We're not going to run out of new anatomy anytime soon
Comments
tgbugs
ASalazarMX
Interesting that such an important nerve could possibly have genetic instructions like "just grow around this direction and do branches".
elric
That was a super interesting read. Another factor that's probably missing is a weird form of prudeness/sexism. I remember reading articles years ago about new discoveries about the clitoris, and thinkig "how the fuck was this missed", or the debate around the existance of the G-spot, or the existence (or not) of female ejaculate. I suspect there's more female anatomy left to be discovered/described than male.
hiisukun
In addition to the appendix, my go to example of this is my friend's favourite organ: the Thymus [1]! If you've heard of "T-Cells" you indirectly know about it.
The interesting thing is that it is in a human when they are born, grows until puberty, then gets smaller and smaller until it can be quite small and difficult to detect in a grown adult.
I can imagine medical explorers cutting open dead 40 year olds in the year 1900, probably not finding any obvious organ there -- while perhaps cutting open dead children may have been a lot less common (and perhaps distasteful). If you did find something there, you would not assume an important organ present in a child and essential for their immune system would shrink and almost go away.
It would be more likely to be labelled nothing, an abnormal growth, or even a cause for death or illness (pressure on the heart/lungs!).
dekhn
The thymus is amazing... I ignored it for a long time then saw an amazing seminar. The thymus plays an important role in training the immune system: it expresses cells similar to cells all over the body, and then "educates" T-cells to avoid attacking those. Failures of the thymus often lead to autoimmune disorders.
bregma
I dunno. Comparative anatomy was a thing then and the anatomist may even have been fond of sweetbreads. They were still popular on menus in Paris when I was there a few months ago. It's possible they were more notable for their absence in adult humans.
twic
Although, as it happens, the thymus was known at least as far back as the ancient Greeks:
dennis_jeeves2
>my friend's favourite organ
Woody Allen's second favorite organ is the brain : https://www.youtube.com/watch?v=ngizj5FIcjo
nntwozz
The appendix also comes to mind, being told it was useless for so long and now evidence suggests it has important functions for the immune system.
jac241
Maybe, but I think more likely is the time factor for med students. There’s really only time to find the major structures implicated in disease. Surgeons also not likely dissecting around the clitoris much. Wouldn’t want to risk injury obviously.
FrustratedMonky
I also think it is great to call out that not all 'missing' things like this are a conspiracy, it is just inefficiencies, or competing goals of different groups.
"No shadowy Illuminati group deliberately made this decision, but as a civilization we have collectively ‘decided’ that three groups of people would get to peer inside the human body, and they’d all be hobbled."
elric
Oh indeed, I don't think there's a shadowy cabal suppressing the knowledge of the existence of our third eye or anything like that. But in the past, the long arm of the catholic church certainly had a chilling effect on some research.
Like the guy who built some of the first microscopes and discovered the sperm in semen, he wrote to the scientific community to discuss the discovery, but made sure to include that the semen he used was "what was left" after he copulated with his wife. Wouldn't want to give anyone the idea that he had masturbated, heaven forfend!
stefantalpalaru
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valval
You’re looking at this from a point of view with inherent bias, that has no guarantee of being lesser in degree than the ones that produced the literature.
chowells
You're looking at this from the point of view that bias is inherently bad. It's not. Biases do not need to be "lesser in degree" to allow adding something new to a conversation. They only need to be different from existing ones.
You know, diversity improves results.
elric
Hmm, I spent some time thinking about this comment, and I still don't get your point. Does my bias invalidate my claim? I mean I don't have any hard evidence that this is happening, but from a historical point is makes sense to me. If you disagree, it would be helpful to point out why, rather than to call out my bias.
MattGaiser
If I understand his three groups correctly, he’s basically saying that one of the big bottlenecks is that nobody is looking full time.
Basically, nobody has the job of discovering human anatomy except as a side hustle or byproduct.
I’m quite surprised at that. That’s a remarkable area to not have full time researchers in.
MikeTaylor
It's amazing how much science just gets no funding to speak of. There are maybe half a dozen museums in the world whose palaeontology departments are not in a permanent budget crunch. There is no money to fund digs, to find new fossils. There is, critically, no money to prepare fossils out of the rocks. One very major natural history known to me had only a single preparator on staff: and the last I heard, that one preparator had been let go so that no fossil preparation at all was taking place, at least officially. And of course there is no money to fund actual research into the fossils that should be coming out of those rocks -- for example, dinosaurs, which you'd think would be a big win for any ambitious museum.
