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

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.

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?

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.

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

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.

What a way to oversell the discovery.

The reality is:

    * 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.

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?

Are there other composite organs?

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.

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.

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

"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.

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".

That’s only wrong because it’s 100%.

Isn't it more like 93%? On the other 7% data is still inconclusive, they never died

I'd have never clicked that headline nor understood why this finding is important.

Why do you think it's important?

You don't 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

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.

A bicameral mind cool

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 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?

[1]: https://www.nature.com/articles/s41593-026-02433-7 [2]: https://journals.sagepub.com/doi/10.1177/0963721420917687

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?

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.

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/

So the 80% is spent on, more generally, habits and intuition. Makes sense.

Hm, I’m of two minds on this one.

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)