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What Is Wrong with Dissections?

The views expressed are those of the author and are not necessarily those of Scientific American.


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Hint… It is not what you think.

Here is a story you might find a bit laughable. At the end of the dark ages in what is now Italy, when knowledge was being reborn, anatomists would read from an ancient Greek text while their assistants dissected a human body and pointed out its parts. If the body looked different from what was written in the thousand year old text it was seen to be mutant, deviant, wrong. No matter that the ancient Greek knowledge was flawed and many of the rather ordinary observations that were being made would have improved dramatically upon what was known. Man, those early anatomists were dopes. It would take a major scientific revolution for anatomists to begin to actually observe and learn from dissections. The idea that more knowledge could be gained was a breakthrough. Isn’t it crazy how hard it was for early scientists to figure out obvious things? Boy oh boy.

Image 1. An early anatomy theater at the University of Leiden.

I was thinking about this the other day when I walked past a classroom in which undergraduates were dissecting cats.  Around the world, millions of cats, dogs, pigs and other mammals, including thousands and thousands of humans are dissected in anatomy classes. They are dissected in order to teach students—including all of those who will eventually operate on your body—about how an average mammal, amphibian or other body works.

One can discuss the merits of having students perform dissections.  One can also discuss the morality of such dissections. I won’t do either. I want to get at something else, the issue of whether these students are doing exactly the same sort of science that was being done at the end of the dark ages.

In an average anatomy class dead animals are handed out to students. A tired/sometimes grumpy/overworked/underpaid teaching assistant discusses how the dissection should be done. Students perform various forms of butchery. Students label/point to/remove parts of the body on which the teaching assistant has told them to focus. In focusing on these parts of the body, the students are told about how it works, or at least how it works in general. More body parts are dissected. More knowledge is provided. The bodies are then thrown away in special trashcans. The teaching assistant goes home to work on their thesis and to wonder if he/she will ever get the job. The students go home to think about other students/beer/ or other students. The whole process repeats with a new group the next morning.

I don’t mean to make fun of the hard work of students or teaching assistants. What I do mean to make fun of is that we seem to now teach anatomy in exactly the same way that it was being taught at the end of the dark ages. Specifically, students look at bodies of animals, but are not encouraged in any way to make real observations. Instead, they are encouraged to look for what is already known and then if it does not look quite right, do depict it the way it “should,” look. Even where the differences among bodies are noted, they are seldom measured. Even when measurements are taken, they are seldom recorded.

Now, you might say, Rob, you are confusing things. At the end of the dark ages we were ignorant about the body. Simple measurements could produce new knowledge. Now we understand the body. Of course, there is that difference. You are right, or you would be except that we still don’t understand the bodies of animals all that well. The function of the appendix is under new scrutiny. The stomach too. In fact, when it comes to basic morphology, the sorts of things that can be measured by preoccupied students in large classes, we haven’t made that much progress in the last hundred years (This is where you, as the reader, cue in on your favorite exception to my sweeping generalization and then go on to mention it in the comments section). How and why do intestines vary among individuals? How frequent are different deformations of particular organs. Are there tradeoffs between investment in one organ and in another? How frequent are rare mutations in the bodies of cats, pigs or even humans, mutations that we still don’t understand very well at all. Such mutations are hard to study because of their very rarity, but we dissect so many pigs, cats and other animals that even something that turns up in just one in a million animals turns up somewhere in some class each year. What else could be studied? I’m sure you can think of obvious features I am missing. The point is there are discoveries right beneath students as they look up at their teaching assistants or teachers, but we are training them to ignore them, to see the general story at the expense of the truth.

What now? I have one idea, probably an overly simple one, inspired by work in citizen science.  I would have students take real measurements along with high-resolution digital images of the animals, including humans, that they dissect. They would also take a sample of some tissue of each animal (This might need to occur before the animals were preserved which would be harder, but still possible). The images and measurements would be sent to a database where they could be compared with others of the same. The tissue would be shipped to a tissue bank. With the database, anyone could compare the features of animals to understand how much they vary. With the tissue bank, the genes associated with unusual features could be narrowed down upon. With every moment in class, the students, however sleepy, however focused on the girl or boy in front of them, would be reminded that the body they are looking at is, like their own body, still imperfectly, understood. That was the revelation that would come after the dark ages, in the late renascence. It is a revelation we would do well to build upon as we consider how our own science and education might, together, be reborn, or, if not reborn, just done in such a way as to allow students to pay a little more attention to the dead pig in the hand, which, as they say, is worth ten in the book. Maybe they don’t really say that, but you get the idea.

Image 2. Evidence of Michelangelo’s hard work paying attention during the dissections he performed.

I was going to end there but then I remembered the one place, the only place in which students are actually taught to pay attention to the bodies they see before them, art classes. In figure drawings classes a naked man or woman stands in front of a room of students and is observed, drawn, piece by piece. We could learn something from these art students and their teachers. Ironically, the same was also true at the end of the dark ages, when, long before the scientists began to pay attention to bodies, the artists did. The artists had to, they were charged by their instructors with portraying truths in contrast to the science students who were (and are) charged only with portraying what is already known.

