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They identified two different brain progenitor cells. One, which expresses a gene called Otx2, is destined to become the forebrain and midbrain. The other, which expresses a gene called Gbx2, is committed to forming the hindbrain. They showed that these two cell populations never overlap; they are mutually exclusive from the earliest stages of development.
Very cool. Never thought the brain could have two completely different ancestors
"Nervous systems are typically defined as networks of neurons that communicate across synapses. But Burkhardt’s lab found something unique in ctenophores: Beneath the animal’s outer surface is a nerve net (pink mesh in this 3D reconstruction) whose neurons are connected by continuous cytoplasm — but with no synapses between them. “I don’t think any other animal has a nervous system like that,” Burkhardt said. Because ctenophores are one of the earliest branches of the animal family tree, the finding indicates that evolution may have crafted nervous systems twice: in ctenophores, and separately in jellyfish and all other animals."
I think there is a better way: The colder something is, the less sweet it will taste. if you warm-up ice cream and taste how sickeningly sweet that soup is, you won't be having so much for a while...
I think that adipose tissue is the biggest criminal when it comes to unwanted hunger, since it produces hormones to make you hungry the moment you actually risk losing weight.
Not sure how much the digestive neurons are involved with hunger actually, I thought its role was more about telling you which foods make you nauseous so you won't eat them, or subconsciously register which nutrients various foods have so you'ld crave the ones compensating for shortages more.
I heard adipose tissue also retains hormones and fat-soluble pollutants, and losing weight sets them free and have to be dealt with by the body in other ways. Specifically, the hormones can cause mood swings, which some individuals have learned to react to with binge eating.
The peer reviewed publication is linked to from the press release. The press release's headline does somewhat overhype up the actual finding though. The actual finding is that different parts of the brain arise from different neural ectoderm progenitors, which explains why it’s so hard to get a forebrain neuron to behave like a hindbrain neuron and vice versa in the lab. The paper then postulates that this difference in progenitors resembles being two different organs evolutionarily, but this is not really the most important part of the paper.
BTW I suspect that this finding comes as completely unsurprising to biologists and the medical field generally. I'm not in either field, but even in high school biology we learned that the brain stem is behaviorally and structurally radically different from the rest of the brain, to the point where it seems almost obvious in hindsight that it's a different cell line and potentially has a different evolutionary history from the rest of the brain.
* Different brain regions have different functions: ancient knowledge.
* Different regions contain distinct cell types and molecular programs: also well established.
* Anterior and posterior brain structures may trace back to fundamentally separate progenitor lineages that were independently specified very early in evolution and development: that's the interesting new result.
The headline should have been: "Human forebrain and hindbrain arise from distinct embryonic progenitor lineages" - not that we have "two organs" in the brain.
Lying is always a bad choice. The paper in Nature says
"Hence, we postulate the brain is a composite organ emanating from two lineage-restricted progenitors; these dual progenitors may be evolutionarily conserved across 550 million years from hemichordates to mammals."
Given the parallel example cited in the article of jellyfish having two spatially separate organs, & the subsequent speculation that our own ancestors could also have had spacially separate anterior & posterior masses, the title doesn't really seem unreasonable in its hyperbole.
While it might not be perfectly accurate it's hardly misleading.
I found the title confusing, at the very least because it can be argued that the two brain hemispheres are two organs already, as they operate independently when severed from each other.
"Human forebrain and hindbrain arise from distinct embryonic progenitor lineages"
I'd have never clicked that headline nor understood why this finding is important.
If you think the original headline is not "truthful" enough, at least do something like "Researchers found the reason why hindbrain cells cannot be grown in a lab and found a way to overcome it"
not that we have "two organs" in the brain.
Depends what the definition of "organ" actually is. What speaks for different organs here is that the cells both have a different pathway from stem cells and have different evolutionary histories. That is different from other brain regions that may have separate functions but still evolved together.
I think it's less about what was said (it is truthful) and more what isn't mentioned in the title which leaves ambiguity.
I don't necessarily think it's intentional. For those with knowledge in the field I suspect it resonates the appropriate reaction.
