Pre-natal Parent-Offspring Conflict: Human pathologies explained by Ev. theory

A fascinating article in the NY Times illustrates beautifully how evolutionary theory can help explain the ”why’ of apparently anomalous and otherwise unexplained biological phenomena including the origins of specific human medical problems. (Oh that any alternative to evolutionary theory could prove so useful!). You can find the complete article here In 1970 Dr. Robert Trivers put forward his rather controversial theory of Parent-Offspring Conflict. Essentially, he pointed out that, from a Darwinian ”selfish genotype’ standpoint, offpsring should be selected to demand from their parents more resources than it is in the parents' best interest to provide. An ornithologist by training, he pointed out that this effect leads mother birds to drive fledged chicks from the nest and deny them food once they are capable of fending for themselves. The effect is most simply explained by the fact that the fitness functions of parent and offspring are not identical. It is in the offspring’s best interest to extract the maximum resources possible from the parent (little parasites !), while it is in the parents' best interest to successfully raise the largest *number* of offspring possible and, at some point, this means limiting the resources they provide to each individual offspring.Recently, a Harvard evolutionary biologist has extended Triver’s theory to pre-natal conflicts and the inferences are currently being borne out by a plethora of genetic evidence that molecular biologists were at a loss to explain without the insight of this evolutionary reasoning. The implications are proving useful in understanding the root cause of many of the complications of pregnancy suffered by mammalian mothers.For those averse to news subscriptions, here are some excerpts from the article: So I would like to know how creationists might explain this remarkable coincidence between evolutionary theory and previously unexplained medical conditions. Do they have an alternative explanataion? Better still, how do ID proponents explain the 'design' of such an apparently conflicted biological system?Biological Evolution seems the most appropriate venue for this topic.Have fun, EZ.[edited for typos]This message has been edited by EZscience, 03-16-2006 08:11 PM

Holmes, I am always impressed at how effectively you can defend the other side's point of view without actually subscribing to it. Don't you think if you were going to 'design' or 'create' something as biologically complex as pregnancy (internal fertilization followed by gestation) you would do so without designing into it conflict and antagonism between mother and child before birth? It seems a good designer or creator could do a lot better. It goes a lot deeper than that. What about the parental gene conflict within the developing fetus, the mother's genetics essentially battling the father's genetics and trying trying to turn off paternal genes that are trying to extract more resources from the mother? Don't tell me that is a simple extension of economics theory - it has to do with differntial genetic representation in the offspring and disparate fitness functions between mother and father. And don't pretend that creation or ID theory could have predicted such effects 'a priori' before the molecular evidence was produced to support it. Not buying it, sorry.And many good scientific insights have exactly that quality you complain of - they tend to be true no matter who comes up with them, and infuriatingly obvious once revealed. 1. because the inherent conflict and antagonism they entail that seems to contradict the inherent 'perfection' implied by ID and creation.2. because ToE predicted what was observed BEFORE it was observed - what in ID or creation 'theory' could possibly have predicted the existence of this type of conflict? That is pretty much natural selection you are describing. Many characters and mechanisms are tolerated that may be less than optimal, or represent some sort of compromise, but their predominance and persistence in a population implies that they were selectively adavatageous *relative to alternatives*. But on a larger (population) scale (larger than a few dozen mice in an experiment) this type of conflict *does* lead to serious problems for some individuals. The differences measured in the experiment merely point out the function of the genes. The whole point is that many, many pregancy complications stem from this conflict and that mother and offspring DO lose their lives in some cases because of them. This has nothing to do with species extinction or the end of the human race. It is hard to explain complex scientific inferences effectively in popular articles. I assist journalists from time to time trying to write publicly accessible articles explaining the results of our research. It's not easy, believe me, and I am not always pleased with the results. But this is an example of sound evolutionary reasoning that not only explains otherwise puzzling observations, but also helps us understand and anticipate other physiological and behavioral consdequences of genomic imprinting. I also disagree in that I think all this makes sense ONLY in the context of evolutionary reasoning. Taken out of context the way you are doing, perhaps. But you ignore the whole body of scientific observations in various fields that people were having great difficulty explaining before these inferences were made. It is 'robust' in the sense that many different lines of empirical evidence all seem to fit very well. You have touched on a very salient point here. What is implied is a form of group selection or kin selection effect, and we recognize these types of selection only when they run counter to selfishness - otherwise simple individual fitness is an adequate explanation of behavior. But the evolution of altruism could be a whole new thread topic. No, I think that this would prove a very flawed line of argument. Neither ID nor creationsism made any a priori predictions regarding the observed phenomena and neither appear very compatible with their existence. Not at all. But as you are someone who believes in evolution, I do find your frustration puzzling. This may be a somewhat superficial piece of journalism, but it's is definitively NOT bad science. The scientific reasoning is sound and the insights are proving to have value to medicine. When have ID or creationism *ever* provided insights useful to understanding medical phenomena? I don't think I even need to answer that.