The part of this that baffles me is that there always seem to be untold billions to build particle accelerators. Spread the wealth, high-energy physicists!
MattGaiser
I would have thought palaeontology one of the flashier topics.
Validark
It's sad to think about how little of our resources are dedicated to work like this. Although I enjoyed the Marvel movies growing up, it would be nice if similar funding could be found for a project like the author describes (and, of course, you could have a sort of documentary showing people what they discovered).
amelius
I think he missed at least one group: pathologists.
twic
Is it? How would anyone make money or fame out of it?
The way our scientific establishment works now is that you are rewarded for discovering things which fit into and shed new light on our existing web of understanding, not for things which are completely new and unconnected. I don't think this is entirely bad - science is useful because it's a densely connected web rather than a bag of unrelated facts. But it does mean that very little value is attached to observations of weird new things that don't fit in anywhere.
Back when I was a scientist, I was studying a known structure in the cytoskeleton. By chance, some of the cells I prepared went funny, and produced a radically different structure that I hadn't seen before, and couldn't find any mention of in the literature. I showed my supervisor, who basically said "so what?". On their own, this new structure was useless to a career scientist, because you can't say anything about what it is, what it does, why it's important, or how it connects to what anyone else is publishing about.
(It turned out this structure had been seen before, and published a few times, but still, nobody really knows what it's all about)
MattGaiser
> But it does mean that very little value is attached to observations of weird new things that don't fit in anywhere.
This surprises me (as a non-scientist). As the observation is clearly real and clearly fits in somewhere to the web (the human body works after all), so it is just not valuable because it cannot easily be published without additional work?
> because you can't say anything about what it is, what it does, why it's important, or how it connects to what anyone else is publishing about.
I guess I am mostly surprised that "it exists" is insufficient. Or that the discovery of this new thing wouldn't trigger further investigation rather than "so what?"
btrettel
I just skimmed the article, but it reminds me of something from my own PhD in fluid dynamics. I worked in liquid jets/sprays, basically, when a stream of liquid flows from a nozzle and breaks into droplets. Nearly everyone has seen this in some form.
I published a "regime diagram" improving the existing categorization of types of liquid jet breakup. There were a lot of changes from the status quo, but one that strikes me as particularly sad was the addition of a new regime that I called "turbulent Rayleigh". Every time men pee, they create a turbulent Rayleigh liquid jet. Yet this was a mostly foreign concept to spray researchers! You can find a few papers that identify what they view as an anomaly, but the papers seem to be mostly ignored and they don't go beyond saying something like "Something here is weird, future researchers should look into this". I did my share, making a theoretical model of the regime, showing how it's fundamentally different from the conventional laminar Rayleigh regime. Most spray researchers would consider a "Rayleigh" jet to be inherently laminar, but that's a misconception.
The reason why this happened is that liquid jet/sprays research is heavily biased towards fuel sprays, which rarely ever have this regime. You basically need a long tube (or something similar) to reduce the Reynolds number for turbulence to appear, which usually doesn't happen in fuel spray nozzles. Fuel sprays tend to have lower surface tension and higher viscosity than water/pee too, which makes seeing a turbulent Rayleigh jet even harder.
CoastalCoder
Ok, honest question:
Is this why guys have so much trouble peeing only into the toilet bowl when standing?
btrettel
That's a problem of aim, not spray formation, and thus beyond my expertise. The Rayleigh regimes produce large droplets (mainly diameters similar to the orifice) and not a finer spray that could go everywhere.
Also: Peeing into only the bowl won't necessarily minimize the mess. Air gets "entrained" into the water and that creates splatter. Best practice is to target the porcelain inside the bowl (just above the water line) and adjust the distance so that the stream has broken up less as droplets will create more splatter than a solid stream.
saagarjha
You could also sit down.
mandmandam
There are different reasons for this.
The biggest one is that many guys are just vile. Sad but true. They don't even try to aim, because someone else will clean it; and they don't even wash their hands after.
The next biggest is that sometimes where you point isn't where the stream goes, whether from a random pinch in the tube or a proprioception error.
And sometimes the stream is split, and it's not entirely predictable when that will happen.
Spray?? Never had an issue like that. Can't speak for everyone though.
xboxnolifes
To add to the other responses: sometimes it's splash-back from the bowl water itself. It's gotta be toilet bowl dependent, and I assume some people are just too lazy to clean theirs up.