For those outside of the field, I think the perception of what being 2 organs means does a lot of leg work in invoking a response which seems exaggerated, but is probably caused by incorrect assumptions of what the title is trying to convey.
I hope that makes some sense, I feel that was a lot of word vomit but I'm struggling to find the right words, it's somewhat meta
I don't have a problem with the 'two organs making one' framing. The fact that they are 'symbiotic' now doesn't change that. In fact it helps me understand two key facts. One can't grow out of the other, and they work differently. Great
Main issue I have with the title is it immediately reminded me about McGilchrist's "The Divided Brain" and I thought they meant the two halves - but that is not the case.
It's cool, but the headline is really pretty misleading.
The new result seems to be that researchers have identified different progenitors for fore/midbrain vs. hindbrain and have found that they can be identified by some specific developmental gene markers. That's genuinely cool.
However, organs are not typically defined by a single tissue characterized by a progenitor that can be labeled with a single gene marker. I suppose it's fine if on a functional and anatomical level you want to split the fore/midbrain and hindbrain into two different "organs", but whether you think of the brain as 1 organ or 2, it really doesn't change much in terms of how you would think about these regions.
It isn't at all surprising that different regions of the brain have localized functions; some of the earliest evidence of this was how focal injuries (like strokes) have characteristic deficit patterns depending on brain region affected, and obviously there has been a lot of work since then further showing the organization, function and development of different brain regions.
The really exciting thing in this article is that this research led them to a new technique for growing brain stem cells in vitro, which has been very difficult until now. If that isn't being oversold, it's big news. That's going to make future research into diseases like ALS a lot easier.
Title: "Two parallel neural ectoderm progenitors contribute to the developing brain".
"Hence, we postulate the brain is a composite organ emanating from two lineage-restricted progenitors; these dual progenitors may be evolutionarily conserved across 550 million years from hemichordates to mammals."
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.
I'm not sure the actual article in Nature Neuroscience [1] actually says that. I remember "Your Brain Is Not an Onion With a Tiny Reptile Inside" [2] from a few years ago, but I'm not sure where the dissonance comes from: my own misunderstanding, the press release using a popular but flawed model to communicate with laymen, or these two articles being in direct contradiction with each other?
What is the difference between saying that the brain is two organs, as in the title, or a "composite organ" as in the actual paper? What makes an organ a single autonomous organ?
The digestive tract could also be seen as a single organ since they are connected. I think the deciding criteria should be the one applied in this study, i.e., how an organ develops.
The cerebellum isn't just for motor skills. It's more of a place where very commonly used patterns get a bunch of dedicated wetware so the computation is superfast and precise. In an (undoubtedly very limited) analogy a bunch of FPGAs to complement the general processing. It does make a lot of sense to use this functionality for motor skills, though.
All the comments I see are about is it two organs, or a composite organ.
Surely the interesting thing is the ability to grow hindbrain cells in vitreo. That's what's potentially going to lead to the cure of lots of things, not whether 1=2.
I don’t think the medical community has believed as the article claims for nearly a century.
Most animal brains have three very different organs in the brain: the cerebrum, cerebellum, and the limbic system (which itself is further divided into numerous differentiated types of tissues)
that's funny when I was in junior school, 15 years ago, I said in the classroom during science class, that we have 2 brains. everyone including my teacher were laughed at me.
bioRxiv preprint July 2025 [0]
The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY 4.0 International license.
[0] https://www.biorxiv.org/content/10.1101/2025.07.02.662771v2
PDF is free to download.
Related https://www.newscientist.com/article/2589739-our-brain-evolv... https://news.ycombinator.com/item?id=49755533
Very cool. Never thought the brain could have two completely different ancestors
and from another post on the front page right now https://news.ycombinator.com/item?id=49735541 :
"Nervous systems are typically defined as networks of neurons that communicate across synapses. But Burkhardt’s lab found something unique in ctenophores: Beneath the animal’s outer surface is a nerve net (pink mesh in this 3D reconstruction) whose neurons are connected by continuous cytoplasm — but with no synapses between them. “I don’t think any other animal has a nervous system like that,” Burkhardt said. Because ctenophores are one of the earliest branches of the animal family tree, the finding indicates that evolution may have crafted nervous systems twice: in ctenophores, and separately in jellyfish and all other animals."
