The Brain Is Actually Two Completely Separate Organs (stanford.edu) 68
"New research led by Stanford Medicine reveals that what we call the brain is two distinct organs that evolved independently over hundreds of millions of years," Stanford Medicine announced this week:
The new research finding shows that the human brain consists of two ancient nervous systems cleverly packaged together — a more primitive part that regulates our hearts' beating, our breathing and other functions, and another that makes us distinctly human, capable of poetry, mathematics and wondering about our own origins. The discovery could help explain why scientists have struggled for decades to grow certain types of brain cells in the laboratory — and it opens new avenues for studying devastating diseases that affect the brain stem...
[S]cientists have struggled for decades to generate human hindbrain neurons in the laboratory. This gap has hampered research into devastating diseases affecting the brain stem, including spinal muscular atrophy and amyotrophic lateral sclerosis... The researchers' breakthrough came from studying the earliest moments of embryonic development... [Study co-authors Carolyn Dundes and Rayyan Jokhai] discovered that the hindbrain follows a separate developmental path, running in parallel to — rather than branching off from — the pathway that creates the forebrain and midbrain... This revelation explained decades of frustration in the field — scientists had been trying to turn one type of progenitor cell into another that it is fundamentally incapable of becoming... Armed with this knowledge, the researchers for the first time successfully coaxed human pluripotent stem cells (a kind of cell that can create any cell in the human body) to become functional hindbrain motor neurons in the laboratory...
Finally, the researchers looked back over 550 million years of evolutionary time. They found the same two-origin brain pattern in chickens; zebrafish; and, remarkably, in acorn worms, tiny creatures living on the ocean floor that share a distant common ancestor with humans. Jellyfish, which diverged from humans about 600 to 700 million years ago, have two nervous systems at different ends of their body. "Our research suggests that evolution took two existing neural systems and pushed them together spatially," Loh said. "Having the brain as one organ would probably be more efficient, but we rely on this primordial way to make the brain as two separate pieces."
Thanks to Slashdot reader Beeftopia for sharing the article.
[S]cientists have struggled for decades to generate human hindbrain neurons in the laboratory. This gap has hampered research into devastating diseases affecting the brain stem, including spinal muscular atrophy and amyotrophic lateral sclerosis... The researchers' breakthrough came from studying the earliest moments of embryonic development... [Study co-authors Carolyn Dundes and Rayyan Jokhai] discovered that the hindbrain follows a separate developmental path, running in parallel to — rather than branching off from — the pathway that creates the forebrain and midbrain... This revelation explained decades of frustration in the field — scientists had been trying to turn one type of progenitor cell into another that it is fundamentally incapable of becoming... Armed with this knowledge, the researchers for the first time successfully coaxed human pluripotent stem cells (a kind of cell that can create any cell in the human body) to become functional hindbrain motor neurons in the laboratory...
Finally, the researchers looked back over 550 million years of evolutionary time. They found the same two-origin brain pattern in chickens; zebrafish; and, remarkably, in acorn worms, tiny creatures living on the ocean floor that share a distant common ancestor with humans. Jellyfish, which diverged from humans about 600 to 700 million years ago, have two nervous systems at different ends of their body. "Our research suggests that evolution took two existing neural systems and pushed them together spatially," Loh said. "Having the brain as one organ would probably be more efficient, but we rely on this primordial way to make the brain as two separate pieces."
Thanks to Slashdot reader Beeftopia for sharing the article.
Not quite ... (Score:5, Interesting)
It's been known for a while that the nervous system of animals started out as separate front/sensory and rear/motor+autonomic-functions, and in humans we see the same gene expression markers in front/back (fore/midbrain vs hindbrain aka brainstem) as we see in primitive animals such as the acorn worm where these remain far more separate.
What this new research shows isn't that our brain originated as two organs/systems, but rather that it still goes through that stage during embryonic development rather than having been more fundamentally fused into one earlier in our evolutionary history as had been believed to be the case.
It's yet another case (cf human embryo having a tail, chicken embryo having teeth) of "Ontogeny recapitulates phylogeny" whereby embryonic development does through the same steps as evolution did.
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Your comment is interesting but "Ontogeny recapitulates phylogeny" is discredited. I am not an evolutionary scientist, but I can run and understand Deepseek, so apologies if I am being taken in by AI slop, but here is the text of my conversation with deepseek, which I find convincing.
Please refute this refutation if you can!!