Unbefleckt
I'm genuinely curious as to why this is, as someone who has never had trouble aiming or covered the seat in piss.
roca
The incredible complexity of anatomy is even more amazing considering
* all the structures grow from a single cell
* somehow it's all encoded in DNA (only 6 billion bits in humans, which has to also build cells and their ultracomplex machinery)
* this all had to evolve using only a very noisy objective function
semitones
I wonder if saying that "it's all encoded in DNA (which is only 6 billion bits)" is accurate. Every time life (considering only humans for now, to simplify) arises, in addition to the DNA (the "code"), you also have the rest of the first cell (the zygote), which already has an "expression" of that code (which may contain additional information beyond what is already in the code), + the entire environment of the mother (which obviously provides additional information).
This makes me think that we need far more than just 6 billion bits to actually encode the entire process of new life formation (each instance always piggy-backs off the previous, and always provides processes/information).
moi2388
You might want to look up Dr.Michael Levin.
He is studying exactly this. He found that when developing, cells move and grow in a particular direction. But when an obstacle is placed in their way, they move around it to somehow still end up where they’re supposed to.
DNA is not all of the encoding. Even cells appear to have some form of navigation or space search capabilities.
fellowmartian
His work is mind-blowing and completely upturned my perception of biology.
doctorpangloss
Why do miscarriages occur? They are frequent, so they seem to be an essential feature of pregnancy.
cultofmetatron
I imagine from an evolutionary perspective, a false positive of the fetus bringing harm to the mother is preferable over the long term for increasing long term reproductive survival.
im3w1l
Miscarriages must occur because our DNA is constantly mutating. Some of those mutations will be so harmful that the new organism cannot even survive until birth.
In addition to those unavoidable ones, there can also be things going wrong by accident (e.g. the pregnant woman suffer physical injury which kills the fetus).
pas
lack of immune tolerance in the mother.
for example (pre)eclampsia. we still don't know WTF is going on exactly (but it's basically abnormal blood vessel formation between the fetus and the uterus), and a few decades ago it was basically guaranteed loss of the fetus or the mother (or both), in about half a percent of pregnancies.
nowadays thanks to medical science it's a hundred-times more manageable.
candiddevmike
The fetus's liveliness check failed
codesnik
chemical gradients?
rolisz
Michael Levin has some awesome experiments where he screws around with the bioelectric fields of planetaria and he gets them to grow two heads and no tail, while being genetically identical to a normal one.
elric
One of my old classmates' area of research is applying electric stimuli to various types of cells. Apparently the right amount at the right time can briefly allow foreign material to pass through the cell wall unimpeded. The complexity of a single cell is insane, that of a complex organism is way beyond insane.
dennis_jeeves2
I think you meant cell membrane rather than cell wall?
(There is a contrarian theory that says that the cell membrane does not exist at all, look up Gilbert Ling. So it's no surprise that things can move in and out of the cell under certain conditions.)
inglor_cz
Planaria. (Yeah, I am a pedant sometimes.) Also, frogs, tadpoles, axolotls. Truly a wonderful mind. I admire him, not least for his ability to do really weird and important science outside the usual "don't do anything extraordinary" boundaries set by ossified grant committees.
rolisz
facepalm Thank you. That was not pedantic at all, I made an early morning mistake.
Gooblebrai
I thank you. I was looking for planetaria and I was confused
dmd
And you keep them in the planetarium, right?
wolpoli
You are telling me that we do not have a way to clean build human from DNA source. That's a real continuity risk.
heckelson
The battle for reproducible builds continues
Aerbil313
We need purely functional nanomachinery to create every embrionic molecule from element atoms, and a declarative physical language to combine them in the right way to create a zygote.
emptiestplace
What if, as human consciousness is an emergent property of complexity, so too are humans and DNA itself? Could it be that, just as consciousness arises from the intricate networks within the brain, life and its fundamental components—like DNA—emerge from an even deeper layer of complexity in the universe, suggesting that our very existence is a product of systems far beyond our current understanding?
thfuran
I'm not really sure what you mean. Complex biological molecules are emergent from the laws of physics and an environment containing the right precursors.
gcr
If true, alien first contact scenarios get a lot more interesting.
