When evolutionary-minded medicine gets it (possibly) wrong about childbirth interventions

No one is saying that medicine isn't brilliant and hasn't saved lives. But it does intervene more than necessary when it comes to pregnancy and childbirth.

Part of that unnecessary intervention is driven by lack of experience. Part is an economically-driven disrespect for time. (Give childbirth some motherlovin' time.) Another part, related very much to experience, is how difficult it is to decide when intervention is and isn't necessary, especially when things are heating up. But another part of the trouble actually lies in the evolutionary perspective. Unfortunately it's not all rainbows and unicorns when M.D.s embrace evolution. Instead, evolutionary thinking is biasing some medical professionals into believing that, for example, birth by surgical caesarean is an "evolutionary imperative."

Here's one recent example in The American Journal of Obstetrics & Gynecology of how the evolutionary perspective is (mis)guiding arguments for increased medical intervention in childbirth.

link to paper

It's a fairly straight-forward study of over 22,000 birth records at a hospital in Jerusalem. The authors ask whether birth weight (BW) or head circumference (HC) is more of a driver of childbirth interventions (instrumental delivery and unplanned caesareans) than the other. Of course, the focus is on the biggest babies with the biggest heads causing all the trouble, so the authors narrow the data down to the 95th percentile for both. Presumably they're asking this question about BW and HC because both can be estimated with prenatal screening. So there's the hope of improving delivery outcomes here. And, of course, the reason they ask whether head size or body mass is more of a problem is because of evolution. They anticipate that they'll discover that heads are a bigger problem than bodies because of the well-known "obstetrical dilemma" (OD) hypothesis in anthropology.

OD thinking goes like this: Big heads and small birth canals are adaptive for our species' cognition and locomotion, respectively, but the two traits cause a problem at birth, which is not only difficult but results in our species' peculiar brand of useless babies. (But see and see.)

So, since we're on the OD train, it's no surprise when we read how the authors demonstrate and, thus, conclude that indeed HC (head circumference) is more strongly associated with childbirth interventions than BW (birth weight), at least when we're up in the 95th percentile of BW and HC. Okay.

They use this finding to advocate for prenatal estimation of head size to prepare for any difficulties a mother and her fetus may be facing soon. Okay.

Sounds good. Sounds really good if you support healthy moms and babies. But it also sounds really good if you already see these risks to childbirth through the lens of the "obstetrical dilemma" with that OD thinking helping you to support "the evolutionary imperative" of the c-section. Okay.

Too many "Okays" you're thinking? You're right. There's a catch.

When you dig into the paper you see that "large HC" heads are usually about an inch (~ 2.5 cm) greater in circumference than "normal HC" ones. (Nevermind that we chopped up a continuum of quantitative variation to put heads in arbitrary categories for statistical analysis.) And when you calculate the head diameter based on the head circumference, there is less than 1 cm difference between "large" and "normal" neonatal heads in diameter. That doesn't seem like a whole lot considering how women's bony pelvic dimensions can vary more than that.  Still, these data suggest that the difference between a  relatively low risk of having a c-section and a relatively high risk of having a c-section amounts to less than a centimeter in fetal head diameter. And maybe it does. Nobody's saying that big heads aren't a major problem sometimes! But maybe there's something else to consider that the paper absolutely didn't.

Neonatal heads get squeezed and molded into interesting shapes in the birth canal.

The data say that normal HC babies get born vaginally more often than large HC ones. But this is based on the head measures of babies who are already born! If we're pitting head circumference (HC) of babies plucked from the uterus against the HC of babies who've been through hello! then of course the vaginally delivered ones could have smaller HCs.

C-sected babies tend to have rounder heads than the ones squeezed by the birth canal. It's impossible to know but I'm fairly confident about this, at least for a subsample of a population: Birth the same baby from the same mother both ways, vaginally and surgically, and its head after c-section will have a larger HC than its squeezed conehead will after natural birth.