Funny thing when reading that is as a human I read „crafted nervous system twice” like it would be done over a week or two.
We fail to imagine how much time takes to „craft a nervous system”.
Super scary how small are we in big scheme of things.
I think the fact that the sentence says we share the nervous system with jellyfish gives a good indication of that.
https://learn.genetics.utah.edu/content/senses/eye/
at one point I learned that it would only take a few hundred thousand years to evolve an eye, and time felt much deeper.
Fun fact: the hindbrain progenitor cell is shaped like a little lizard.
The lizard brain, not because it resembles the brain of a lizard, but because it's made up of a trillion tiny lizards
Why would it be surprising?
All parts of the body are built like this. Otherwise we would be blobs.
Before becoming two parts they probably were part of the same parent protobrain tissue.
If you told me the hindbrain was ectoderm-derived but the forebrain was endoderm-derived, I might raise an eyebrow or two.
We are going to have to deprecate an idiom or two. "I'm in two minds about something" now gives the wrong meaning.
Not to mention the gut brain-- That's the organ I blame for the ice cream I just ate
The best way to stop eating ice cream is to stop buying ice cream. If it's in the freezer, it'll be eaten.
I think there is a better way: The colder something is, the less sweet it will taste. if you warm-up ice cream and taste how sickeningly sweet that soup is, you won't be having so much for a while...
But how do you stop buying ice cream?
You buy your groceries while that piece of your brain has no excuse to make loud demands ;-)
Eat your dinner before going to the shop.
Fill your freezer with frozen food other than ice cream.
I think that adipose tissue is the biggest criminal when it comes to unwanted hunger, since it produces hormones to make you hungry the moment you actually risk losing weight.
Not sure how much the digestive neurons are involved with hunger actually, I thought its role was more about telling you which foods make you nauseous so you won't eat them, or subconsciously register which nutrients various foods have so you'ld crave the ones compensating for shortages more.
I heard adipose tissue also retains hormones and fat-soluble pollutants, and losing weight sets them free and have to be dealt with by the body in other ways. Specifically, the hormones can cause mood swings, which some individuals have learned to react to with binge eating.
This isn't peer reviewed, just a press release. 10 other "papers" will be published in the next 2 weeks counterfinding anything in this post.
Science moves forward yet again with a few backward steps.
Here is the peer reviewed publication in Nature Neuroscience:
https://www.nature.com/articles/s41593-026-02433-7
The peer reviewed publication is linked to from the press release. The press release's headline does somewhat overhype up the actual finding though. The actual finding is that different parts of the brain arise from different neural ectoderm progenitors, which explains why it’s so hard to get a forebrain neuron to behave like a hindbrain neuron and vice versa in the lab. The paper then postulates that this difference in progenitors resembles being two different organs evolutionarily, but this is not really the most important part of the paper.
BTW I suspect that this finding comes as completely unsurprising to biologists and the medical field generally. I'm not in either field, but even in high school biology we learned that the brain stem is behaviorally and structurally radically different from the rest of the brain, to the point where it seems almost obvious in hindsight that it's a different cell line and potentially has a different evolutionary history from the rest of the brain.
I thought the PR article did a decent job or saying just that, except maybe for the title
Yeah, agreed. It's mostly just the title that is overhyped.
no idea what you're talking about.
watson and crick's paper was not peer reviewed, neither were darwin's papers.
not sure what you think happens in peer review but it's probably overrated.
The problem right now is that there aren't enough peer reviewers.
I don't think that's the problem.
One problem is that there's no good incentive to spend significant time doing good peer review.
I can see how one of these is the gut feelings origin, and other bodily feelings.
What a way to oversell the discovery.
The reality is:
The headline should have been: "Human forebrain and hindbrain arise from distinct embryonic progenitor lineages" - not that we have "two organs" in the brain.