Someone should write a short story about that.
bgun
We do, but it’s messy and usually involves a few years of courtship, followed by one to three decades of raising & educating the resulting human to anything resembling a useful model for comparison.
gcr
No, the claim is much stronger than that: that the zygote itself encodes necessary information that isn’t captured in DNA. Put another way, long after humans are extinct, the claim is that if aliens could download our DNA source code somehow, they still wouldn’t be able to build humans without replicating the zygote’s internal structures exactly. We’d come out as super deformed or something.
The claim is biological, not sociological.
Thiez
Perhaps the first generation would be deformed but second-gen (if they hypothetically get that far) should be much closer. You still need the mitochondrial DNA as well.
tsimionescu
Well, first of all, they wouldn't be able to build a single functioning cell if all they had was DNA (and even if they had mitochondrial DNA too). Most organelles divide independently of the nucleus, and there is no reason to think that DNA encodes anything about their fundamental structure. Even if some changes in genes can effect some changes in the organelles, that doesn't mean that the genes specify every detail of the organelle.
Also, even if we accepted that DNA fully specifies how a cell can create an identical copy of the cell that contains it, that doesn't mean that it specifies how to create a cell from scratch. The "instructions" in DNA could very well depend critically on details of the current cell. For example, the DNA could specify se thing like "take 1% of the substance secreted in organelle A and mix it with 90% water and 9% the substance secreted by organelle B". This instruction is perfectly good for specifying a copy of the current cell, and perfectly useless if you don't have the original cell for which it is meant.
This sort of thing could very well apply at the level of the whole fetus. Details of the uterus and other parts of the mother organism may well be critical parts of the "program" described by the DNA. For example, it's easy to imagine that the early fetus follows instructions like "let this much fluid pass through the umbilical chord", or "grow horizontally until you find this much pH difference between the extremeties" or whatever other instructions that are only useful in the context of an existing functioning mother organism.
And even beyond the individual, you would have a big problem recreating the species to allow for a second generation to exist at all. In particular, even if you had a whole living healthy female mammal, you would have no information at all for how to create a male of the species, so no way to create sperm cells, so no way to perpetuate the species. So the DNA of a female mammal doesn't contain information for how to make more of the species. And if all you had was a male organism, you would lack the information probably encoded in the living female that I was discussing earlier.
As a side note, this problem would not exist for birds, where the female bird does have both male and female DNA.
shepherdjerred
e.g. imagine being given some source code and being told to compile/execute it but you're not given any hardware.
tsimionescu
Not only that, but you're not even given the compiler. If all you have is the DNA (even if you had the mitochondrial DNA too), you have source code for a language no one knows with no compiler.
Or, more accurately, it's like having binary machine code for an unknown ISA with no information about the CPU, and no example CPU.
ekimekim
Well based on compiler bootstrapping techniques, it seems the solution is simple: Start by hand-assembling the most basic RNA life, then run each step of evolution in sequence. All you need is the DNA (and know the living conditions) of every single organism between single-celled organisms and a modern human.
delecti
I mean, is that really true when the "we" is a group of 8 billion, about half of whom at any time can contribute to a build server?
bregma
Mathematically it's true. Anything that can be enumerated (that is, has an ontological mapping with the set of whole numbers) can be interpreted as input to some function which can be evaluated to some result also with an ontological mapping with the set of whole numbers. In other words, the entire human population could be a part of some program calculating the answer to some universal question, which may be about life, the universe, and everything. In fact, the answer may already be known. We're just one big server with massively parallel operation.
What we don't know is what that function is. Put differently, what is the question?
admissionsguy
> you also have the rest of the first cell (the zygote), which already has an "expression" of that code
It's called maternal effect (https://en.wikipedia.org/wiki/Maternal_effect)
tsimionescu
I think they meant something even more basic, and common to all cells: you can't make a new cell without an existing living functioning cell. We have no firm idea of how the first cells developed, but all of the cells we know of today come from the division of another cell, and we have never observed anything remotely like a new cell forming pit of a puddle of all the required substances and DNA.
joshuahedlund
Yes, I recently read the book The Master Builder by Alfonso Arias which gets into some of the detailed pre-requisites provided by existing cells. (it’s also why restoring extinct species may be harder than expected even knowing their full genetic sequence)
TZubiri
Disclaimer. I'm not a great biologist.
Couldn't this be proven by growing mammals in petri dishes?
If the entire information is encoded in DNA, then the fetus would grow fine.