I think you have stated your position in detail and I don’t want to belabor too many points on which we apparently have entrenched positions, but I have to take issue with some. You apparently see this as a poor application of evolutionary theory, and a poor attempt to popularize science. I see it as a good application of evolutionary theory, albeit a superficial article.And NWR, just because so many popular science articles are necessarily superficial and often fail to do justice to scientific topics doesn't mean we should discourage the popularization of science. We need to try and help journalists do bettter, and help the public understand more about science. We can't just throw up our hands and say to heck with it. I don’t think the science is bad. Incomplete and preliminary certainly, but not ”errant’. You have correctly pointed out that the inferences presented do not exclude alternative explanations, but you haven’t presented any evidence to suggest they are errant, nor a more constructive way of viewing the conflict. I know from previous posts your position on the application of evolutionary thinking to behavior and psychology, and yes, there are some poor and speculative applications out there, but that does not mean we should not seek careful ways to extrapolate evolutionary thinking to these disciplines. There are still plenty of incorrect hypotheses to be weeded out but I don’t think this is one of them. Elimination of incorrect hypotheses is part of the scientific process and we don’t have a better framework than ToE for examining the underlying causes of biological phenomena. Fine. But why ”design’ a conflict? Maternal genes turning off paternal genes, and paternal genes modifying the expression of maternal genes within the developing offspring? You don’t see that as a genetic form of aggression ? The point here is only to demonstrate the functions of these particular genes not to imply a cascade of consequences beyond what was observed. The mother wants to partition resources to maximize her fitness and this includes raising other litters. Paternal interests only extend as far as the current litter, hence paternal genes exist that atttempt to extract more resources for the current litter than it is in the mother’s best interest to give. Since so few such genes have been identified and studied to date, it suggests that many other genes may exist that act to further the interests of one parent over that of the other in the fetus. You don’t find that interesting and worthy of further investigation? Come on holmes, the prediction was BASED on evolutionary reasoning, reasoning that gave rise to a series of inferences that are proving consistent with diverse genetic observations from different fields of medicine. If you read Triver’s original article on parent-offspring conflict published in 1970 you will see how this is a really a good extrapolation of his hypotheses. (The only serious shortcoming of Triver’s original hypothesis was an assumption of equal parental care resources in male and female.) They couldn’t have because they do not have any mechanistic framework for predicting or expecting to observe anything - by their own admission in most cases. We are going in circles here. I accept neutralism, and a lack of selection against something doesn’t equate to selection for something, but a lack of selection against something isn’t going to make it the rule rather than the exception when alternatives exist. I wouldn’t descend to term either ID or Creo’ism ”theories’ in the scientific sence because neither produce testable hypotheses. By extension, they make no meaningful predictions about anything. Here is an example of ToE making predictions that are slowly being borne out by new sources of evidence. Just because the evidence is scant to date is no reason not to seek more of it or to try and smear the effort as bad science. Why? Thinking beyond the current evidence is the best way to figure out where to find more and better evidence. You can’t seriously liken that to propagandizing for political purposes. You seem to have a very cynical and jaded perception of what motivates scientists. The point is there is reason to suspect many - and therefore reason to look for more evidence of the same sort to help understand other unsolved pregancy complications. Not at all - it is simply an outcome of competing genetic interests between mother and father. There is no suggestion that the ”system’ (of conflict) has any adaptive value to individuals or groups. So no, you are wrong