The Brain Is Actually Two Completely Separate Organs (stanford.edu) 48
"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.
Re: (Score:1)
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
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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? "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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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
Re: Not quite ... (Score:3)
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
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".
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
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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
Re:Only two? (Score:4, 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.
Huh. (Score:4, 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)
This is compelling. (Score:2)