Neurology Question: Why doesn't reduced brain size in dwarfs affect intelligence?

[olds]

I've heard that we only use 10% of our brains.

 

[jhu]

The brain and nervous system wires itself up taking whatever space it can find in the proper regions of the brain. Since average full size adult uses ~10% of brain mass there is still more than enough material in a dwarf's brain.

Why do people keep quoting this 10% bullshit? Based on evolution, we should have 90% less brain mass if this were true since the brain uses about 20% of our caloric intake (vs only being 2% of body mass). That's a really expensive proposition if we were just consuming so many calories for nothing.

 

[olds]

Why do people keep quoting this 10% bullshit? Based on evolution, we should have 90% less brain mass if this were true since the brain uses about 20% of our caloric intake (vs only being 2% of body mass). That's a really expensive proposition if we were just consuming so many calories for nothing.

Why would the part not being used consume calories?
Besides, when out alien forefathers come back they'll teach us to use the rest of our brains. Or eat our brains.

 

[dank69]

Why do people keep quoting this 10% bullshit? Based on evolution, we should have 90% less brain mass if this were true since the brain uses about 20% of our caloric intake (vs only being 2% of body mass). That's a really expensive proposition if we were just consuming so many calories for nothing.

Because 10% of our brain is neurons while the other 90% is glial cells?

 

[jhu]

Because 10% of our brain is neurons while the other 90% is glial cells?

Recent data points closer to 1:1 neurons:glia.

 

[moonbogg]

They are built on a smaller process, like a die shrink.

 

[GodisanAtheist]

Oddly enough the "only use 10% of your brain" theory is probably the most correct one, again probably for the wrong reasons. To the best of our knowledge most of your brain is busy keeping you alive without you having to think about it, and a little bit is directly involved in keeping you sentient. For example your Cerebellum, a full third of your brain's surface area, is dedicated almost solely to smoothing out and coordinating your muscle movements. Without it you'd move like one of those funky robot prosthetics ATOT loves posting videos of: patching one movement into another. The less body mass you have, the less cells your body has, the fewer neurons are required to keep those cells in check.

Also, a pretty good chunk of your brain are the cell axons (that long tail on the end of neurons) while relatively little space is occupied by actual cell bodies. Neurons can just grow shorter to occupy less space since things are closer together without having to really compromise total numbers. On a similar note glia (glue or support cells) are non-neuronal cells that also form a large bulk of brain matter.

The cells don't actually get smaller though, so its not quite like a die shrink...

 

[TheVrolok]

OP is kinda dumb, and this is another example, I think.

Seems to be the most astute post in this thread so far.

 

[Mr. Pedantic]

Because 10% of our brain is neurons while the other 90% is glial cells?

Even if it were 9:1, which is probably isn't, the neurons are completely dependent on glial cells for survival. I don't know how you define "use", but I think "if they weren't there I'd die" is a pretty compelling definition.

 

[dank69]

Even if it were 9:1, which is probably isn't, the neurons are completely dependent on glial cells for survival. I don't know how you define "use", but I think "if they weren't there I'd die" is a pretty compelling definition.

I mean in a way that if a physicist wins the Nobel Prize his 9 assistants don't share the credit.

 

[HamburgerBoy]

Am I the only one that thinks her head looks actually quite large and at least roughly on par with the man standing?

 

[Kadarin]

This bird is more intelligent than your average Fox News viewer: https://www.youtube.com/watch?v=TtmLVP0HvDg

 

[SlitheryDee]

Most dwarfs I've seen have heads that are noticeably over sized for their bodies. That would mean that most of them probably have brains that are close to the normal human size. Perhaps that particular dwarf IS dumber than an average human even though most of the rest of them aren't.

 

[Geosurface]

A couple of things which must be kept in mind (not sure anyone's pointed these out yet) :

1.) Brain size *is* linked to intelligence, but the issue can be more complicated than that also.