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You're confusing Ernst Haeckel's original theory of "Ontogeny recapitulates phylogeny" as a "law" (false), with the reality that embryonic development nonetheless does expose some of our evolutionary past.
e.g.
When chickens evolved from dinosaurs they lost their teeth, but they didn't lose the dinosaur DNA that creates teeth - what changed was gene expression controlling embryonic tooth development and sequencing. You might have expected that evolution would have just disabled development of teeth altogether
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Yes, but it only mentions it as a case study in what NOT to believe, and points out where it is wrong.
Which seems reasonable.
Re: Not quite ... (Score:5, Informative)
Stop cut and pasting AI slop you moron, it doesnt make you look smart. We re quite capable of quizzing an LLM ourselves.
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Millions of litres of water usage. Megawatts of power usage, thousands upon thousands of tonnes of carbon output. Destruction of habitats and consumption for decades and decades of land under a cement slab full of compute hardware with next to no recycle/upcycle pathway, the cost and demand of which is making it next to impossible for a good chunk of the world to upgrade their personal computational devices. All so you can demand a bunch of humans who actually know, if this nested if/then/else statement tha
Re: Not quite ... (Score:4, Funny)
tl;dr: my video card got more expensive so now i hate AI.
Re: Not quite ... (Score:2)
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C'mon - I asked the question - is this AI slop or good stuff. There still seem to be some experts on here and I want their considered view.
Nobody's going to read it, expert or not. It's a wall of... whatever. It's not written or formatted in a way that is enticing to a reader.
Remember... LLMs regurgitate materials that already exists. People who are familiar with the topic likely already know anything accurate or factual in it. People who aren't familiar with the topic could go somewhere reliable to ingest the facts. This unsolicited pile of words... serves nobody.
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I read it and found it interesting. But then again I don't know much on that subject and thus can't pick out fact from fiction. But then again if someone had typed that in their own words I still wouldn't be able to pick out fact from fiction.
In terms of a waste of resources, yes it is. However it's something someone looked up on their own and then decided to share it here. That means other people don't also need to look it up.
In summary, I'm fine with that type of post so long as it identifies itself a
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I read it and found it interesting. But then again I don't know much on that subject and thus can't pick out fact from fiction. But then again if someone had typed that in their own words I still wouldn't be able to pick out fact from fiction.
Basically, it isn't fiction per se, but is pretty much meaningless. Nobody thinks that "ontogeny recapitulates phylogeny" is an "evolutionary advantage". It just demonstrates that we come from a process of evolution where we are changed forms of our direct evolutionary ancestor, they are a changed form of theirs, and so on back to our very earlier ancestors. If you take the tree of life and the set of nodes in it back all the way, that path through is our evolutionary line (mostly, anyway, there are other m
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You apparently asked stupid questions. No one was arguing that embryonic development passes through adult, fully formed versions of the traits of our evolutionary ancestors. Also, no one was arguing that it's some sort of evolutionary advantage. What it actually illustrates is that evolution is an iterative process of building on and modifying what has come before, which is well understood. It's like the idiotic "why haven't men evolved away nipples?" question. You jumped in to "debunk" something that no on
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? "Ontogeny recapitulates phylogeny" is not an evolutionary advantage. It is a biological hypothesis
I wouldn't even call it a hypothesis, and I'm not aware of anyone ever saying it was an "advantage" (advantageous for what?!).
Still, it is an interesting reality that some of our evolutionary past is preserved in our DNA and can be seen in this embryonic sequencing.
It's a reflection of the way DNA, gene expression, and embryonic sequencing, work, and the way evolution acts upon that.
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Re:Not quite ... (Score:4, Interesting)
All of science knew it - not just me! The acorn worm research is from 2003.
You're snarky response is misunderstanding what is new in this research - its not that our front/back brain correspond to the ancient front/back split nervous system, but much more specifically that they stay separate during early embryonic development - this is what is new information.
yw
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No one (mostly) is telling the people who actually study this stuff that they are wrong. They're saying that the headline is wrong about what has actually been shown here. The headline is just clickbait nonsense. The brain isn't suddenly revealed by science as two separate organs or any nonsense like that. There has just been an observation of structure during embryonic development.
Re: Not quite ... (Score:4, Interesting)
I am sorry, but your comment is completely wrong.