here. The point is, in the vast majority of ”normal’ pregnancies a genetic ”truce’ is reached within the fetus and there is no apparent evidence of any conflict. But the conflict lays a foundation of inherent instability and problems can arise when things go wrong, as they inevitably will in some cases. Yes to the first - a categorical no to the second. I will go out on a limb here and venture that you probably are not a research scientist yourself or you would see just how potentially powerful and useful these insights are. They tell us we need more efforts to identify paternal genes that produce products selectively targeting the expression of maternal genes and vice versa if we want to better understand the molecular basis of a lot of pregancy complications. That’s what we should find if we look for them. Time will tell if further evidence accumulates or not, but there is every reason to expect it will. Unless you have a reason to expect otherwise? You have a far too narrow definition of evolutionary reasoning. The evolutionary *origins* of these phenomena are not the point. It is an understanding evolutionary *process* - how evolution can be expected to shape things - that gives us the insights. And BTW, game theory has been an integral part of evolutionary reasoning ever since Maynard Smith’s seminal paper on the application of game theory to evolution of behavior in the mid 1960’s. ID and Creationism are useless for this because they posit no mechanistic processes - Evolution does. Evol. Theory tells us why to expect conflict between mothers and fathers when it comes to investing in offspring. Neither ID nor Creo’ism have ever made use of game theory to explain anything. Evol. biologists have. It doesn’t only ”fit’ - it offers a logical explanation and points to specific avenues of empirical research. You can’t seem to grasp this. Holmes, I think you are doing science a great disservice here. ToE isn’t being used as arbitrarily as you claim. No simple assertions are being made. Rather, inferences from evol theory about how the system should be expected to perform are proving useful to help us determine what sorts of genetic interactions we should be looking for. How could ID theory tell us, a priori, to start looking for exclusively paternal genes that try and amplify the transcription of particular maternal genes? Because few doctors in medical research are thinking in evolutionary terms. It took an evolutionary biologist to point them in the right direction. No one else did. That was my point with the OP. Creation scientists didn't suggest these interactions might exist - and neither did ID - although by their very nature they can be made consistent with almost anything after the fact.This message has been edited by EZscience, 03-19-2006 12:17 PM

I wasn’t trying to boost the article, I found the concepts discussed interesting, consistent with evolutionary theory, and a potentially useful extension of it. Time will tell, I suppose, if this proves to be the case or not. If it doesn’t pose a ”problem’ for ID, it at least illustrates how constructive use can be made of evolutionary reasoning to address practical biological problems. I continue to hold that there is no such parallel applicability in ID. There is no framework to help anyone think in useful ways about how the world works. I disagree. No other line of reasoning led to these inferences. It was thinking about how indivdual fitness interests compete on a genetic level that led to the insights - not how they might have been designed to compete. You have no evidence for this. None. It is far more likely to my mind that evolutionary reasoning had never been specifically applied to this particular topic. Accepting for a moment your analogy, there is a serious problem with extrapolating it to the situation at hand. This is not a system that has evolved because it is the best way to allocate resources to offspring. It has evolved as a compromise that reflects competing genetic interests of the parents. It reflects selection acting differentially on maternal and paternal strategies at a genetic level that has resulted in this compromise. The ”system’ is not under selection itself - it is simply an imperfect consequence of selection acting differentially on individuals of opposite sexes - something ID gives us no framework for understanding or reason to expect. I hope you realize you are making a group-selectionist argument here, when selection acting at the level of individuals is entirely sufficent to explain the phenomena.