2.) Females have smaller brains than males, but this does not have a significant impact on intelligence because of two key factors:

- Female brains pack about the same number of neurons into a smaller space.
- Male brains are larger in part because they have a larger navigation center

(this is why males consistently score much higher on spatial sub-tests of IQ tests, this ties in with who was doing the hunting and tracking in the past - and in some cultures still. Males needed to be able to find their way around better, and to predict the movements of fast-moving prey animals or predator animals in a way female brains did not have to become as refined at doing - this plays into modern observed differences in driving ability, gaming ability, etc BUT REMEMBER THIS IS ALL *ON AVERAGE*)

3.) The larger navigation center is also why whales and dolphins have such large brains. They are intelligent, no doubt, but most of the size advantage they have over human brains is simply in the area dealing with navigation. This is necessary given their life in the ocean and keeping track of migratory patterns, etc.

Interesting side note, you know how they say human brains have actually been shrinking since switching to more agricultural, stable existence? It's this same navigation center which has been the thing shrinking, for obvious reasons.

Even more interesting side note: When explorers first encountered Eskimos they were amazed at their ability to keep their bearings in a vast, featureless arctic environment. No landmarks of any kind were discernible to the European explorers, but the Eskimos knew where they were and how to get back nonetheless.

What I've heard is that Eskimos have the largest brains of any human group, and it is precisely due to an over-sized navigation center in their brains, just like with dolphins and whales.

For this reason I strongly suspect that the old tales of Native Americans (Plains tribes, etc) being fantastic trackers, are probably true and probably tied to this very same reason.

The navigation center in the brain shrinking in Europeans due to switching to a stable, fixed location agricultural society would obviously not have happened to these peoples who never made such a switch.

As others have pointed out, dwarf people usually have a normal sized head. As for the very tiny lady pictured in the OP? I would be very curious to know her IQ. I suspect it may indeed be low.

Phrenology may have been flawed (mostly because of the limits of science of all kinds at that time), but the basic notion that brain size does correlate with intelligence is not wrong. Nor should anyone have ever entertained the idea that it could even possibly be wrong. It's a very common sense connection. It's no coincidence that no other animal has a higher brain size to body size ratio than humans, and that we are also the most intelligent beings on this planet.

But as I said, it is more complicated than just a direct bigger = smarter thing. More considerations than just size have to be taken into account. Which regions of the brain are large? How many neurons are present? etc.

None of this is meant to be racist, sexist, or offensive in any way. I just find this stuff fascinating. I think everyone should find it fascinating. Not let considerations of what's offensive get in the way of that fascination...

I've heard that we only use 10% of our brains.

Not true.

 

[Acanthus]

A couple of things which must be kept in mind (not sure anyone's pointed these out yet) :

1.) Brain size *is* linked to intelligence, but the issue can be more complicated than that also.

2.) Females have smaller brains than males, but this does not have a significant impact on intelligence because of two key factors:

- Female brains pack about the same number of neurons into a smaller space.
- Male brains are larger in part because they have a larger navigation center

(this is why males consistently score much higher on spatial sub-tests of IQ tests, this ties in with who was doing the hunting and tracking in the past - and in some cultures still. Males needed to be able to find their way around better, and to predict the movements of fast-moving prey animals or predator animals in a way female brains did not have to become as refined at doing - this plays into modern observed differences in driving ability, gaming ability, etc BUT REMEMBER THIS IS ALL *ON AVERAGE*)

3.) The larger navigation center is also why whales and dolphins have such large brains. They are intelligent, no doubt, but most of the size advantage they have over human brains is simply in the area dealing with navigation. This is necessary given their life in the ocean and keeping track of migratory patterns, etc.

Interesting side note, you know how they say human brains have actually been shrinking since switching to more agricultural, stable existence? It's this same navigation center which has been the thing shrinking, for obvious reasons.

Even more interesting side note: When explorers first encountered Eskimos they were amazed at their ability to keep their bearings in a vast, featureless arctic environment. No landmarks of any kind were discernible to the European explorers, but the Eskimos knew where they were and how to get back nonetheless.

What I've heard is that Eskimos have the largest brains of any human group, and it is precisely due to an over-sized navigation center in their brains, just like with dolphins and whales.

For this reason I strongly suspect that the old tales of Native Americans (Plains tribes, etc) being fantastic trackers, are probably true and probably tied to this very same reason.

The navigation center in the brain shrinking in Europeans due to switching to a stable, fixed location agricultural society would obviously not have happened to these peoples who never made such a switch.

As others have pointed out, dwarf people usually have a normal sized head. As for the very tiny lady pictured in the OP? I would be very curious to know her IQ. I suspect it may indeed be low.

