhood, it comes with some other consequences which are so counterintuitive as to think it probably can’t be right. Consider for example, the famous case of Karen Keegan.
Karen Keegan was an everyday woman, or at least thought she was, until she underwent genetic testing along with her family in the hopes seeing if a family member could donate a kidney to her. The result of the tests were a huge shock, however, because, while she had photos of herself with her children as newborns, could remember giving birth etc… the DNA tests suggested she could not be their genetic parent. In short, they didn’t carry her DNA. Had she been their father, the assumption would have been that there had been adultery at play but in the case of Keegan, doctors were flummoxed. How could it be that this woman that remembered giving birth to her children and indeed had photos of them at birth etc… not be their biological parent? Moreover, this couldn’t be a case of the kids being switched at birth either as they did have Karen’s partner’s DNA, he was their father. The apparent paradox was resolved when biologists DNA tested other parts of Karen than just her blood. She had different DNA in her blood cells compared to other tissues of her body. In particular, her oocytes or eggs and ovaries were different genetically to her blood, and this explained why her sons did not share the DNA in her blood. Why this was the case, is that unbeknown to Keegan she was actually one of a pair of fraternal twins. Early in gestation, Keegan’s twin had died, and the cells had been absorbed into the embryo that eventually developed into her. This left her with both the cells and DNA from the original embryo and those of the absorbed twin. She is, what is knows as a chimera. Keegan’s case may seem outlandish but she is not the only reported case and, furthermore, because we don’t routinely genetic test people and their families, there are likely lots more such chimeras around.
Now, to return to the metaphysics of pregnancy, chimera cases like this have our criteria of physical connectedness and genetic homogeneity on shaky ground. Either we have to declare Keegan more than one biological organism—a highly counter intuitive result—or the criteria need revision. You might be tempted to bite the bullet and say that Keegan is two individuals, but such a bullet is bigger than you might think. There are other cases of human chimera that also push on the view. Following a bone marrow transplant, for example, some or even all of the blood cells of the recipient carry the DNA of the donor. On the genetic criteria we have ended up with two biological individuals where we had one before, but it would be odd, I argue, to think of the marrow transplant as being a moment of reproduction. The recipient does not seem to have been cleaved in two in virtue of having had the transplant, but that is what is suggested by the genetic identity criteria. Once again, we appear to be in strife and the attempt to find some sort of principled criteria for the container view falls.
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Thus far we have looked as some reasons why the container model doesn’t seem to quite work but that is no positive reason to go for the parthood model. A positive reason for the parthood model, put forward by Elsejin Kingma is the metabolic unity and functional integration of the maternal organism with the fetus. An organism’s parts normally work together as one metabolic system, she says. They work towards a common goal “the survival and reproduction of the organism”. In this the organs of a complex multicellular organism like a human are, whilst differentiated and diverse, parts of a common whole which has evolved for survival and reproduction. Thus, Kingma says the marker of being part of an organism is functional and metabiolic integration and interdependence on the whole.
Harking back to my earlier suggestion that babies are actually not autonomous from their parents even when born, Kingma says the interdependence being pointed to here is three fold. First, the fetus depends on the maternal organism for many of its metabolic activities including waste disposal and temparture regulation. Second, the fetus is actively integrated into the maternal oragnism’s metabolic system. When an organism becomes pregnant, changes are made to cardiact output, blood volume etc… and adjusted over the entire course of gestation. Last, the fetus and the maternal organism work together to achieve a common goal of survival and reproduction. In this sense, it is claimed the fetus is best understood as part of the maternal organism, not simply contained by it.
There are some objections to this view. There are, for example, conflicts between the interests of the fetus and those of the maternal organism. The fetus for example typically remains within the maternal organism longer than is required for mere viability outside the womb to grow as big as it can before facing the world outside. This arguably continues longer than is in the interests of the maternal organism, the risk of complications increasing as the baby grows. Kingma argues that whilst these conflicts exist, they are rarely of a serious nature as the helplessness of human infants means that their survival interests align strongly with that of their maternal organism, even if at times there is not a complete overlap.
Another reason Kingma puts forward for parthood also draws on biology. Specifically, an immunological account of individuality often associated with French philosopher of biology Thomas Pradeu from the University of Bordeau. Pradeu argues we can use immunological tolerance to delineate organisms—Keegan is one organism because there is immunological tolerance, In other words there is recognition of even the formerly twin parts of herself, as “self” by her immune system. Similarly, says Kingma, the maternal organism does not reject the fetus. It is not attacked and treated (at least in most circumstances — I’m thinking of things like blood incompatabilities here as cases where this fails to be true) as self by the maternal organism’s immune system. One might argue that this is only achieved by both a dampening of the immune system during pregnancy and some sort of “shielding” of the fetus from the maternal immune system rather than true parthood. Kingma responds to this worry by pointing out that not all those elements we typically take to be part of an organism, such as the brain, are fully integrated into the immune system either. For example, the blood-brain barrier protects the brain from inflammation by stopping many immune cells and agents from getting into brain tissue. This doesn’t stop us from thinking of the brain as being part of the organism, says Kingma, and so, we shouldn’t reject the fetus being part of the maternal organism either. What do you think?
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Physical discontinuity, genetic homogeneity, integration, autonomy, immunological identity. These all offer different criteria of carving up the world into biological individuals and see us drawing different boundaries when it comes to the maternal organism and the fetus. There are other options available to us, but I will stop there suffice to say that none is entirely satisfactory in that none seem to hit the sweet spot between capturing our intuitions and scientific interests in talking about biological individuality, without having unintuitive or unappealing consequences.
Given the lack of a single entirely satisfying definition, we might well throw our hands up and say there is no fact of the matter to be had here—there are no facts about biological individuality and at least in so far as we thought biology might help us with the metaphysics of pregnancy it cannot. What do you think? Are you a pessimist? Or an optimist? I’ve put some links in the episode notes to references if you want to follow up more.
That’s all for this ep, see you next time.
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Thank you for listening to the P-value. The P-Value podcast is an initiative of the Centre for Philosophy of the Sciences at the Australian National University.
