The Triune system

[Sriram]

Hi everyone,

The Triune system is one of the most famous and well accepted ways of classifying the brain and its evolutionary development.

The human brain is said to consist of three systems... The Reptilian system, the Limbic system and the Neo Cortex.

The Reptilian system is responsible for aggression, dominance, territorial behavior. The Limbic system is said to be responsible for emotion, reproductive  and parental behavior. The Neo Cortex is said to be responsible for language, planning abstract thinking and so on.

In evolutionary terms the first one is said to have evolved in reptiles and the second in early mammals and the Neo Cortex in higher mammals and more so in humans.

Of course, this division is not accepted today in such a clear cut manner as in earlier decades, because many organisms have been found to be exceptions to these stages of development. Also, in humans, all the three systems function in an integrated manner as one unit.

Regardless of this, the Triune system is still regarded as one of the most representative models in relation to brain development and functioning.

IMO...the Triune system shows that advanced brain development in higher mammals did not happen merely as an extension of the earlier ones but appears to have developed as separate systems with separate structures.....with a step up at each level.

Just some thoughts.

Cheers.

Sriram

[jeremyp]

IMO...the Triune system shows that advanced brain development in higher mammals did not happen merely as an extension of the earlier ones but appears to have developed as separate systems with separate structures.....with a step up at each level.

The triune brain was proposed in the 1960's. Research has moved on since then and it's no longer regarded as a particularly accurate model.

https://en.wikipedia.org/wiki/Triune_brain#Status_of_the_model

[Sriram]

The triune brain was proposed in the 1960's. Research has moved on since then and it's no longer regarded as a particularly accurate model.

https://en.wikipedia.org/wiki/Triune_brain#Status_of_the_model

Yes...I agree....but from the same site....

"It continues to hold public interest because of its simplicity. While technically inaccurate as an explanation for brain activity, it remains one of very few approximations of the truth we have to work with: the "neocortex" represents that cluster of brain structures involved in advanced cognition, including planning, modeling and simulation; the "limbic brain" refers to those brain structures, wherever located, associated with social and nurturing behaviors, mutual reciprocity, and other behaviors and affects that arose during the age of the mammals; and the "reptilian brain" refers to those brain structures related to territoriality, ritual behavior and other "reptile" behaviors."

[Shaker]

Yes...I agree....but from the same site....

"It continues to hold public interest because of its simplicity. While technically inaccurate as an explanation for brain activity ..."

And that's the point where you should have stopped.

If you're bothered in any way about accuracy, at any rate.

[torridon]

I seem to remember reading that an octopus has nine brains.  Must be awfully confusing for the poor thing.  I wonder if it has free wills ....

[Walt Zingmatilder]

I seem to remember reading that an octopus has nine brains.  Must be awfully confusing for the poor thing.  I wonder if it has free wills ....

Octopus should read ''antitheism'' and nine should read ''nein''.

[torridon]

IMO...the Triune system shows that advanced brain development in higher mammals did not happen merely as an extension of the earlier ones but appears to have developed as separate systems with separate structures.....with a step up at each level.

Entirely novel selection pressures at particular points in time would likely have elicited corresponding novel cortical structures, added like a new dollop of ice cream to what was there before.  The brain is good at that, we have even seen how new cortex can be conscripted/grown in taxi drivers during the course of an individual's working life.

[Sriram]

Entirely novel selection pressures at particular points in time would likely have elicited corresponding novel cortical structures, added like a new dollop of ice cream to what was there before.  The brain is good at that, we have even seen how new cortex can be conscripted/grown in taxi drivers during the course of an individual's working life.

You give lot of credit to the brain.   As though it knew what was required of it and created itself.

The usual 'explanation' of millions of random variations and NS....I suppose. 

The brain is pliable...of course.  But that only shows that the brain isn't responsible for its own creation and modifications. There are other mechanisms that are responsible for it.....besides some sort of a communication with the environment. Epigenetics must play a part somewhere!

Personally, I believe that evolution is directed and that all these modifications and structural changes (like all other emergent properties) are clearly 'hardware' modifications meant to accommodate  higher mental functions. 