Note: I use the term “dark ages” here. As one commenter notes, Early Middle Ages is the term historians now tend to use. However, from the point of view of biology in general and anatomy in particular, the times were dark. For many fields of biology more was known in 100 BC than was known in 1400 AD. Whatever you call the intervening years, scientifically they were illuminated by precious little light.

Rob Dunn About the Author: Rob Dunn is a science writer and biologist in the Department of Biology at North Carolina State University. His first book, Every Living Thing, told the stories of the sometimes obsessive, occasionally mad, and always determined, biologists who have sought to discover the limits of the living world. His new book, The Wild Life of Our Bodies, explores how changes in our interactions with other species, be they the bacteria on our skin, forehead mites or tigers, have affected our health and well being. Rob lives in Raleigh, North Carolina with his wife, two children, and lots of microbes. Follow on Twitter @RobRDunn.

The views expressed are those of the author and are not necessarily those of Scientific American.






Comments 13 Comments

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  1. 1. Thony C. 12:16 pm 05/12/2013

    A nice post and an interesting view on the ‘blindness’ of medical anatomists during the High Middle Ages. However I do have one, for historians not small, quibble. The term dark ages is obsolete and should not be used. The period you wished to refer to is now termed the Early Middle Ages.

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  2. 2. leaf6 1:06 pm 05/12/2013

    Thus we have the advent of personalized medicine. The field can really benefit from Rob Dunn’s suggestions.

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  3. 3. Bora Zivkovic 1:59 pm 05/12/2013

    @Thony C. – this always puts me in a quandary. On one hand, I know historians will chastise me for using an inaccurate, outdated term. On the other hand, the term “dark ages” is a metaphor, a writer’s shorthand for a time (of often unspecified exact timing and duration) in the past when knowledge was different and the methods of acquiring knowledge were different than today.

    @Rob Dunn – I am one of those (hopefully not as grumpy) people who TAd dissection labs for many years. I could not do then what you suggest now, if nothing else because the Web was not as developed back then, but I did my best. I forced my students to always go around the lab and look at all, usually 24, cats (or dogsharks or mudpuppies or fetal pigs) and to note the subtle individual differences, e.g., the numbers and locations of arteries branching off of the aorta, etc.

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  4. 4. lcwelch 2:26 pm 05/12/2013

    As a one time student of an undergraduate human anatomy course, I don’t see how time permits what is proposed. I had a hard enough time learning the basics in a quarter. Analyzing structures I had just been taught would have been too much. I would hope that those that go on to do graduate work in anatomy do this. In general, I don’t think undergraduates are expected or able to make great scientific discovery. They are there to learn a broad range of basic scientific categories. After that basic scientific education and training, undergrads can choose to pursue a specialized graduate degree. They can the focus time, energy, and money on graduate work that emphasizes discovery.

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  5. 5. Sarah Zielinski 2:37 pm 05/12/2013

    I got frustrated with the balance of death vs. benefit (i.e.,learning) during a marine invertebrates class in college. We seemed to be killing a lot of critters every week for not that much knowledge. I’m not anti-dissection, but I’m uncomfortable with the scale of death that occurs often with little learning. I like the idea of increasing the benefit side of the equation, though. It makes all that death a lot more palatable.

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  6. 6. HertfordshireChris 4:30 pm 05/12/2013

    The article starts “Here is a story you might find a bit laughable.  … Isn’t it crazy how hard it was for early scientists to figure out obvious things? Boy oh boy. “

    One of the limitations of the human mind is confirmation bias – where you believe what supports your earlier position and reject observations which do not conform. Before you laugh can you be certain that people will not be laughing at the way we fail to spot the errors in our own view of the world.

    Failure to anticipate and take adequate action about the effect of burning fossil fuels is likely not so laughable critique of 20th century science and 21st century politicians.

    In addition my own research suggest another area where the future may be laughing at us. This is the failure pf brain researchers to find the “neural programming code” which relates neuron activity to human intelligence. The general approach seems to be that the answer must be very complex because we can’t find it. No-one seems to be looking for a very simple answer because that could mean we aren’t really very intelligent and WE KNOW WE ARE INTELLIGENT. My work suggests that a really simple, crude, and logically weak model might be all we have at the biological level. Such a model predicts many human failings, including confirmation bias, and also suggests why, at the neuron level, we might be less intelligent than some animals. But don’t worry as the serious deficiencies in the brain’s mechanisms are partly hidden by layers of cultural intelligence.

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  7. 7. hanmeng 4:39 pm 05/12/2013

    A tired/grumpy/overworked/underpaid professor discusses how the assignment should be done. Students perform various forms research. Students label/point to/remove parts of the books/articles on which the professor has told them to focus. In focusing on these parts of the books/articles, the students are told about how knowledge works, or at least how it works in general. More body books/articles are read. More knowledge is provided. The books/articles are then thrown away in the special trashcan known as “memory”. The professor goes home to work on their research and to wonder if he/she will ever get the grant/promotion. The students go home to think about other students/beer/ or other students. The whole process repeats with a new group the next morning.