Measuring newborn head circumference (HC). source

When we're talking about roughly 2.5 cm difference in circumference or less than 1 cm difference in diameter, then I'd say it's possible that neonatal cranial plasticity is mucking up these data; we're sending c-sected babies over into the "large HC" part of the story just because they were c-sected in the first place. So without accounting for this phenomenon, the claim that large head circumference is more of a cause of birth intervention, of unplanned c-sections, than large body mass isn't as believable.

If these thoughts about neonatal cranial molding are worthwhile, then here we have a seemingly useful and very high-profile professional study, grounded in the popular but deeply flawed obstetrical dilemma hypothesis, that is arguing for medical intervention in childbirth based solely on the difference in head size measures induced by those very medical interventions. 

The circle of life!

'Obstetric dilemma' skeptic has c-section and remains skeptical ... & ... Why my c-section was natural childbirth

This is a new kind of Tale for me. The rock'n'roll's turned way up, and every couple sentences I have to stop typing to twirl a blue hound dog, a bear holding an umbrella, a Flying Spaghetti Monster, and other oddities that I strung up to hypnotize this little guy into letting me type one thought at a time:

The thing that needs to be hypnotized.
Or the three wise monkeys say: The thing that makes it impossible to create or to dwell on the negative. (e.g. his birth by c-section)

That young primate's the reason I've been quiet for a while here on the MT. And he's the reason I'm a bit more emotional and I cry harder than usual at Rise of the Planet of the Apes (those poor apes!), Cujo (that poor dog!), and other tearjerkers. But he's also the reason my new favorite animal is plain old, fascinating, and dropdead adorable Homo sapiens.

In anthropological terms, he's the reason I'm overwhelmed, not just in love but in new thinking and new questions about the evolution of human life history and reproduction, and then what culture's got to do with it and with our reconstruction of it.

Some context would help, probably.

For the past few years I've been challenging the 'obstetric dilemma' hypothesis--the idea that hominin mothers' bipedal pelves have shortened our species' gestation length and caused infant helplessness, and that antagonistic selection between big-brained babies and constrained bipedal mothers' pelves explains childbirth difficulty too.

[For background see here or here or here or here.]

As part of all that, I've been arguing that the historically recent surge of c-sections and our misguided assumptions about childbirth difficulty and mortality have muddled our thinking about human evolution.

So, once I was pregnant, you might imagine how anxious I was to experience labor and childbirth for myself, to feel what the onset of labor was like, and to feel that notorious "crunch" that is our species's particular brand of childbirth. Luckily I was not anxious about much else the future might hold because modern medicine, paid for by my ample health insurance, would always be there to make it all okay. After a long pregnancy that I didn't enjoy (and am astonished by people who do) I was very much looking forward to experiencing childbirth. In the end, however, my labor was induced and I had a bleeping c-section.

But my bleeping c-section's only worth cussing over for academic reasons because the outcome has been marvelous, and the experience itself was out of this world.

We'll get to the reasons for my c-section in a second, but before that, here are the not-reasons...

First of all, I did not have a c-section because I fell out of a tree with a full bladder.

Second of all, shut your mouth... a c-section was not inevitable because of my hips.

Okay, you got me. I've never been even remotely described as built for babymaking. My hips are only eye-catching in their asymmetry. One side flares out. It might be because when I was 15 years old I walked bent-kneed for a few months pre- and post-ACL reconstruction. That leg's iliac crest may have formed differently under those abnormal forces because, at 15, it probably wasn't fused and done growing yet. If you like thinking in paleoanthropological terms like I do, then my left side is so Lucy.

Anyway. I'm not wide-hipped. However, guess how many nurses, doctors, or midwives who were involved in our baby's birth think my pelvis was a note-worthy factor in my c-section? Not one.

