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.

> 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

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 actual research says something far less clickworthy. Are Stanford's PR dribbles now created by LLMs ?

"Two parallel neural ectoderm progenitors contribute to the developing brain

Abstract When and how different brain regions diversify from one another remains unresolved.

Does a common neural ectoderm progenitor generate the entire brain? Or do multiple neural ectoderm progenitors exist, each restricted to form specific brain regions?

Here our lineage tracing studies of mouse embryos support the latter model. Two parallel brain progenitors emerge simultaneously during gastrulation: anterior neural ectoderm (forebrain/midbrain progenitor) and posterior neural ectoderm (hindbrain progenitor). Differentiation of human pluripotent stem cells into anterior or posterior neural ectoderm-like cells revealed these were lineage committed to forebrain/midbrain versus hindbrain fates, respectively. They harbored diverging chromatin landscapes foreshadowing future forebrain/midbrain versus hindbrain identities. We further differentiated human pluripotent stem cells into hindbrain rhombomere 5/6-specific motor neurons, which were hitherto difficult to generate in vitro.

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."

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.

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.

> 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

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.

Related https://www.newscientist.com/article/2589739-our-brain-evolv... https://news.ycombinator.com/item?id=49755533

Hm, I’m of two minds on this one.

Stanford researcher discovers his head and his ass aren't the same thing.

That headline's as psyoppy as "schizophrenia".

I learned of the Triune Brain through Carl Sagan's book The Dragons of Eden. It was an engaging, story-telling approach to a somewhat, in hindsight controversial concept. It sounds (oversimplified) like the paper the article describes here is an embryological validation of this model.

I honestly can't wait for AI to analyze the brain so we can truly understand the composition of it.

I always come back to this man and it ... no pun intended.. really blows my mind.

https://www.cbc.ca/radio/asithappens/as-it-happens-thursday-...

Terrible headline, cool research.

The brain is a composit of cells from two lineages that separate very early in development and reflect a deeper spatial and functional separation deep in the history of metazoan (read: animal) evolution.

Tying all this to humans specifically is just confusing. This is something that’s seen in a substantial portion of animals, and as such has nothing to do with “ poetry, mathematics and wondering about our own origins”. These features of humans evolved hundreds of millions of years after this two lineage composite organization of animal brains evolved.

I wish the article hadn’t gone out of its way in confusing these issues to push the “relevance” of the research. It’s a pretty remarkable finding anyway.

Tabloid like headline...

Pity about the dumbed down for dummies, fake marketing from Stanford.

So, what we colloquially call 'reptile brain' turns out to be somewhat accurate.

Which is the one zombies hunger for and which is the one driving their unstoppable hunger? Maybe they just really miss having their brain whole again, and eating and walking is the only thing they know?

Does each separate “organ” here have any relationship to the two separate functions identified in “Thinking, Fast and Slow”?

There's a very interesting split-brain experiment [1] and Joe Scott's video about it [2]

TL;DW: Doctors treated corpus callosotomy by severing the bundle of nerve fibers that connect hemispheres of the brain. The surgery effectively stopped seizures from spreading. Left hemisphere handles language, speech, and logical interpretation, right hemisphere handles visual, spatial, and literal tasks.

Because human eyes send visual information to opposite sides of the brain, researchers could show images only to the non-speaking right brain. The right brain could see and physically react to the image (like picking up a matching object with the left hand), but the patient couldn't verbally explain what they were seeing because the left brain was literally in the dark. Instead of saying "I don't know," the speaking left brain would instantly and confidently invent a logical—but completely fake—justification for the action.

[1]: https://en.wikipedia.org/wiki/Split-brain [2]: https://www.youtube.com/watch?v=_TYuTid9a6k

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)

I feel like, even though they got this knowledge, any researcher at any time could have grown hindbrain cells from pluripotent stem cells -- the resulting practice didn't _require_ the understanding. I also don't get why they needed a pluripotent stem cell and not, say, another hindbrain neuron. I get the claim that you can't get forebrain neurons to act like hindbrain neurons, but is it possible that every previous researcher who was trying to grow hindbrain neurons in vitro was starting with forebrain neurons?

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?

I can see how one of these is the gut feelings origin, and other bodily feelings.

Isn’t it funny how Freud, and probably earlier thinkers, have suggested exactly that the mind is layered like this.

I thought this was widely known, at least for males, where the second one can be found in the lower half of the body.

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We are going to have to deprecate an idiom or two. "I'm in two minds about something" now gives the wrong meaning.

[dupe] https://news.ycombinator.com/item?id=49755533

Not just humans… all mammals.

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.

I expected an article full of basic medical jargon: cerebrum, cerebellum, cortex, synapse, etc. Instead it's talking about "forebrain" and "hindbrain". This sounds remarkably unscientific.

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."

A bicameral mind cool

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.

I wasn't expecting to get hit by AI generated slop on Standford's website. At least mark the article as being produced by AI.

> “What they found was striking: … These differences essentially locked each progenitor cell into its respective fate, like travelers on parallel tracks that never cross.”

The dramatic colon, the obligatory closing metaphor, makes me ill.

I went to see Michael Gazzanigga talk about hemispheric separation some years ago. Fascinating. The two hemispheres can operate separately.

How occurate its any experts ?

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Wintermute and neuromancer!

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.

And that's why we oftentimes talk about "brains" in the plural

I worked with a doctor once to build a 3D Model of the brain apertures.

Disclaimer: the work presents these as spiritual/meditational reference points, not established neuroanatomical structures.

Textual reconstruction of the “Brain Apertures” diagram used in the Radhasoami/Surat Shabd Yoga tradition. The named “apertures” are spiritual/meditational reference points in this tradition; labels such as temporal lobe, occipital lobe, cerebellum and brain stem are anatomical landmarks shown in the source diagram in the doc below.

Some details here: https://docs.google.com/document/d/1N9KxIWNF_z9twZurRgkTLljf...