Phrenology may have been flawed (mostly because of the limits of science of all kinds at that time), but the basic notion that brain size does correlate with intelligence is not wrong. Nor should anyone have ever entertained the idea that it could even possibly be wrong. It's a very common sense connection. It's no coincidence that no other animal has a higher brain size to body size ratio than humans, and that we are also the most intelligent beings on this planet.

But as I said, it is more complicated than just a direct bigger = smarter thing. More considerations than just size have to be taken into account. Which regions of the brain are large? How many neurons are present? etc.

None of this is meant to be racist, sexist, or offensive in any way. I just find this stuff fascinating. I think everyone should find it fascinating. Not let considerations of what's offensive get in the way of that fascination...



Not true.

Tell that to my stupid special male brain. I took an IQ test and did very well on everything EXCEPT for spatial

 

[DCal430]

Am I the only one that thinks her head looks actually quite large and at least roughly on par with the man standing?

Yes you would be, here is another image of her head, compared to her sister, a normal size person.

and another compared to another mans.

obviously her head is much smaller.

 

[DCal430]

Most dwarfs I've seen have heads that are noticeably over sized for their bodies. That would mean that most of them probably have brains that are close to the normal human size. Perhaps that particular dwarf IS dumber than an average human even though most of the rest of them aren't.

I was referring to dwarfs like the one in the OP, with smaller heads. From my understanding they have normal intelligence.

 

[who?]

The quote about humans only using 10% of our brains is from Albert Einstein who was a physicist not a neuroscientist.

 

[Ichinisan]

I was referring to dwarfs like the one in the OP, with smaller heads. From my understanding they have normal intelligence.

That kind of dwarf doesn't seem to be very common. I couldn't make any statements about their intelligence.

Even the more-common kind with larger heads: I don't know of any prominent dwarf scientists or philosophers (but that's probably because dwarves are so rare and they're treated differently).

Peter Dinklage seems REALLY intelligent, but I'm only going by his character in Game of Thrones (one of my favorite characters in all fiction of all media).

 

[BudAshes]

You use a 100% of your brain people. Your brains just suck that's why you are stupid. You are not an underachiever.

 

[tcsenter]

Yeah, I mean, what is the difference between an IQ of ~93 and 116? You'd be hard pressed to tell someone had an IQ slightly less than 100 unless you did some really extensive testing. I think the idea is that, we have some brain cells to spare (in terms of development, not in terms of killing some of them off after adolescence). I'm wondering if brain size starts to become relevant the more intelligent a person is? i.e. no relationship from 85 to 120 but then as you get closer to the supposed 'genius' IQ levels and beyond, it starts to show some relevance?

 

[DCal430]

Yeah, I mean, what is the difference between an IQ of ~93 and 116? You'd be hard pressed to tell someone had an IQ slightly less than 100 unless you did some really extensive testing. I think the idea is that, we have some brain cells to spare (in terms of development, not in terms of killing some of them off after adolescence). I'm wondering if brain size starts to become relevant the more intelligent a person is? i.e. no relationship from 85 to 120 but then as you get closer to the supposed 'genius' IQ levels and beyond, it starts to show some relevance?

Perhaps, it isn't that it doesn't affect their intelligence, but that it doesn't drop it outside of the range of normality. So instead of IQ of 105, they have an IQ of 90. Still in the normal IQ range, but still affected.

 

[noricarter]

One final thing to seriously think about is how you are measuring the size of the brain. Are we considering surface area when making our estimation. Perhaps the lady with the smaller sized head has more surface area because her brain is more striated. Which would make her brain use the space she has more efficiently and 'may' make up the difference in cranial size. Of course I can only speculate and give an alternative solution but an MRI of her brain along with IQ score would certainly help us to narrow down possibilities.

 

[Crono]

One final thing to seriously think about is how you are measuring the size of the brain. Are we considering surface area when making our estimation. Perhaps the lady with the smaller sized head has more surface area because her brain is more striated. Which would make her brain use the space she has more efficiently and 'may' make up the difference in cranial size. Of course I can only speculate and give an alternative solution but an MRI of her brain along with IQ score would certainly help us to narrow down possibilities.

 

[Red Squirrel]

They probably have the same amount of transistors neural nodes, they're just smaller.