The ”system’ is a consequence of selection on individuals - there is no reason to believe it is under selection itself as your analogy implies. Maybe this is just a bit of hasty writing, but your use of the word “intention” seem inappropriate. Evolutionary changes have no intent, nor do mutations. I would also contend that the situation is not so much ”a part’ of our genetic system (in the integral sense) as it is a consequence of it. Besides, don’t you believe in passive aggression? Sorry - sex determination has nothing to do with genomic imprinting. Completely different genetic mechanisms are involved. Even if sex determination were environmental, that should have no effect on the phenomenon under discussion. Theoretically, the only prerequistes should be (1) iteroparity (multiple reproductive events for each individual) and (2) internal fertilization with extended gestation, the latter implying disproportionately high pre-natal investment by the mother. If you want to argue this you need to provide a convincing line of reasoning that arrives at the same a priori conclusions WITHOUT any evolutionary inferences. You can’t do it without using evolution because selective forces acting differentially on individuals of opposite sexes, as predicted by evolutionary theory, are the reason we expect to see maternal-paternal competition for directing resource allocation within the fetus. No other ”theory’ gives us a priori reasons for expecting this. Your argument that this ”system’ could just be the most effective means to the end, regardless of how it came to be that way, falls flat on its face because it hinges (erroneously) on the assumption that the ”system’ is what is under selection when that is not the case, as I have explained above. In fact, I would predict that with the appropriate molecular tests we could probably measure ”costs’ of this genetic competition that are probably shared, equally or unequally, between both sexes, making this conflict inherently sub-optimal. It has simply evolved as a rather inefficient compromise between competing parental interests. Well the evidence is just beginning to be collected, but I am starting to doubt whether you truly understand the mechanism. There are a lot of implicit assumptions in your scenario that are highly unlikely.
Even if your gene was dominant (red hair is recessive, so bad example), it would have to be tightly linked to the resistance gene to piggy-back on its selective advantage. Any reason to expect why that might be the case ? Ever hear of independent segregation? The tendency is for all gene associations to be broken apart every generation. Linkage disequilibria (long considered evidence of gene linkage on chromosomes) have turned out to be quite rare. No, predominantly expressed traits in a population are usually those optimal under prevailing conditions. Various neutral traits may be equally frequent as one another, or may *temporarily* rise to high frequency through bottlenecks and founder events (such as your analogy approximates) but they cannot be *sustained* at high frequency without confering selective advantage. But this is an OT digression. It would be nice to see one concrete example of how ID has provided insights for anything useful in applied biology. Haven’t seen one yet. And your example of their use of ”reverse-engineering’ is actually just a ”reverse-engineered’ version of evolutionary engineering - where technologists have developed self-correcting algorithoms to ”evolve’ optimal designs for things like multiple airfoil wings. If you don’t, you are never going to design a novel experiment or develop a novel concept. Holmes you are flogging a dead horse. I already explained that this experiment was only to verify the function of a particular gene specific to the father in this instance. You are trying to equate it as some sort of a test of the full range of medical implications of the theory, which it isn’t. It is merely an indication that paternally derived genes *can* target specific maternal genes controlling resource allocation to the fetus and that, in this particular case, their function is to amplify the products. Your criticism is totally mis-directed. I have done this in a dozen different ways now. Sorry, the burden of evidence is yours to show why any ID interpretation *would* predict it. I have better things to do than to work out why pseudoscience is unable to replicate real science. Perhaps you are not fully appreciating the unique nature of the genetic mechanisms that are emerging. The links to evolutionary processes appear very obvious to me and I don’t see any better interpretations being put forward. You certainly haven’t put any forward - all you have done is challenge me to do your job for you. They didn’t though, did they? Their dogma is so tautological that they can make anything fit their interpretations *after the fact*. You still haven’t explained what in ID would predict any of these types of conflicts a priori - and to top it off you want me to engage in that futile exercise in reverse.It doesn’t have a lot to do with ID but it has everything to do with how useful evo theory can be when it comes to predicting how living things work and interact. At this point, I am at a loss to explain your failure to grasp the link to evolutionary thinking, so I give up. You can claim it would have been discovered some other way - but it wasn’t. You can claim other lines of reasoning *might* have predicted it - but they didn’t. And you certainly haven’t produced a shred of evidence to suggest how thinking in ID terms would have predicted any such phenomenon, although you repeatedly demand I do the reverse. What planet are you living on!! Most MD’s I meet wouldn’t even know who Haldane or Fisher were. The only continuing education they seem to get around here after graduation is in the form of brochures from the pharmaceutical industry. Your generosity astounds me. Yes, but they used established scientific reasoning and procedures to make these advances - their reasoning wasn’t directed by their religious convictions, even if they felt they were ”doing God’s work’. Religion might have motivated them or been inspiring to them, but it didn’t guide their reasoning or their discoveries. Good science theory did.Take your time - I got a half day off because of the weather here.

I need some time to reply to this. Just had a few things hit my desk that will swamp me for the rest of the week.Nice find on the articles. I'll try and examine them more closely this weekend and come back with some comments.