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  8. 8. jwpowless 7:24 pm 05/12/2013

    I have my high school biology students do three dissections: squid, shark, and rat. Learning the basics of anatomy and physiology is only a surface, measurable goal. My overall goal is deeper.

    After doing this for 20 years, I have found that the reason I keep running dissection labs is for fun. The students who enjoy being elbows deep in shark spiracle don’t know how much they like it until they find themselves doing it. The ones who are enthralled by measuring the entire length of the rat digestive system esophagus to rectum don’t know that about themselves either. Until they do it.

    I have never had a video or a computer simulation have that particular effect on a young person. This is where I get some of my future doctors and nurses. They find out during my humble dissection lab that they enjoy something other students do not. I don’t know why it works this way, but touching a (formerly) living thing so intimately stirs something in them. It awakens their desire to learn more, to do more. They somehow realize that if they can expose a shark or rat brain, that they someday could help out healing a living human one. For them, that’s fun.

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  9. 9. LeeB 1 7:44 pm 05/12/2013

    Art students are not the only people who have to draw things to learn.
    In a palaeontology course I was a student in we were expected to draw and label fossils so that we would learn to recognise them.
    It really helped both in recognising them and in making us really look at the fossils.

    LeeB.

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  10. 10. squidboy6 7:48 pm 05/12/2013

    I studied Invert Zoo at a UC in the middle 80s. Looking back it was the beginning of another dark age, but we did a lot of dissections of the major phyla. People were encouraged to get involved and two students per specimen was the case. This was a time when people began to speak out against dissection.

    I enjoyed the exercise if not the killing but if something was going to be sacrificed, and it was basically on its way to dying after collection, then it should be done well and as much as possible should be learned from it. As one noted above there was a time limit.

    Still I went on to collect specimens for research later and I learned a lot more about an organism from in situ specimens than dissection. It’s not for the faint-hearted, diving off coastal California, and modern techniques of digital photography and good computers were not yet available.

    I’m against vivisection but at the time we used freshly collected specimens so formaldehyde was not present (I would not have been able to stand being around cadavers soaked in that stuff) and some organisms like sipunculids were live. I think the tone for a class was set by the instructor and the two who taught that section were some of the best. They were looking for new grad students too.

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  11. 11. squidboy6 7:58 pm 05/12/2013

    I’d like to add that we were encouraged to sketch the specimen as well, and in stages, too.

    I really think a biology instructor who teaches Intelligent Design along with general biology is not going to be a teacher that produces good medical students or future biologists.

    jwpowless’ comment is important as well. There’s been such a revolution in molecular biology that students who never see a live tumor or heartbeat might never make the connection when they’re sequencing something or working with a germ cell.

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  12. 12. Diogenes11 8:54 pm 05/15/2013

    Thankfully I had great teachers like jwpowless to inspire me with the real, rather than the virtual world.
    Doing dissection as a med student taught me the opposite of the ancients, who tried to conform the reality to their philosophy. I learnt that structures are not colour-coded the way they are in the textbooks, and that in the real ex vivo specimen, the structures do not look like they do in a carefully photographed atlas, or even in modern 3-D software atlases. Even the haptic feedback was useful in developing surgical skills.

    Sorry Dr Dunn, but Michaelangelo’s hard work was principally in his comprehension of the human perceptual system. He cheated on his dissecting, so his David looks a lot better than the real one, who was described as the runt of his family. Read 1 Samuel 16 and 17, to see how he was handsome, but only a boy and physically unpreposessing at the time of this incident.
    Try this with mind’s eye/photoshop/old fashioned cut and paste:
    -Compare David’s thumb size to his (strangely for a Jewish boy, uncircumcised) penis and testicles.
    -Compare his head size with his knee
    -Place the heel of his hand on the chin, and his fingers wrap well over his hairline.
    -Compare hand and foot length.
    -Stare at him eye to eye (difficult, as he stands 5 metres tall on his plinth)

    David’s steely gaze is emphasized by grossly disconjugate eyes, in an overly large head, designed to be viewed by human eyes from 3 metres below. His hands and the sling (which loops over the shoulder and reinforces the marble of the left upper limb) are huge, to accentuate their prominence in his feat of single combat.
    And for one who is often considered the apex of masculinity, his genitals are underdeveloped, compared to his other secondary sexual characteristics of muscle development and pubic hair.
    Tough and handsome – no question. Anatomically accurate – good as Galen.

    Michaelangelo could have been a great scientific anatomist, but chose to be a great artist. Like the ancient anatomists, he does not ‘portray truths’, but deliberately conspires to alter truth to convey his message.

    I do like the idea of a tissue bank, but see no need to link it to dissections. Any blood sample could give DNA analysis and be linked to medical records (and eventually, autopsy/dissection).
    Who would fund it, and whom you would entrust to collate such data, is the real question – Medical students like Mr Tsarnaev? Obama? Putin? Kim Jong Un? The WHO?

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  13. 13. Toiski 12:50 pm 05/19/2013

    “In the past, x was wrong because of y. Therefore, x must necessarily be wrong now in the absence of y.”

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