I mean, I learned a bunch of neat new stuff, so I’m excited!
Though I agree with the detailed differentiation, still for the headline purpose a generic one that resonates with people easily isn't a bad choice
Lying is always a bad choice. The paper in Nature says
"Hence, we postulate the brain is a composite organ emanating from two lineage-restricted progenitors; these dual progenitors may be evolutionarily conserved across 550 million years from hemichordates to mammals."
If they had written instead:
"Human brain was two separate organs"
Then, both attention grabbig and true?
Probably not, because by the time hominids were a thing, it was one.
(if I'm reading parent poster correctly)
Human Brain Evolved From Two Separate Organs.
Are there other composite organs?
Yes, but this is left for the next years because they give only one Nobel preis per year.
https://en.wikipedia.org/wiki/Siphonophore
Given the parallel example cited in the article of jellyfish having two spatially separate organs, & the subsequent speculation that our own ancestors could also have had spacially separate anterior & posterior masses, the title doesn't really seem unreasonable in its hyperbole.
While it might not be perfectly accurate it's hardly misleading.
I found the title confusing, at the very least because it can be argued that the two brain hemispheres are two organs already, as they operate independently when severed from each other.
Additionally the only images in the linked article are also face pics of the researchers instead of anything on the information about said research.
I want to trust science and dislike anti vaxxers but it’s difficult to argue against them when researchers act like the caricature they are mocked as.
Self aggrandizing articles with misleading headlines is giving me 2 triggers for not trusting the content.
It’s the PR arm of a university, they always do this.
Pretty much, and they've less shame than a British tabloid in how far they go.
When submitting, one can try to replace the title with something honest. HN does not favor that, mostly due to submitters having their own biases.
The best tactic is finding a higher quality article on the subject, to submit instead. That's uncertain, takes time, and may run into paywall issues.
Possibly making matters worse, this is from Stanford where they had the university president caught engaging in fraud on Alzheimer’s research.
If the two parts arise independently, then the headline may be a bit clunky but it is technically correct.
I'm pretty sure the third thesis has been taught in my university physiology classes 20 years ago, too.
Oh, I think we could crank that headline even harder while still keeping one toe on the truth. For example:
"Elon Musk's Brain is Two Separate Organs"
Both of Taylor Swift's Brains are Over 500 Million Years Old
People with maternal Jewish DNA have two brains.
I'd have never clicked that headline nor understood why this finding is important.
If you think the original headline is not "truthful" enough, at least do something like "Researchers found the reason why hindbrain cells cannot be grown in a lab and found a way to overcome it"
Depends what the definition of "organ" actually is. What speaks for different organs here is that the cells both have a different pathway from stem cells and have different evolutionary histories. That is different from other brain regions that may have separate functions but still evolved together.
To me, this suddenly turned the discussion into a fascinating exploration and demonstration of different standards of truthfulness in marketing.
I still don't see how the original headline was not truthful.
It's as truthful and useful as "75.6% of humans who ingest oxygen end up dead".
I think it's less about what was said (it is truthful) and more what isn't mentioned in the title which leaves ambiguity.
I don't necessarily think it's intentional. For those with knowledge in the field I suspect it resonates the appropriate reaction.
For those outside of the field, I think the perception of what being 2 organs means does a lot of leg work in invoking a response which seems exaggerated, but is probably caused by incorrect assumptions of what the title is trying to convey.
I hope that makes some sense, I feel that was a lot of word vomit but I'm struggling to find the right words, it's somewhat meta
Why do you think it's important?
I don't have a problem with the 'two organs making one' framing. The fact that they are 'symbiotic' now doesn't change that. In fact it helps me understand two key facts. One can't grow out of the other, and they work differently. Great
Main issue I have with the title is it immediately reminded me about McGilchrist's "The Divided Brain" and I thought they meant the two halves - but that is not the case.
So the question still remains...
https://www.ted.com/talks/iain_mcgilchrist_the_divided_brain
It's cool, but the headline is really pretty misleading.