Hips do lie! Inside mine there's plenty of room to birth a large baby. Two independent pelvic exams from different midwives (who knew nothing of my research interests at the time) told me so, and it sounded like routine news to boot. Although one midwife asked me "do you wear size nine and a half shoes?" (no, I wear 8) which was her way of saying, "Girl, you're running a big-and-tall business. You got this."

What you probably know from being alive and knowing other people who were also born and who are alive (or what you might hear if you ask a health professional in the childbirth biz) is that most women are able to birth babies vaginally, even larger-than-average babies. And that goes for most women who have ever lived. Today, "most women" includes many who have c-sections because not all c-sections are performed because of tight fit between mother's birth canal and baby's size. As I understand it, once the kid's started down into the birth canal and gets stuck, a c-section's no longer in the cards. So performing c-sections for tight fit is a preventative measure based on a probability, not a reflection of an actual tight fit. In the mid 20th century, tight fit used to be estimated by x-raying pregnant women and their fetuses. Can you imagine? And this was right about the time the obstetric dilemma hypothesis was born. I don't think that's a coincidence.

Here's a list of reasons for c-sections. Tight fit is included in the first bullet point. Tight fit is one of the few quantifiable childbirth risks. No wonder it's so prominent in our minds. That list excludes "elective" ones which can be done, at least in Rhode Island, if they check the box that says "fear of childbirth". And that's not even close to a list of reasons why women around the world and throughout history have died during or as a result of childbirth. For example, about a hundred years ago women were dying all over the place because of childbed fever.

Anyway, we should assume that I am like most women and expect that I could have given birth the way Mother Nature intended: through my birth canal and with the participation of other humans. Oh yeah, when it comes to humans, social behavior and received knowledge are part of natural childbirth. Even this natural childbirth (which has inspired a forthcoming reality television show featuring women giving birth in the wild!) involves the supportive and beneficial presence of other humans as well as the culture that the mother brings to the experience.

But a c-section's just culture too, so could it be part of "natural" childbirth, then?

I'm inclined to blurt out yes, of course! because I don't support calling anything that humans do "unnatural." But I know that's not something everyone agrees with. It's politics. For example, many of you out there don't flinch an inch at the subtitle of Elizabeth Kolbert's book, "The Sixth Extinction: An Unnatural History."  And given the present energetic movement against childbirth interventions, describing c-sections as "unnatural" as climate change could help minimize unnecessary ones for those who wish to give birth vaginally.

So there we have it. These are the two enormous issues raised by my own little c-section: What can it teach us about the evolution of gestation length, infant helplessness, and childbirth difficulty? And could it be considered natural?

One way for me to get at these questions is to try to understand why I experienced "unnatural" childbirth in the first place. So here goes.

Here's why I think I had to have a c-section:

1. My pregnancy ran into overtime.

This is expected for nulliparous mothers. I visited one of my OBs on my due date. He put his finger on the calendar on the Friday that was two weeks out and joked, "Here's when we all go to jail." Then he asked me, "Who do you want to deliver your baby? I'll see when they're on call before that Friday and schedule your induction then." And I chose my favorite midwife and he scheduled the induction.

All right so I was running late compared to most women, but that's still natural, normal. But it also means risks are ever-increasing by the day. And no matter how small, that the professionals know how to mitigate the biggest risks of all, *deaths*, means that they try to do that. They're on alert already as it is, and then they're even moreso on edge when you're overdue. Especially when it's your first baby and you're a geezer, over 35 years of age.

Now, does going overdue mean the baby keeps growing? Maybe, but not necessarily and not necessarily substantially. Both of us, together, should have been reaching our maximum, metabolically. There's only so much growing a fetus can do inside a mother.

When I approached my due date, and then once I went past it, I tried to eat fewer sweets to make it less comfortable in my womb. I also went back to taking long, hard walks, five milers, even though it was hard on my bladder because I thought that might help kick him out too. I even ran the last of my five miles the day before my induction, to no avail other than the mood boost it gave me.