"Ontogeny recapitulates phylogeny" is a disproven theory. Human embryos do not have tails, chickens do not go through an embryonic stage where they have teeth. Your concept that this two-brain thing is a step in embryonic development is not what the article is saying.
Some years ago there was a very well-done and very popular drawing of human embryonic development showing a human going through evolutionary phases, and I too believed it for a while, but it was fantasy.
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Was it ever a theory? It's really just an observation. Although human embryos very definitely do have tails. I mean, you can call it something other than a tail if you want. Proto-tail, temporary tail, vestigial tail, etc. but it's clearly quite real and there. I think you might be conflating someone's exaggerated version of the concept with with the actual reality and rejecting the reality as a consequence kind of like people think that martial arts training doesn't make anyone a better fighter because the
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What this new research shows isn't that our brain originated as two organs/systems, but rather that it still goes through that stage during embryonic development rather than having been more fundamentally fused into one earlier in our evolutionary history as had been believed to be the case.
Ontogeny recapitulates phylogeny.
I still have a second brain at the other end (Score:1, Informative)
Re: I still have a second brain at the other end (Score:2, Informative)
Yes. "Cock-up" has had both of its meanings entrenched for a long time for a good reason.
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Yes, this is the scientific origin of the word "dick-head".
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It hangs in front of my balls and makes all my major decisions.
Obligatory John Hiatt lyrics:
Baby in my heart I'm faithful
This two headed monster is so distasteful
Forgive me when my instincts start stinkin'
I'm just so easily led when the little head does the thinkin'
Only two? (Score:5, Informative)
I thought this was common knowledge? The so-called "reptilian" brain and the "Paleomammalian" or limbic system of the triune brain theory made for some great pop psychology.
Interesting that it pans out on the actual cellular level, though.
I've always envied neurological researchers. Chopping up brains all day sounds like fun.
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Mod parent up, though you didn't do much to even guess how high the number might go. I've gotten quite a bit of data on related topics from Damasio's books, though his stuff is pretty hard to read. I also liked the way Jeff Hawkins approached the topic. (Too bad Mukherjee is unlikely to write a book on the topic.)
The chemical/hormonal sides of decision making are important. And all that vagus nerve confusion and crosstalk... Evolution is not teleological, but lots of genetic cruft just hangs around because
Re:Only two? (Score:4, Insightful)
Fascinating; three completely disparate things, none of which have any relation to teleology, the nominal subject of the sentence.
"Wigner's Friend" is a thought experment, pointing out that in a strict interpretation of quantum mechanics, even conscious observers must be in an indeterminate quantum state until observed by an external observer. The least action principle states that the path of an object moving through a potential field is the one in which the action, the time integral of the kinetic energy minus the potential energy, is minimized. The second law of thermodynamics says that in any closed system the change in entropy, defined as the change in heat divided by the temperature, must be greater than or equal to zero; for a not-closed system, in order to decrease the entropy in one place, energy is needed (typically to be radiated as waste heat; i.e., life takes energy from the sun, and rejects waste heat to the envionment (which ultimately radiates it to space).) None of these have any relation to teleology, the philosophical concept that causality is driven by purpose.
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Evolution is not teleological, but lots of genetic cruft just hangs around because there is no sufficiently strong incentive to remove it.
That is definitely true, but also raises an interesting point, we have also never evolved a mechanism to ruthlessly remove it for the small energy advantage it would give us. Part of that is because the threshhold conditions are too small, but another is that holding onto some of that old stuff as potential future building blocks might be an advantage in future evolution. Having mechanisms that drive a species into a non-evolving monoculture is almost certainly a genetic dead-end.
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These days I'm actually inclined to see it as running backwards, but after all that is sort of how evolution works. The "pressure" for new species is largely created when overspecialized species go extinct, thereby making available large "energy pools" that are no longer being exploited "efficiently".
I think I mostly agree with your reply, though I think vestigial features can also be useful when conditions regress. I have read a book or two recently that was going more deeply into the modular part of it.
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I think we're pretty much on the same page with this. I think what we need to always remember about evolution/natural selection is that even the process itself is subject to natural selection. Adaptive behavior is itself a trait that can evolve like any other trait. Even to the degree that, while Lamarck wasn't exactly right, it actually really is the case that some environmental pressures will cause hereditary changes through generations through what I think we're still calling epigenetic factors. Usually
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You're appealing to Dawkins, but I think he would disagree with you. It's the teleology again.
