Our brain evolved from two primitive nervous systems that merged: Study

56 pointsposted 5 hours ago
by Jimmc414

31 Comments

carefree-bob

an hour ago

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...

vor_

7 minutes ago

It was a successful pop-sci book when it came out, but its conclusions continue to be met with a lot of skepticism today.

ProjectArcturis

42 minutes ago

Okay but this article is about evolution hundreds of millions of years ago.

crooked-v

an hour ago

> 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.

ViktorRay

42 minutes ago

Are you sure about this? If you look at the ancient stories in India you can similar phenomena

carefree-bob

39 minutes ago

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.

Chance-Device

17 minutes ago

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.

hbarka

13 minutes ago

It might explain ADHD.

Chance-Device

12 minutes ago

Might it? I’m not sure I’m following you. Just because the cerebellum is involved?

hbarka

5 minutes ago

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.

jschveibinz

5 hours ago

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.

esperent

an hour ago

I'd imagine the science from the 80s is very dated now, no matter how good the book is.

reliablereason

20 minutes ago

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.

srean

5 hours ago

So hindbrain is the OS kernel and forebrain the application server ?

saltcured

3 hours ago

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.

srean

3 hours ago

That sounds about right.

fph

3 hours ago

Maybe more like the baseband modem in a phone?

colinbrain

2 hours ago

Neurosurgeon here: No

dang

an hour ago

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?)

elendilm

44 minutes ago

Argument from authority. Elaborate or nobody cares.

ajkjk

34 minutes ago

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.

pixl97

21 minutes ago

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.

someguynamedq

20 minutes ago

Authority is a heuristic for which claims are worthy of investigation, not determining their truth

alexpotato

37 minutes ago

"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