2. I didn't go into labor naturally by my due date or by my induction date 11 days later. 

Although my cervix was ripening, when I went in to be induced I was only dilated 0-1 cm. I had 9+ more to go before the kid could get out at 10. So a balloon catheter was inserted and filled with water, and I had to tug on the tail of it, which tugged the balloon, which put pressure on the cervix. It dilated enough that it fell out several hours into the process, and by morning I was dilated 3-4 cm. This was exactly the goal of the catheter, this many centimeters. All was going well. However, that the cervix did not open on its own is already a missing piece of going "natural," of having my own biology contribute to my childbirth experience. So starting this way is already derailing things, making it difficult for anything natural to follow, naturally.

3. The fetus's head was facing the hard way: sunnyside up.

This was assessed by the midwife and cradling my belly in a bedsheet, with me on all fours, she and I could not twist him into a better position. His head, she said, was probably why I did not dilate naturally. When I asked an OB during my postpartum check-up, "What dilates the cervix?", he said "We don't know. But I can tell you it's not with the head like it's a battering ram." Well, then... hmph. And then I asked him if women carrying breech fetuses have trouble dilating their cervixes, or going into labor naturally, and he said not necessarily. No. Hmph.

Regardless of what causes cervical dilation, if the head isn't facing the right direction, it's notoriously tough to get down into the birth canal, let alone through the birth canal. It's not impossible, not even close. But it's not looking good at this point either. Perhaps the contractions will jossle his head into a better position, they said. And the contractions should further dilate the cervix.

4. Contractions didn't get underway, naturally, after the catheter dilation, so the drug pitocin was used. 

Induction and pitocin increase the chances that a mother will ask for drugs to help with pain and that she will have interventions, like a c-section. See for example this paper. What the causes are, I'm not sure. But pointing out the correlation is useful at this point because at this point, without even getting into hard labor yet, and without finding out whether my cervix does its job, I'm more likely than ever to be going to the operating room.

5. After six hours of easy labor and five hours of intense labor, my cervix never dilated past 5 cm.  

It needs to get to 10 cm to get the baby moving into the birth canal. Just like with due dates, I think that blanketly assigning this number to all women is probably not consistent with variable biology, but it's how it's currently done. And maybe any higher resolution, like "Sally's cervix needs to hit 9.7 cm", is pointless.

After several hours pitocin-induced contractions--which at first felt like the no-big-deal Braxton-Hicks ones I'd been having numerous times daily for the whole third trimester--I only dilated 1 cm more. That's even when they upped the pitocin to make them more intense.

But after they saw I'd made essentially no progress and that I was napping to save my energy for when things got bad, they woke me up and broke my bag. It would be nice if they could have let my labor progress slowly, if that's what my body wanted to do, but remember, my personal biology went out the window as soon as induction began. And then when that amniotic fluid oozed out of me, that's when bleep got real.

Every two minutes and then every one and a half, I grabbed Kevin's extended hand and breathed like an angry buffalo humping a locomotive. It was the worst pain of my life and I was afraid I'd never last to 10 cm, so I took the stadol when I told the nurse my pain was now at a 9 out of 10 (all previous answers to this question were no higher than 2). I was going to avoid the epidural no matter what, even at this point, because I was more afraid of the needle sticking out of my spine for hours of labor than I was afraid of these contractions. I have no idea if the stadol dulled any pain, because the pain just got worse, but it did help psychologically because it put me to sleep between contractions. There was no waiting with anxiety for the next one and time flew by. But after five hours of this, I had not dilated any more. But I had vomited plenty! And although I'd fended off the acupuncture (FFS!), I folded weakly and, for the peace of mind of a wonderfully caring nurse, I allowed a volunteer to perform reiki on me. And what a tragedy it was! Wherever she is, there's a good chance she gave up trying to help laboring women, and she may have given up reiki all-together.

