Why would an extraversion spectrum evolve?

[rousseau]

Given that the extraversion spectrum exists due to variability in the excitability of a component in the brain (can't recall the name now), I wonder why this should be the case? Is it just that this variability is inevitable with how genetics works? Or does something like the spectrum actually have any evolutionary value?

Additional thoughts: I wonder how balanced the spectrum is between introverts/extroverts.

 

[Peez]

Given that the extraversion spectrum exists due to variability in the excitability of a component in the brain (can't recall the name now), I wonder why this should be the case? Is it just that this variability is inevitable with how genetics works? Or does something like the spectrum actually have any evolutionary value?

Additional thoughts: I wonder how balanced the spectrum is between introverts/extroverts.

I cannot comment on the physiology or genetics of this trait, but you might find frequency dependent selection relevant.

Peez

 

[rousseau]

Given that the extraversion spectrum exists due to variability in the excitability of a component in the brain (can't recall the name now), I wonder why this should be the case? Is it just that this variability is inevitable with how genetics works? Or does something like the spectrum actually have any evolutionary value?

Additional thoughts: I wonder how balanced the spectrum is between introverts/extroverts.

I cannot comment on the physiology or genetics of this trait, but you might find frequency dependent selection relevant.

Peez

Yea that's kind of a part of the premise of the question. Assuming the spectrum exists due to sexual selection, the question is why it's existence is advantageous. But even then, I'm not convinced it exists due to sexual selection and isn't just the product of random variability like eye or hair colour.

 

[steve_bank]

Nature vs nurture. The steriotypical English is reserved, cemtral and South American and other cultures are open and overtly social, gregarious.. Same with what I have seen with immigrant West African cuktures.

 

[rousseau]

Nature vs nurture. The steriotypical English is reserved, cemtral and South American and other cultures are open and overtly social, gregarious.. Same with what I have seen with immigrant West African cuktures.

This misses the crux of the question too. It's why should there be a spectrum at all. Presumably every feature of human anatomy has an evolutionary purpose, so why should there be a delineation between introverts/extroverts, and not just a ubiquitous, static point on the spectrum for everyone?

 

[steve_bank]

Nature vs nurture. The steriotypical English is reserved, cemtral and South American and other cultures are open and overtly social, gregarious.. Same with what I have seen with immigrant West African cuktures.

This misses the crux of the question too. It's why should there be a spectrum at all. Presumably every feature of human anatomy has an evolutionary purpose, so why should there be a delineation between introverts/extroverts, and not just a ubiquitous, static point on the spectrum for everyone?

Someday in the distant future science will likely have a working model of the brain down to neurons.

That still would not answer your question.

The universal question 'why?' is not answerable. Why does the universe exist and what is the purpose of the universe? To me somewhat unanswerable questions. People adopt religion and philosophies that satisfy them, that is what religion and philosophy are for.

Scientifically the answer is a combination of generics and environment. I believe families statistically can be prone to insanity, is it genetics or family culture.

Not all behavior can be reduced to evolutionary advantage.

As to a spectrum of behavior, if everybody turned out to be Type A aggressives we'd be in trouble socially. Society is structured naturally into leaders and followers. IMO part geneti

Height and vocal quality have distributions, is there any advantage to that?.

 

[Peez]

Given that the extraversion spectrum exists due to variability in the excitability of a component in the brain (can't recall the name now), I wonder why this should be the case? Is it just that this variability is inevitable with how genetics works? Or does something like the spectrum actually have any evolutionary value?

Additional thoughts: I wonder how balanced the spectrum is between introverts/extroverts.

I cannot comment on the physiology or genetics of this trait, but you might find frequency dependent selection relevant.

Peez

Yea that's kind of a part of the premise of the question. Assuming the spectrum exists due to sexual selection, the question is why it's existence is advantageous. But even then, I'm not convinced it exists due to sexual selection and isn't just the product of random variability like eye or hair colour.

Keeping in mind that I have not seen any genetic component to this behaviour demonstrated, and that this is pure speculation...

If being an introvert makes you better (than extroverts) at certain tasks, and being an extrovert makes you better (than introverts) at other tasks, then selection might act on this range of traits. If the advantage/disadvantage associated with being an extrovert or introvert depends on how common introverts are in the group, then frequency-dependent selection may occur. This might be through sexual selection or any other component of selection. For example, if being an introvert is an advatnage when introverts are rare but a disadvantage when introverts are common, we would expect selection to tend to maintain a population with some introverts and some extroverts.