The new result seems to be that researchers have identified different progenitors for fore/midbrain vs. hindbrain and have found that they can be identified by some specific developmental gene markers. That's genuinely cool.
However, organs are not typically defined by a single tissue characterized by a progenitor that can be labeled with a single gene marker. I suppose it's fine if on a functional and anatomical level you want to split the fore/midbrain and hindbrain into two different "organs", but whether you think of the brain as 1 organ or 2, it really doesn't change much in terms of how you would think about these regions.
It isn't at all surprising that different regions of the brain have localized functions; some of the earliest evidence of this was how focal injuries (like strokes) have characteristic deficit patterns depending on brain region affected, and obviously there has been a lot of work since then further showing the organization, function and development of different brain regions.
The impact is rather that is explains the failure of attempts to cultivate cell cultures of brainstem cells.
A bicameral mind cool
Actually, the mind should only exist in the forebrain:0
And that's why we oftentimes talk about "brains" in the plural
The really exciting thing in this article is that this research led them to a new technique for growing brain stem cells in vitro, which has been very difficult until now. If that isn't being oversold, it's big news. That's going to make future research into diseases like ALS a lot easier.
The title is factually incorrect and is not what the research actually found:
https://www.nature.com/articles/s41593-026-02433-7
Title: "Two parallel neural ectoderm progenitors contribute to the developing brain".
"Hence, we postulate the brain is a composite organ emanating from two lineage-restricted progenitors; these dual progenitors may be evolutionarily conserved across 550 million years from hemichordates to mammals."
I went to see Michael Gazzanigga talk about hemispheric separation some years ago. Fascinating. The two hemispheres can operate separately.
I'm not sure the actual article in Nature Neuroscience [1] actually says that. I remember "Your Brain Is Not an Onion With a Tiny Reptile Inside" [2] from a few years ago, but I'm not sure where the dissonance comes from: my own misunderstanding, the press release using a popular but flawed model to communicate with laymen, or these two articles being in direct contradiction with each other?
[1]: https://www.nature.com/articles/s41593-026-02433-7 [2]: https://journals.sagepub.com/doi/10.1177/0963721420917687
[2] is an annoying pedantic article that illustrates little beyond a misconception of a misconception.
"Your Brain Is Not an Onion With a Tiny Reptile Inside" is a really stupid and pretentious article arguing against a straw man.
Wintermute and neuromancer!
What is the difference between saying that the brain is two organs, as in the title, or a "composite organ" as in the actual paper? What makes an organ a single autonomous organ?
The digestive tract could also be seen as a single organ since they are connected. I think the deciding criteria should be the one applied in this study, i.e., how an organ develops.
Fun fact: 80% of the brain's neurons are in the cerebellum, not the cortex.
In other words: only <20% of pur neuron budget goes to higher cognition (thinking, language, seeing, hearing). 80% is spent on motor skills.
The cerebellum isn't just for motor skills. It's more of a place where very commonly used patterns get a bunch of dedicated wetware so the computation is superfast and precise. In an (undoubtedly very limited) analogy a bunch of FPGAs to complement the general processing. It does make a lot of sense to use this functionality for motor skills, though.
See:
- https://pmc.ncbi.nlm.nih.gov/articles/PMC4089997/
- https://pubmed.ncbi.nlm.nih.gov/38663092/
All the comments I see are about is it two organs, or a composite organ.
Surely the interesting thing is the ability to grow hindbrain cells in vitreo. That's what's potentially going to lead to the cure of lots of things, not whether 1=2.
So, what we colloquially call 'reptile brain' turns out to be somewhat accurate.
Hm, I’m of two minds on this one.
I thought this was widely known, at least for males, where the second one can be found in the lower half of the body.
I don’t think the medical community has believed as the article claims for nearly a century.
Most animal brains have three very different organs in the brain: the cerebrum, cerebellum, and the limbic system (which itself is further divided into numerous differentiated types of tissues)
TFA refers to the evolutionarily history of the brain, not the specialised functionality of different parts of the brain.
that's funny when I was in junior school, 15 years ago, I said in the classroom during science class, that we have 2 brains. everyone including my teacher were laughed at me.