If however, the fetus needs to be in a womb to develop, then there must be information (and resources) that need to be sent from the mother to the baby in a sort of quine fashion.
Consider a Java compiler or python interpreter, they are themselves written in the target language, unless we are talking about early version. So you already need a java compiler to compile Java, the code for the compiler does not hold all of the necessary information, as you need a mother compiler to execute it.
Which part of the target is in the code and which in the interpreter/compiler?
A thought experiment would be a language where a built in statement compile() compiles code according to specifications. Thus the code for a compiler would simply be compile().
My best guess is that fetuses can only grow inside a functioning human, and that the information in DNA is not sufficient, you need a functioning specimen to grow another specimen.
dekhn
https://en.wikipedia.org/wiki/Maternal_effect The egg contains mRNA or protein created by the mother that affects the child's phentotype.
It's unclear how much those non-genomic components affect organismal phenotypes; presumably, there is some minimal collection of factors that would suffice to allow us to construct an artificial egg cell that is viable for reproduction.
roca
This is a very interesting observation. I wonder if there's a way to identify the contribution of that initial cellular environment to the phenotype. I guess you could do experiments where you tamper with the initial cellular environment or the DNA and see what happens.
thfuran
At the very least, epigenetics are also partially heritable.
tialaramex
> only 6 billion bits in humans
A 27-state two value Busy Beaver can implement "Give a counter-example to Goldbach's Conjecture" - if there are none the program never halts. We can recognise that, and say "Oh dear" but it gets us no closer to an answer. Six billion isn't even in the right ballpark, our ability to understand the meaning of every self-acting machine extends maybe to six or seven bits if we're very smart.
9dev
I wonder if it's actually more similar to procedural generation, based on a seed value, that reliably recreates the same complex output that isn't entirely described by the seed alone. In this case, the DNA would just serve as input to a myriad of algorithms that yield a fully working cell. A single base pair change may lead to a mind-bogglingly long chain of side effects that result in a third arm, or really just nothing at all.
refurb
> somehow it's all encoded in DNA (only 6 billion bits in humans, which has to also build cells and their ultracomplex machinery)
One has to be cautious to not assume that the only data DNA holds is in base pairs.
We know that secondary factors like inter- and intra-strand interactions or DNA-histone interaction encodes information as well.
A good analogy is a book. While it is made up of individual letters, the combinations build to words, which build to sentences, which build to ideas, which can interact with other ideas (sometimes in other chapters!) to create a complexity beyond just the combination of letters would suggest.
That's not even getting into the temporal aspects of DNA expression.
candiddevmike
I believe DNA is a compression algorithm beyond our current understanding, and the 6 billion bits is a post-compression size.
wonnage
I don’t think it’s true that DNA actually encodes an entire organism. Leaving all discussion of epigenetics aside, the proteins produced from DNA can basically do anything, including modifying DNA. Maybe we could think of large portions of DNA as simply bindings to shared libraries (i.e, the proteins). Or like a package manifest and build script for life rather than the code itself
lubujackson
A crappy, self-improving function with a decent feedback loop (survival) can get pretty far given 100s of millions of years with hundreds of million (or trillions) of concurrent experiments running at the same time. The time scale of life is the hardest element to comprehend.
dotancohen
> only 6 billion bits in humans
lostlogin
> compact disc
It’s probably not far off being easier to read DNA than a CD. And it’s surely less frustrating.
thih9
> 6 billion bits in humans
~750 megabytes (unit conversion via google)
BurningFrog
> all the structures grow from a single cell
Two cells: Egg and sperm
yjftsjthsd-h
...which merge into a single zygote cell.
Metacelsus
A fertilized egg (zygote) is one cell.
aconz2
Bit late and I posted essentially this same comment on their site in hopes they'll see it, but this article jumped out at me because a while ago I was thinking about what it would take to get a whole organism single cell atlas so that you could explore it on the computer. The only thing I can really think of is to take a CNC machine, put it in a big freezer, then scan one layer of the specimen with a microscope and whatever multispectral lighting/imaging you need, then mill away a layer and repeat. Pathology slides are prepared with stains to enhance the contrast of membranes and other features which is probably not an option in the frozen state, so that's a big hurdle, but maybe you can do it with some fancy multispectral imaging. And if you can't, maybe you can at least start with lower resolution structures like anatomy (though I think there's still contrast challenges for that). I know there are some single cell atlas efforts for parts of or whole brains for mice and maybe other organs, but like the author's dream idea of getting order thousands of specimens to study variation, it would be great dataset if you could capture everything in one go.