The hard labor story ends at five hours because that's about when the nurse actually screamed into the intercom for the doctor. My contractions were sending the fetus into distress.

6. After five hours of intense labor, the fetus was experiencing "distress" at every contraction, as interpreted from his heart-rate monitor. 

Basically, he was bottoming out to a scary heart-rate and only very slowly coming back to a healthy heart-rate just in time to get nailed by another contraction. By the way, this is the official reason listed in my medical records for my c-section: fetal distress.

I know that a heart-rate monitor on the fetus is another one of those medical practices that increases the chances of an "unnatural" childbirth. That's probably because all fetuses are distressed during labor, but observing the horror, and then guessing whether it's safe to let it continue is seemingly impossible. So at some point, like with me and my fetus, they get alarmed and then how do you back down from that?  They gave me an oxygen mask which immediately helped the fetus a bit, but like I said, hackles were already up at this point. Soon thereafter we had a talk with the doctor about how I  could go several more hours like this and get absolutely nowhere with my cervix, and then there are those life and death matters. She never said c-section. I had to eek out between contractions, "So are you saying we need to perform a c-section?" and she said yes, and urgently. A c-section sounded like the only solution at this point both to battered, old me, to clear-minded Kevin, and clearly to the delivery team (and in hindsight, it still does to Kevin and me). Then, lickety-split, the anaesthesiologist arrived, got acquainted with our situation, and made me vomit more. And then like a whirlwind, Kevin's putting on scrubs, and we're told to kiss, and I'm jokingly protesting "I'm a doctor too!" while being wheeled into the operating room because I cannot walk through my contractions.

It's bright white, just like Monty Python said it would be. I sat on the crucifix-shaped operating table to receive all the numbing and pain killing agents through my spine. Somehow they pulled this off while I was still having massive contractions. Then I laid down, arms splayed out to the side, and they drew a curtain across my chest, a nurse told me how creepy it was about to be, and they got to work.

Although the c-section wasn't painful, I could feel everything. This was my childbirth experience. I felt the incision as if she was simply running her finger across my belly, and I felt the tugging and the pressure lifting from my back as they extracted my baby from me. After that, and after I got a short glimpse of him dangly over my left arm--"He's beautiful! He's perfect! He's got a dimple! He growled!"--I continued to feel many things, probably the birth of my placenta, etc...

But I didn't know what exactly I was feeling until I watched a video of a c-section on YouTube. Kevin helped fill in the details too. He had caught a naughty glimpse of the afterbirth scene before being chased back to his designated OR spot with the baby. Thanks to him (and that video) I know now that I was feeling my enormous muscular uterus and some of my intestines being yanked completely out of a small hole right above my pubic bones and then stuffed back in. For a few moments, it must have looked like I was getting re-inseminated by a red octopus.

I tell everyone that it was like going to outer space to give birth. And this, if you know me, is an exciting idea so my eyes are smiling and I sound dreamy when I say "it was like going to outer space to give birth!" I bet you're thinking it's the Prometheus influence, but you'd have the wrong movie. The correct one is Enemy Mine. And it's much more than that, actually. I was as jaw-dropped and awe-struck by humanity during my childbirth experience as I am by space exploration. The orchestration, the specialization, the patience, the years of study, of planning, the calculations, the dexterity. To boldly go. Wow. Like I said, humans are my new favorite animal.

I was back in our little room quicker than most pizza deliveries, where our bright red new baby was trying hard to nurse from his daddy. Then he nursed from me. And the story's all mushy weepy cuddly stuff from now on. So let's not. Let's remember what we're here for. Okay. Right.

7. The cord was wrapped twice around his neck. 

We found this out when he was cut out of me. That didn't help with moving him around in utero to a good position, nor did it help with oxygen flow during contractions! This would not have inhibited his safe vaginal birth, however, at least not necessarily.