Obviously this is simplistic, but hopefully it is clear.

Peez

 

[Peez]

Nature vs nurture. The steriotypical English is reserved, cemtral and South American and other cultures are open and overtly social, gregarious.. Same with what I have seen with immigrant West African cuktures.

This misses the crux of the question too. It's why should there be a spectrum at all. Presumably every feature of human anatomy has an evolutionary purpose, so why should there be a delineation between introverts/extroverts, and not just a ubiquitous, static point on the spectrum for everyone?

I don't think that my response missed the crux of the question, though perhaps I did not explain myself clearly. In any event it would be very dangerous to assume that "every feature of human anatomy has an evolutionary purpose" (evolutionary biologists do not make this assumption).

I should add that it is quite possible that variation in 'vertedness' might not be due to selection, as you suggest it might be due to limitations of genetics and development combined with environmental variation.

Peez

 

[rousseau]

Nature vs nurture. The steriotypical English is reserved, cemtral and South American and other cultures are open and overtly social, gregarious.. Same with what I have seen with immigrant West African cuktures.

This misses the crux of the question too. It's why should there be a spectrum at all. Presumably every feature of human anatomy has an evolutionary purpose, so why should there be a delineation between introverts/extroverts, and not just a ubiquitous, static point on the spectrum for everyone?

I don't think that my response missed the crux of the question, though perhaps I did not explain myself clearly. In any event it would be very dangerous to assume that "every feature of human anatomy has an evolutionary purpose" (evolutionary biologists do not make this assumption).

I should add that it is quite possible that variation in 'vertedness' might not be due to selection, as you suggest it might be due to limitations of genetics and development combined with environmental variation.

Peez

I think that might be the crux of it, but I wonder if it's true. Just a result of the nature of genetics with results that are arbitrary to survival value a majority of the time. Similar to things like height, foot-size, eye-colour, etc.

 

[Peez]

I don't think that my response missed the crux of the question, though perhaps I did not explain myself clearly. In any event it would be very dangerous to assume that "every feature of human anatomy has an evolutionary purpose" (evolutionary biologists do not make this assumption).

I should add that it is quite possible that variation in 'vertedness' might not be due to selection, as you suggest it might be due to limitations of genetics and development combined with environmental variation.

Peez

I think that might be the crux of it, but I wonder if it's true. Just a result of the nature of genetics with results that are arbitrary to survival value a majority of the time. Similar to things like height, foot-size, eye-colour, etc.

It is certainly possible, or it might be frequency-dependent selection, or maybe even group selection (though that would be a stretch), at this point it is all speculation.

Peez

 

[Kharakov]

Given that the extraversion spectrum exists due to variability in the excitability of a component in the brain (can't recall the name now), I wonder why this should be the case? Is it just that this variability is inevitable with how genetics works? Or does something like the spectrum actually have any evolutionary value?

Additional thoughts: I wonder how balanced the spectrum is between introverts/extroverts.

Check the balance between:

predator social extrovert
predator social introvert
predator non-social extrovert
predator non-social introvert

prey social extrovert
prey social introvert
prey non-social extrovert
prey non-social introvert


in nature. You might find a pattern.

 

[steve_bank]

rousseau, did you get a needed catharsis?

 

[rousseau]

Nature vs nurture. The steriotypical English is reserved, cemtral and South American and other cultures are open and overtly social, gregarious.. Same with what I have seen with immigrant West African cuktures.

This misses the crux of the question too. It's why should there be a spectrum at all. Presumably every feature of human anatomy has an evolutionary purpose, so why should there be a delineation between introverts/extroverts, and not just a ubiquitous, static point on the spectrum for everyone?

I don't think that my response missed the crux of the question, though perhaps I did not explain myself clearly. In any event it would be very dangerous to assume that "every feature of human anatomy has an evolutionary purpose" (evolutionary biologists do not make this assumption).Peez

I only make that comment because sexual selection was a given and assumed in the question. Where the question was more along the lines of 'why should sexual selection produce a spectrum', in the same way one would ask 'why would sexual selection produce eyes'. To have eyes has very clear value to survival and so it's selection is intuitive, so what is the survival value conferred by the coming into existence of an extraversion spectrum.

