There was a book in the 1970s called "The Origin of Consciousness in the Breakdown of the Bicameral Mind" by Julian Jaynes, where he argued that ancient civilizations -- and he used examples from Homer -- lacked the current modern sense of self-consciousness. If you look at their behavior, they interact with some external divine voice that drives their actions, whereas if you read modern literature you see people being driven by an inner voice which they associate with themselves.
This shift from the "bicameral mentality" of the external voice to the modern mentality of the inner voice was hypothesized by Jaynes to be rooted in some biological changes in the brain. At the time there was split brain research that showed these two parts of the brain function independently almost as two different minds in the same skull. See this 2007 survey: https://www.researchgate.net/publication/6323702_The_bicamer...
> they interact with some external divine voice that drives their actions
...in a specific region, in a specific time period, immediately before the economic and then societal crash of the eastern Mediterranean that changed culture in the region forever.
The hypothesis breaks down pretty hard when you realize he just kind of handwaves away people in the rest of the world not having any kind of abrupt cut-over in the styles of recorded literature that forms the backbone of his arguments.
Yes, Jaynes used a comprehensive approach, albeit one rooted in literature. I only threw in "Homer" as an example to be clear that "ancient civilizations" referred to bronze age and before, and that this was not the Joe Rogan kind of ancient civilizations.
Interesting. Might explain why the cerebellum and cortex work so differently? I wonder what the two ancient nervous systems looked like at the point where they merged.
Its a joke. You know they say ADHD types made great hunters thousands of years ago, because they can hyperfocus on that gazelle while constantly keeping their head on a swivel.
For those interested in brain evolution and practical neuroscience/human behavior:
Carl Sagan's books "Broca's Brain" and "The Dragons of Eden" from the 70's-80's are good initial reads on brain composition and evolution. The Sapolsky lectures and books are also great resources.
Clearly.. this is not some new revelation, it has been the default assumption for a very long time, probably over a hundred years.
Damage to the hind brain results in behavioural changes that are blatantly different compared to when the "newer" parts of the brain is damaged. The cerebellum literally even has a different color.
It's a crude analogy, but I would say the hindbrain is more like the system management co-processor or controller that tends to low-level hardware features.
The forebrain is the main processor. It does all the stuff you think of from OS to application, and has some ability to monitor and even interfere in the system management co-processor.
Whether either of these things have interesting internal structure and functional decomposition is left unaddressed. This observation about the progenitor cells is a bit like seeing the BOM that says they come from different suppliers.
I think it's also a bit of guesswork to try to reason out the evolutionary history. I.e. was either unit "in the market" longer and useful on its own, versus essentially complementary parts that just happen to have a divided supply chain! Intuition about evolutionary processes and life makes it really easy to assume the hindbrain is an older, legacy system that existed independently or with other long-lost companion units.
Just for context: parent comment was posted when the submission title was "Human brain is two separate organs, research finds". We've since changed it.
(Perhaps the updated title is less objectionable?)
really? conditional on them actually being neurosurgeon, I'd place a lot more stock on it than on a random headline based on their authority alone. So I, for one, care.
Argument from authority is a bad thing specifically when it's used to make incorrect claims on the basis of authority. But authority as a concept still has plenty of merit.
"You Are Two" [0] is a video that talks about what happens when the connection between the two hemispheres of the brain is severed.
If you've never seen it I HIGHLY recommend it if only to show how weird our brains actually are.
A good chaser to the above is Peter Watts talk on hive minds [1]. He was a neurology research and the author of the famous sci-fi novel Blindgsight [2]
There was a book in the 1970s called "The Origin of Consciousness in the Breakdown of the Bicameral Mind" by Julian Jaynes, where he argued that ancient civilizations -- and he used examples from Homer -- lacked the current modern sense of self-consciousness. If you look at their behavior, they interact with some external divine voice that drives their actions, whereas if you read modern literature you see people being driven by an inner voice which they associate with themselves.
This shift from the "bicameral mentality" of the external voice to the modern mentality of the inner voice was hypothesized by Jaynes to be rooted in some biological changes in the brain. At the time there was split brain research that showed these two parts of the brain function independently almost as two different minds in the same skull. See this 2007 survey: https://www.researchgate.net/publication/6323702_The_bicamer...
It was a successful pop-sci book when it came out, but its conclusions continue to be met with a lot of skepticism today.
Okay but this article is about evolution hundreds of millions of years ago.