[jeremyp]

Personally, I believe that evolution is directed and that all these modifications and structural changes (like all other emergent properties) are clearly 'hardware' modifications meant to accommodate  higher mental functions.

Evolution isn't directed, so you are wrong.

[Shaker]

Personally, I believe that evolution is directed

Why?

[torridon]

Personally, I believe that evolution is directed and that all these modifications and structural changes (like all other emergent properties) are clearly 'hardware' modifications meant to accommodate  higher mental functions.

What's your justification for that ?

[Bubbles]

It's directed by events.

Some things do direct it, change mainly.

IMO.

[torridon]

I don't think that is what people mean by 'directed'.  In the context of evolution, at least, 'directed', implies intentionality, some unseen intelligent guiding hand, not just random events.

[Sriram]

From bacteria to humans is definitely'directed' evolution for me.  It cannot be entirely due to random variation. There are several species in bacteria itself to account for random variation and survival instinct...if those are the only basis for change.

All the emergent properties required to account for increasing complexity would run into millions or billions.  Every emergent property that leads from bacteria to humans is a step up in the right 'direction'.

Read together with the Anthropic Principle.....humans simply had to happen.   The Triune system is only one such example.

[Shaker]

 

[Stranger]

From bacteria to humans is definitely'directed' evolution for me.  It cannot be entirely due to random variation. There are several species in bacteria itself to account for random variation and survival instinct...if those are the only basis for change.

All the emergent properties required to account for increasing complexity would run into millions or billions.  Every emergent property that leads from bacteria to humans is a step up in the right 'direction'.

Read together with the Anthropic Principle.....humans simply had to happen.   The Triune system is only one such example.

Clearly just as clueless about evolution as you are about physics...

[Shaker]

Yup.

[Sriram]

Thanks for keeping your views short...both of you. Much obliged! 

[Shaker]

Thanks for keeping your views short...both of you. Much obliged! 

An example for you to emulate, perchance.

[Stranger]

Thanks for keeping your views short...both of you. Much obliged! 

Sorry, but the problem is that you clearly haven't looked into the basics.

From bacteria to humans is definitely'directed' evolution for me.

It either is or it isn't - it can't be just for you.

Probably, strictly speaking, humans didn't evolve from bacteria anyway.
http://evolution.berkeley.edu/evolibrary/article/0_0_0/evo_04

It cannot be entirely due to random variation.

Nobody who knows about the subject would claim was. It's random variation with natural selection.

There are several species in bacteria itself to account for random variation and survival instinct...if those are the only basis for change.

Natural selection isn't "survival instinct". You give no basis for the assertion that there are enough species of bacteria to account for undirected evolution. How would you even begin to make such a calculation?

After that it's down hill all the way. Seems nothing more than faith and personal incredulity.

[Sriram]

Oh God...now you've gone and elaborated!

Natural selection is not survival instinct....but it is driven by the survival instinct. Otherwise there is no reason why anything should at all survive in a changing environment. Just die out and ....finish! Why should life continue at all? That itself is a clear objective and shows a direction & goal.

[Shaker]

Natural selection is not survival instinct....but it is driven by the survival instinct.

No it isn't.

Seriously, get a clue.

Otherwise there is no reason why anything should at all survive in a changing environment. Just die out and ....finish! Why should life continue at all? That itself is a clear objective and shows a direction & goal.

No it doesn't. You're embarrassing yourself.

[Gordon]

 Otherwise there is no reason why anything should at all survive in a changing environment. Just die out and ....finish! Why should life continue at all? That itself is a clear objective and shows a direction & goal.

That is what you'd like to be the case: but it isn't the case.

[Stranger]

Otherwise there is no reason why anything should at all survive in a changing environment. Just die out and ....finish! Why should life continue at all? That itself is a clear objective and shows a direction & goal.

It doesn't, it really, really doesn't.

I give up - start here:-
http://evolution.berkeley.edu/evolibrary/article/evo_01

[Sriram]

Why is the survival instinct being denied here?!! LOL!  Cynicism is becoming a habit guys. Not healthy.