8. He was enormous. His head was enormous too. 

He came out a whopping 9 pounds, 13 ounces, 22.25 inches long, with a head circumference of 15.5 inches. They say that's heavier than he'd be if born vaginally because he didn't get all the fluids squeezed out of him. But still, that's large. According to the CDC he was born as heavy as an average 3.5 month-old boy. His head was about the size of an average 2.5 month-old.

Red line is our baby's head circumference at birth. (source)

Way back at the mid-pregnancy ultra-sound, we knew he was going to be something. And then if you'd seen me by the end, like on my due date, you might have guessed I was carrying twins. I was so big that my mom joked she thought maybe a second fetus was hiding behind the other one, undetected.

Smiling on my due date because pregnancy was almost over. 
(By the way, I could still jog and I dressed weird while my body was weird.)

If I hadn't had the means to eat so much like I did during pregnancy, perhaps he wouldn't have grown so large inside me. If I hadn't lived such a relaxed lifestyle while pregnant, maybe he wouldn't have grown so large inside me. If I didn't have a medical safety net waiting for us at the end, perhaps I would have been scared into curbing my appetite from the get go. I gained 40 pounds. With this body, but in a different life, a different place, a different time, maybe I wouldn't have. Probably I wouldn't have.

His size has got to have influenced a few of those other contributors to my c-section. But clearly it's more complicated than his size. And this brings us back to the obstetric dilemma. Let's say he was too big or that his large size screwed everything up, even if he could technically fit through the birth canal. Well then, why didn't I go into labor? Labor triggers are, to me, a significant problem when it comes to explaining the evolution of gestation length in humans, and whether we have a unique problem at the end.

If our pregnancy length is determined by available energy, energy use, and metabolism (here and here) then women like me who go overdue, who are clearly not killing our babies inside us either, are just ... able to do that. But doing that clearly leads to problems in our species (one of the few known) that has such a tight fit to begin with.

If our pregnancy length is determined by our birth canal size, and any anatomical correlates, then why didn't I go into labor before my fetus got so big? What went wrong? What's frustrating too is, for my n of 1, we'll never know if I could have given birth vaginally because I never got the chance to try.

These seem like simple questions but they are deceptively complex. And I think there will be some exciting discoveries to come from medicine and anthropology in the coming decades to explain just how our reproduction works which will in turn help us reconstruct how it evolved.

What's my birth experience got to do with evolution? Why, everything. It's got everything to do with evolution, because if it's not evolution, it's magic.  And that's kind of where I'm coming from when I say that my c-section was still natural childbirth. It wasn't unnatural and it certainly wasn't supernatural. Sure, it's politics. I'm invested in the perspective that humans are part of the evolving, natural world and want others to see it that way or, simply, to understand how so many of us see it that way. But it's not just evolution that's got me enveloping culture into nature and that's got me all soft on the folks who drive fancy cars who cut my baby out of me.

Who knows what could have happened to my son or to me if we didn't have these people who know how to minimize the chances of our death? It's absolutely human to accumulate knowledge, like my nurses, midwives and doctors have about childbirth. Once learned, it's difficult for that knowledge to be unseen, unheard, unspoken, unknown. Why should we expect them to throw all that away so that we can experience some form of human being prior to that knowledge?

Nature vs. Culture? That's the wrong battle.
What matters is which one can fight hardest on my behalf against the unthinkable.

Maybe childbirth is so difficult because it can be. We've got all this culture to help out when things get dicey, with or without surgeons. On that note, maybe babies are so helpless because they can be. We've got all the anatomy and cognition to care for them and although the experiment would be impossible, it's doubtful any other species but ours could keep a human baby alive for very long. It could just be our dexterous hands and arms, but it could be so much more, like awareness of their vulnerability and their mortality,and (my favorite pet idea) awareness that they're related to us. Culture births and keeps human children alive with or without obstetricians. It's in our nature. Maybe it's time we let all this culture, our fundamental nature, extend into the operating room.