kaikai
This exists! They’re called knife-edged scanning microscopes.
aconz2
Wow thanks for the info! This was a good overview of one system https://academic.oup.com/mt/article/25/4/14/6815410 - 5um slice thickness at 0.7um per pixel and ~1 TB/cm^3, max sample size 50x50x20mm. Humans are about 75k cm^3 so a 75 PB scan isn't impossible. Probably start with a coarser scan and work on the compression algorithms. "Just" need a (much) bigger scanner. And figure out if the knife edge is okay with bones!
verisimi
This is a great case study in how all science is hobbled.
Define categories, silo information - who will ever recognise something unusual under their very nose?
11235813213455
I think human species real advantage is human hands, they are so precise, for me that's what made the difference
fooker
Human hands are marvelously complicated, we don’t appreciate that much as we see our hands everyday.
Interestingly, a stark reminder for this came when image generating models could generate everything except realistic hands.
everybodyknows
Hands are notoriously difficult for human artists to draw as well; this is perhaps one reason so few make the attempt nowadays.
FredPret
And living above ground. Whales and octopuses might be geniuses but they'll never have a tech tree because they can't melt metal
inglor_cz
I sometimes wonder if crows would be able to build a civilization if they had human hands.
They may be about as smart as australopithecus, so there could be an evolutionary feedback loop: tools-brain-better tools-better brain.
But you can only do so much with a beak.
out_of_protocol
Crow's brains are very good at what they do because their version of human's neocortex is in the center of the brain. And this is the reason why crow's brains can't scale up, there no enough space to grow "thinking" part of brain
hinkley
In the Uplift books dolphins are given prosthetic arms. That’s already half future tech and you’d have to miniaturize them for crows. No way to control them yet, in either case.
ghthor
[flagged]
atombender
I'm not sure what you mean by this comment. Was there a time when you didn't have hands?
11235813213455
yes, when we were still bacterias or a bit later, even monkeys hands are not always super precise
keepamovin
The author says that no one‘s gonna fund such work, but I really think the stated multibillionaires should fund it.
biological anatomy makes it pretty clear that biological bodies are complex layering of biopolymer sheets that perform incredible mechanical, biochemical and other subtle energetic processes.
We could learn a lot about the robots we hope to build by intricate studies of how Animal anatomy has really perfected the art of efficient and compact mechanical motion and advanced functions.
In a sense, the sophistication of the dense layering is akin to how modern processor architectures, motherboard and fully integrated circuits SOCs inside compact devices are kind of composite materials of fused layers of nevertheless separate components.
I believe this kind of work really should be funded.
jamesy0ung
Link seems to be broken, Firefox is displaying raw JSON when I visit it.
jraby3
It’s working for me.
davorak
It did not work for me either, in chrome.
The follow link work though: https://svpow.com/2024/09/07/
dwighttk
Ant that’s just the structures, next is the purpose
aaron695
> If I was a multi-billionaire, I’d hire 1000 of the world’s best surgeons <> supply them with 10,000 ethically donated willed bodies
No, this would be like like giving the best programmers super computers in the 80's.
What's needed is a better way of doing anatomy. The tools and access are the problem.
One cadaver x-rayed and MRI'ed and ultra sounded in great detail then the raw data shared for free for instance.
Or do what really really matters and is also the end goal, a cheap way to see inside the living. Cheap ultrasound chips with open data APIs so people can try and find ways to increase accuracy for instance. Every farmer should have an ultrasound but they are too $$$
s5300
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dannyxertify
There is still too many things to be discovered and hope AI will give us a full understanding of it
As part of an NIH consortium I work with two teams that are collecting multi-scale anatomical data on the human vagus nerve with one of the objectives being to start to get a handle on the variability between individuals. The variability that the experimental teams are seeing is beyond anything I expected, though admittedly my assumptions were naive. The branching structure and routing of the nerves is basically unique per human and we are in the processes of determining whether there are invariant rules (e.g. for branch ordering) that apply across all individuals. And that is at the level of gross anatomy. So we aren't even done with gross anatomy, despite many biologists thinking that the foundations are complete and have been since the 16th century. Turns out that if you want to be able to apply our knowledge of gross anatomy for more complex clinical use cases we need significantly more data about basic variability in structure so that we know what additional data we need to collect for each individual.