I think this is an important distinction.
Because literal belief in the bible or any other sacred text is a subscription to something as an absolute truth, it is not really a theory at all, e.g. There is no need to work out any functional mechanisms for anything, nor is there any framework provided for doing so. It just 'is' that way because God said so.In contrast, scientific theories seek actual mechanisms of how things work or how they have come to be as they are. They may not be more true, but they are certainly more useful.
It is pretty much assumed they are imperfect, but they are designed so that imperfections can be detected and their structure modified through continued observation and experimentation.
A lot of 'theistic evolutionists' are quite happy to see evolution as a mechanism of creation, something set in motion by God, but not necesssarily micro-managed by him. This view prevents their beliefs from interfering with their ability to advance and test actual theories. Fine. But where is the explanatory power? It seems simply a cofirmation of what is obviously known to be true.In my mind, I am not so much interested in the absolute truths that religions seem to concern themselves with as I am in useful ways of figuring our how living things work and interact. So I don't take issue with whether or not the above statement is 'true' (God made women suffer after the Fall, whereas they didn't before), I just don't view it as a very useful premise from which to advance our understanding of the mechanisms involved in the genetic conflicts apparently occuring between a fetus and its mother.In contrast, ToE predicts differential levels of competition between individuals in proportion to their degree of relatedness, all in the interest of individuals promoting their genetic representation in the next generation. This is borne out pretty well by observation and can be useful for anticipating various types of interactions among individuals, and in this case, among genes within individuals. That's pretty much what a creationist is.

OK Ned,I meant Redeemed appeared to be a 'creationist' in the broader sense - not specifically a YEC literalist - but one who believes in an omniscient 'creator' of the universe, and likely holds a teleological world view that follows from this belief, although I'm speculating here.

I would contend that you haven't shown any superior inferences are derivable from any alternative interpretation of the observations (other than evo). I continue to claim that the evolutionary perspective is the most useful framework for thinking about how imprinting came to be and what its potential consequences are. I don’t see ID reasoning being useful for either. I don’t entirely agree. Relatively old ideas implied genetic conflict on various levels, right down to different genes jockeying for the best positions on a chromosome. That evo theoy had not until recently been applied to conflicts between genes arising from different *parents* doesn’t mean much. The theory continues to be refined and ”evolve’. At least it has a working framework capable of recognizing errors of omission which is more than can be said of ID. This doesn’t necessarily follow. I think it’s a bit of a stretch to infer that ”traditonally viewed’ can be construed to mean an evolutionary perspective was already being applied. I don’t think you have shown this. All you have done is superimpose a possible ID interpretation on the results an imply that evolutionary theory was previously mis-applied. Maybe it was, or maybe nobody had thought to applying it in this way. We can be thankful that evolutionary theory, being an actual scientific approach, is capable of modification and refinement. Theories go out on a limb sometimes because they makes actual predictions about what we can expect to observe. I don’t seen any testeable predictions emerging from your contrived ID interpretation. I say they CAN’T - they don’t make any testable predictions. You are just showing they can be shoe-horned to fit any set of observations after the fact. Who said it was the only theory? It is simply a previously unstated hypothesis that seems to be a better fit to the data (and have more explanatory power) than any other model that anyone has thought of yet. You can argue in retrospect that it is now obvious that that is how things should work regardless of what model of nature one subscribes to, but the fact remains that the evolutionary perspective produced the insights and will work best for modifying and improving our understanding of these mechanisms over time. Actually, PO conflict theory was developed to apply to kinship, not ”social settings’ per se. Again, I think you are working with a rather narrow definition of what evolutionary theory comprises. Genetic conflicts can be predicted by evolutionary theory in many different contexts. I don't think it's a problem. It only indicates that invasive placentation is not a prerequisite for imprinting to evolve, since marsupials such as opossums also show imprinted genes, whereas egg-laying mammals do not. To my mind this merely discounts the role of the placenta as being essential to selection for imprinting. However, recall that marsupial young are born extremely altricial - there is a very extended period of maternal dependency even if it occurs outside the mother’s body in a pouch (not sure that is even technically 'outside'). The key factor here is the high level of physiological maternal investment, regardless of whether it involves a placenta or not. This is considerably reduced for montremes that merely lay eggs.