Fairy stories and evolutionary medicine

Plausible does not mean probable
Nothing in medicine makes sense except in the light of evolution!  So goes a modification of the great 20th century evolutionary biologist Theodosius Dobzhansky's statement about biology; Dobzhansky was advocating the teaching of evolution in the schools, but his quip is now tailored as the dictum of the field of evolutionary medicine (EM).

EM is the idea that evolutionary theory can be used to explain why we get the diseases we do.  That is, when something goes wrong with the body, it's because our genome evolved long ago, in a very different ecological context, and thus we're not adapted to life in the modern world.  We're out of sync with our evolutionary history, and this is what leads to disease.  And should, as a consequence, inform clinical practice.

A very nicely argued paper by Michael Cournoyea in the latest Perspectives in Biology and Medicine ("Ancestral Assumptions and the Clinical Uncertainty of Evolutionary Medicine") questions the theoretical basis of this idea, as well as its clinical relevance.  He refers to two recent collections of writings on EM, noting that they include chapters on

...nutrition, type 2 diabetes, childbirth, menstruation, stress, altitude sickness, sleep, heart disease, obesity, addiction, delusions, and more. For example, contributors suggest that addiction is just the malfunctioning of ancestral wanting and seeking mechanisms in modern lifestyles; sleep problems reflect an ancestral tension between the need to remain vigilant and the need to rest; and the life of those with chronic heart failure may be prolonged by blocking ancient neurohormonal adaptations.

These kinds of arguments are not uncommon even in everyday analyses of modern society: it's often said, e.g., that severe anxiety disorder is common in today's stressful society, when we have to do things we did not evolve to do like public speaking or driving across bridges.  But anxiety evolved as a normal defensive response to fearful situations, and at the time was adaptive rather than debilitating.  Too little anxiety would have been selected against, because, well, it's obvious -- he who had no fear of lions was dinner. 

Cournoyea describes the classic example of the practical uses of EM.  Fever, it is thought, must have evolved for a reason.  Because it accompanies illness, it must somehow help the immune system combat infection.  Therefore, it's probably best to leave fever untreated.  But, as he says, while this idea might pinpoint a way for researchers to study fever, it isn't clear that this is relevant to clinical practice, and the conclusion warranted. 

Cournoyea stresses the difference between evolutionary explanations on the micro scale (antibiotic resistance, or the evolution of influenza viruses, e.g.) and the macro scale ("the origin and adaptive function of physiological processes" such as breast-feeding), noting that the application of evolutionary theory to the first is much more informative than the speculative kinds of applications that are considered in the longer time scale, and indeed the only kinds of applications that can be considered since these traits evolved so long ago.  Why did fever or menopause evolve?  These questions can't be answered other than speculatively.  Yet, much of evolutionary medicine is dedicated to answering such questions.  And, as Cournoyea points out, generally from a strong adaptationist perspective.

I conclude that faults in these fundamental assumptions undermine EM’s central objective of providing clinically relevant medical knowledge. I maintain that evolution’s place in the clinic is controversial at best, and that these conceptual blind spots lead to misguided conclusions about our supposed human nature.

As he also points out, many evolutionary theorists by now have questioned the assumption that all traits have been molded by natural selection to be highly adaptive, but EM is built on this assumption.  "Developmental constraints and the nonselective mechanisms of evolution are given a backseat to adaptive functionality..."  But, he writes, explanations of ultimate causation, the adaptive hypotheses put forward by EM, are not relevant to clinical practice. And we think it is defensible to assert that many who make evolutionary arguments of this sort have only a cartoon understanding of how evolution works.

And there's more
As regular readers of MT know, we harp on the problem of assuming adaptation and the all-encompassing role of natural selection in evolution, all the time, so we are in complete agreement with Cournoyea's critique of EM in this regard.  But there's another fundamental problem with EM that Cournoyea's spot-on paper doesn't address -- not that it should -- and that is the idea that we evolved in a given environment to be highly adapted to that environment, and that one alone.