This is pretty fuzzy and woo woo
> they interact with some external divine voice that drives their actions
...in a specific region, in a specific time period, immediately before the economic and then societal crash of the eastern Mediterranean that changed culture in the region forever.
The hypothesis breaks down pretty hard when you realize he just kind of handwaves away people in the rest of the world not having any kind of abrupt cut-over in the styles of recorded literature that forms the backbone of his arguments.
Are you sure about this? If you look at the ancient stories in India you can similar phenomena
Yes, Jaynes used a comprehensive approach, albeit one rooted in literature. I only threw in "Homer" as an example to be clear that "ancient civilizations" referred to bronze age and before, and that this was not the Joe Rogan kind of ancient civilizations.
Interesting. Might explain why the cerebellum and cortex work so differently? I wonder what the two ancient nervous systems looked like at the point where they merged.
It might explain ADHD.
Might it? I’m not sure I’m following you. Just because the cerebellum is involved?
Its a joke. You know they say ADHD types made great hunters thousands of years ago, because they can hyperfocus on that gazelle while constantly keeping their head on a swivel.
Seems to be based on the Stanford article: https://med.stanford.edu/news/all-news/2026/09/two-separate-...
For those interested in brain evolution and practical neuroscience/human behavior:
Carl Sagan's books "Broca's Brain" and "The Dragons of Eden" from the 70's-80's are good initial reads on brain composition and evolution. The Sapolsky lectures and books are also great resources.
I'd imagine the science from the 80s is very dated now, no matter how good the book is.
Clearly.. this is not some new revelation, it has been the default assumption for a very long time, probably over a hundred years.
Damage to the hind brain results in behavioural changes that are blatantly different compared to when the "newer" parts of the brain is damaged. The cerebellum literally even has a different color.
Original paper:
https://www.nature.com/articles/s41593-026-02433-7 (paywall)
New Scientist Article:
https://www.newscientist.com/article/2589739-our-brain-evolv...
https://archive.is/1CFX9
Thanks! I've changed the link above to https://www.newscientist.com/article/2589739-our-brain-evolv... from https://medicalxpress.com/news/2026-09-human-brain.html.
So hindbrain is the OS kernel and forebrain the application server ?
It's a crude analogy, but I would say the hindbrain is more like the system management co-processor or controller that tends to low-level hardware features.
The forebrain is the main processor. It does all the stuff you think of from OS to application, and has some ability to monitor and even interfere in the system management co-processor.
Whether either of these things have interesting internal structure and functional decomposition is left unaddressed. This observation about the progenitor cells is a bit like seeing the BOM that says they come from different suppliers.
I think it's also a bit of guesswork to try to reason out the evolutionary history. I.e. was either unit "in the market" longer and useful on its own, versus essentially complementary parts that just happen to have a divided supply chain! Intuition about evolutionary processes and life makes it really easy to assume the hindbrain is an older, legacy system that existed independently or with other long-lost companion units.
That sounds about right.
Maybe more like the baseband modem in a phone?
I think more like file explorer!
Neurosurgeon here: No
Just for context: parent comment was posted when the submission title was "Human brain is two separate organs, research finds". We've since changed it.
(Perhaps the updated title is less objectionable?)
The paper title sits better with me, even as a non-expert: "Two parallel neural ectoderm progenitors contribute to the developing brain".
https://www.nature.com/articles/s41593-026-02433-7
Free preprint:
https://www.biorxiv.org/content/10.1101/2025.07.02.662771v1
Argument from authority. Elaborate or nobody cares.
really? conditional on them actually being neurosurgeon, I'd place a lot more stock on it than on a random headline based on their authority alone. So I, for one, care.
Argument from authority is a bad thing specifically when it's used to make incorrect claims on the basis of authority. But authority as a concept still has plenty of merit.
Correct, but an argument from authority requires certification as an authority.
Otherwise I'm free to claim I'm an authority on your moms butthole.
Authority is a heuristic for which claims are worthy of investigation, not determining their truth
"You Are Two" [0] is a video that talks about what happens when the connection between the two hemispheres of the brain is severed.
If you've never seen it I HIGHLY recommend it if only to show how weird our brains actually are.
A good chaser to the above is Peter Watts talk on hive minds [1]. He was a neurology research and the author of the famous sci-fi novel Blindgsight [2]
0 - https://www.youtube.com/watch?v=wfYbgdo8e-8&vl=en
1 - https://www.youtube.com/watch?v=v4uwaw_5Q3I
2 - https://amzn.to/4xD40td