However I think that there is confusion because a lot of things we now tag with the label "evolution", such as "social evolution" or "technological" evolution are absolutely Larmarkian. One of my slow books right now is called What is thought? where he goes into a lot of detail about how DNA encodes executable modules as tools for handling various aspects of reality... However I do think he's doing too much handw
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You're appealing to Dawkins, but I think he would disagree with you. It's the teleology again.
Not teleology, I'm still talking about an emergent system. It's just a question of what sort of characteristics end up having a lower chance of ending up as dead ends. Adaptability, including characteristics that improve evolutionary adaptability is a characteristic that helps avoid dead ends. The simple, middle-school version of evolution basically has a model where mutations occur at random. However we already know of systems where organisms have evolved so that at least certain mutations are promoted. Fo
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I think you'd be better off to write more briefly and with tighter focus. I put some effort into trying to figure it out, but decided some of it doesn't make sense and some of it is just talking about evolutionary modules. Just now halfway through What is Thought? where he is taking the position that much of human intelligence is encoded in DNA in the form of modules that worked for certain kinds of evolutionary challenges.
Re:Only two? (Score:5, Interesting)
The front/back split this research is about has nothing to do with reptilian vs human brain - it is about brainstem (back) vs rest (front), and reptiles have both parts combined just like us.
You have to go way back in evolution, to the pre-chordates, to find this mostly separated front vs back dual nervous system. In all the vertebrates, including fish and reptiles, the two systems are already combined (at least in the post-developmental stage).
You can still also see it in a few modern descendants of the pre-chordates such as jellyfsh and the acorn worm.
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> Perhaps... but I don't think any part of the brain stem is creating poetry.
That's not what it is saying - the two nervous systems are 1) the front part, originally just concerned with sensing, that has now evolved into our mid+forebrain, including our neo-cortex which is the bit creating poetry, and 2) back part, our brain stem (+spinal cord) controlling motor and autonomous (breathing, heartrate, etc) functions.
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You have to go way back in evolution, to the pre-chordates, to find this mostly separated front vs back dual nervous system. In all the vertebrates, including fish and reptiles, the two systems are already combined (at least in the post-developmental stage).
You can still also see it in a few modern descendants of the pre-chordates such as jellyfsh and the acorn worm.
What do you think of the article's "Jellyfish, which diverged from humans about 600 to 700 million years ago..."?
Is there an Ascii for eye roll? 8^O
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I don't think it is common knowledge in the way you describe, no. They're not talking about reptilian vs not-reptilian, and while it's true that's a pop-psy thing, it's not a "The brain is physically made up of this", merely a "The logic the brain uses to determine responses to things are..." thing.
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That seems to be a different definition than the one they're talking about. It sounds like they're talking about evolutionary origins, and the "reptilian brain" metaphor is talking about function...
They probably aren't exactly all the same cells of the body.
There's also the sympathetic and parasympathetic division. Again it's separation along a *different* dimension.
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The triune brain idea has been known to be false for more than 50 years. No self-respecting evolutionary biologist [sagepub.com] believes it.
Huh. (Score:5, Insightful)
...and another that makes us distinctly human, capable of poetry, mathematics and wondering about our own origins
Someone's never been to Oklahoma.
Inside you ... (Score:2)
Cool! (Score:1)
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Not quite -- you either learned there were two hemispheres of the brain, or you learned there was an older section of the brain and a more modern section. Both are true and I'm not sure which one you're mistaking for this research. What this discovery says is that the old and new systems are not the same brain, not the same cell types, not the same anything except in tight proximity to each other. It's a pretty big discovery and not something covered in the past.
Re: Cool! (Score:2)
but the CompTIA doctor+ test will still call it 1 (Score:2)
but the CompTIA doctor+ test will still call it 1
phones ripped this off (Score:2)
Three shortly (Score:2)
Hmmm (Score:5, Funny)
I'm wondering... (Score:2)
If, given sufficient knowledge of DNA, RNA, their interplay and chemical signalling, we could design a single brain that would be more effective.
the did not read the "the dragons of eden" (Score:1)
car segan summed all this up in the late 70s
Are They The Same In Both Sexes? (Score:1)
why didn't they just study a maga supporter (Score:2, Insightful)
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This is compelling. (Score:2)
The jokes just write themselves (Score:2)
Insert jokes about men thinking with their junk or Zaphod Beeblebrox.
nope (Score:2)
No, it's not.