But on second thought, I think your answer here:

If being an introvert makes you better (than extroverts) at certain tasks, and being an extrovert makes you better (than introverts) at other tasks, then selection might act on this range of traits.

Hits at the heart of it. Personalities diverge where social specialization is more varied and contains more niches to be exploited. And so it's possibly not so much that there is a 'spectrum' per se, just a wider range of personality traits being selected for, for different reasons, which makes human personality very dynamic.

 

[Peez]

I don't think that my response missed the crux of the question, though perhaps I did not explain myself clearly. In any event it would be very dangerous to assume that "every feature of human anatomy has an evolutionary purpose" (evolutionary biologists do not make this assumption).Peez

I only make that comment because sexual selection was a given and assumed in the question. Where the question was more along the lines of 'why should sexual selection produce a spectrum', in the same way one would ask 'why would sexual selection produce eyes'. To have eyes has very clear value to survival and so it's selection is intuitive, so what is the survival value conferred by the coming into existence of an extraversion spectrum.

Are you perhaps confusing sexual selection and frequency-dependent selection?

Peez

 

[rousseau]

I don't think that my response missed the crux of the question, though perhaps I did not explain myself clearly. In any event it would be very dangerous to assume that "every feature of human anatomy has an evolutionary purpose" (evolutionary biologists do not make this assumption).Peez

I only make that comment because sexual selection was a given and assumed in the question. Where the question was more along the lines of 'why should sexual selection produce a spectrum', in the same way one would ask 'why would sexual selection produce eyes'. To have eyes has very clear value to survival and so it's selection is intuitive, so what is the survival value conferred by the coming into existence of an extraversion spectrum.

Are you perhaps confusing sexual selection and frequency-dependent selection?

Peez

No, not really.. just using the terms interchangeably.

 

[Peez]

Are you perhaps confusing sexual selection and frequency-dependent selection?

Peez

No, not really.. just using the terms interchangeably.

Um, since sexual selection and frequency-dependent selection are entirely different things, if you are using the terms interchangeably then you are confusing these two processes.

Peez

 

[lpetrich]

Given that the extraversion spectrum exists due to variability in the excitability of a component in the brain (can't recall the name now), I wonder why this should be the case? Is it just that this variability is inevitable with how genetics works? Or does something like the spectrum actually have any evolutionary value?

Those are questions that can be asked of biological variability in general. There are several possible reasons that I can think of:

• Imprecision in development and growth
• Environmental effects
• Genetic variation
  • Variation that is not selected against, like size incompatibility
  • Selection for exploiting a range of niches
  • Selection for variety to decrease vulnerability to disease organisms

 

[steve_bank]

My sister said my nephew had grown introverted. What brought him out of it was participation in karate.

Behavior modification works, maybe not always. You can pay for fear of flying treatments. You are gradually led up to flights.

Some people are terrified of heights or leaving their home.

 

[rousseau]

Are you perhaps confusing sexual selection and frequency-dependent selection?

Peez

No, not really.. just using the terms interchangeably.

Um, since sexual selection and frequency-dependent selection are entirely different things, if you are using the terms interchangeably then you are confusing these two processes.

Peez

Yea that's correct, I'm just using sexual selection as a catch all term to describe the processes that lead to phenotypic selection.. kind of a short-hand. The question assumes that this part of our personality was selected for, but the question was why it was selected for.

 

[Peez]

Um, since sexual selection and frequency-dependent selection are entirely different things, if you are using the terms interchangeably then you are confusing these two processes.

Peez

Yea that's correct, I'm just using sexual selection as a catch all term to describe the processes that lead to phenotypic selection.. kind of a short-hand. The question assumes that this part of our personality was selected for, but the question was why it was selected for.

Simply "selection" works well to cover all sorts (sexual selection, fecundity selection, survival selection, etc., or directional, balancing, disruptive, or frequency-dependent, frequency-independent...). You do pose a potentially interesting question, but if selection is responsible for maintaining variation in a trait then typical directional selection (sexual or other) is not expected to do so. However, frequency-dependent selection could maintain exactly that sort of variation.

Peez