Organisms that are highly adapted to a single environment, unable to adapt to change, are very vulnerable.  Or, put another way, extinct.  One of the most ubiquitous characteristics of life, so ubiquitous that we've called it a principle of life, is facultativeness, the ability to adapt to change.  The "paleo diet" craze is another 'philosophy' founded on the idea that we evolved to eat the raw foods that our ancestors ate as they were becoming modern, and thus that we only achieve optimal health following that diet.

But by this logic, we're in danger of going down Alfred Russel Wallace's slippery path to excepting humans from evolution.  And he was by no means alone in invoking human exceptionalism in such contexts (Darwin did it in his own way, too).  Indeed, we might even find ourselves attending seances as Wallace did late in life.  He thought that the human ability to do calculus was evidence that it was impossible for us to have evolved by natural selection alone, because the human brain didn't evolve doing calculus.  Similarly, because we didn't evolve eating Twinkies, they must be lethal.

But we can do calculus, because what evolved was our brain's ability to figure things out.  We didn't evolve knowing how to cross busy city streets either, but we can do that, too, and we can build rockets and go to the moon.  And, people eat a huge range of foods now, and have done as we evolved -- there are 7 billion of us on Earth, speaking thousands of languages and still eating varied diets, so clearly we're adaptable.  There's no one way to be human -- nor are there single pathways to disease.

Fairy stories can't always be refuted, but that doesn't make them true
Just because we can invoke -- or, basically, assume -- a principle of nature, like natural selection, this doesn't mean that the principle works without exception or is invoked in an empirically correct way.   But if a tale is being told that rests on that assumption, there is a very widespread tendency to let the assumption slip by without justification, and accept the fable and its moral.  Fairy stories can't be refuted if the existence of fairies is assumed, not something to prove before we judge the story itself.

Likewise, despite Darwin's venerable insights, natural selection is a possible aspect of evolution -- nobody can doubt that -- but it is an aspect, not a law of nature.  Other factors, notably chance and implications of organizational complexity, greatly modify what one can legitimately say about selection.  This is so widely understood by those who care to look at things carefully that there is no excuse for the widespread uncritical selectionism so widely assumed about Nature by so many, in evolutionary medicine but also in evolutionary psychology, too much of anthropology, genetics, and beyond.

If you assume that some trait is the result of natural selection, then you can make up stories as to how it worked to produce your particular trait.  If your first guess doesn't fit, then you feel justified to make up counter-adaptationist stories.  But if selection is assumed, it can't be refuted since it's not open to test.
Just because a tale is possible, or seems plausible, this does not in any way make it true, especially if its basic premise is not open to question, as is so often the case in biomedical research or EM.

And Dobzhansky's quip?
The co-opting of Dobzhanksy's quip is very telling.  As we also noted in our book MT, even in its original form with respect to biology, it is manifestly untrue. Did nothing in biological research make sense before Darwin?  While nothing in biology (or medicine, for that matter) is inconsistent with our understanding of evolution, it is just not true that nothing 'makes sense' except in that context.

The blatantly obvious truth of this is that much of biomedical research has nothing to do with evolution, as well as the fact that many if not most people in the field know very little about evolution beyond a caricature (and, of course, many creationists of various religions work in biology and medicine).  But the slogan can be routinely invoked without any critical assessment by almost anybody, even in biology, including a cult -- and that's the right way to characterize it -- of a few leaders of EM whose words seem rarely to be questioned, much less critiqued properly.  This fact shows that invoking the quote isn't that different from saying a rosary: a comfortable, feel-good reinforcement of what often amounts to little more than a mantra of an ideology.  That's not the same as science!

It's a shame people have to be this way, because the scientific challenges are serious, and there is much that we don't know about evolution; the subject deserves better for its own sake, and for the public that pays for results.