Brain Gene

[rocketman]

This is very interesting. A gene that makes us smarter than chimps has possibly been discovered. No surprises there, but the nature of the find is just as interesting. I have no doubt that comments like the folllowing are going to be seen as exciting for mainstream scientists but will also no doubt bring a smile to the face of creationists.

"There are only two differences in that one gene between a chimp and a chicken, Haussler said. But there are 18 differences in that one gene between human and chimp and they all seemed to occur in the development of man, he said."

"However, the gene changed so fast that Clark said that he has a hard time believing it unless something unusual happened in a mutation. It's not part of normal evolution, he said."

Just thought both sides would be interested in this one.

 

[Quiddity]

"a very dramatic change in a relatively short period of time."

I will certainly keep an eye on this one. Very interesting.

 

[fantome profane]

Encephalization in hominids has long been understood as one of the fastest evolutionary changes that we know of. And of course it is also well known that brain size is one of the main ways in which humans differ from chimps. So in that respect this story is nothing new. Obviously a rapid change in brain size would have been caused by a rapid change in the genetic structure. What is new here is the isolation of one of the key genes that may have been responsible, and that is definitely fascinating. But this is in no way a threat to evolution. We are simply gaining greater understanding of what the fossil record has already shown us.

Also please keep in mind that when we use phrases like “rapid change” and “relatively short period of time” we are still talking about millions of years.

 

[Quiddity]

Encephalization in hominids has long been understood as one of the fastest evolutionary changes that we know of. And of course it is also well known that brain size is one of the main ways in which humans differ from chimps. So in that respect this story is nothing new. Obviously a rapid change in brain size would have been caused by a rapid change in the genetic structure. What is new here is the isolation of one of the key genes that may have been responsible, and that is definitely fascinating. But this is in no way a threat to evolution. We are simply gaining greater understanding of what the fossil record has already shown us.

Also please keep in mind that when we use phrases like “rapid change” and “relatively short period of time” we are still talking about millions of years.

So this isn't necessarily have to do with size (of the brain) per se. But rather mass, correct?

 

[fantome profane]

So this isn't necessarily have to do with size (of the brain) per se. But rather mass, correct?

I am not sure what you are getting at here. The brain definitely increased in size through human evolution and of course along with a corresponding increase in the mass of the brain. I think that when people talk about brain density they are referring to the number of neurons per cubic centimeter. I don’t know if that means that the brain is actually more dense in the sense of mass/volume.

You might be referring to the fact that the size of the brain must be considered in relation to the overall size of the animal. This produces something called the Encephalization Quotient (EQ). Elephants and other large animals have brains much larger than humans, but when you consider them in relation to body size their EQ is much lower.


(sorry if none of this has anything to do with what you were refering to)

 

[Quiddity]

I am not sure what you are getting at here. The brain definitely increased in size through human evolution and of course along with a corresponding increase in the mass of the brain. I think that when people talk about brain density they are referring to the number of neurons per cubic centimeter. I don’t know if that means that the brain is actually more dense in the sense of mass/volume.

You might be referring to the fact that the size of the brain must be considered in relation to the overall size of the animal. This produces something called the Encephalization Quotient (EQ). Elephants and other large animals have brains much larger than humans, but when you consider them in relation to body size their EQ is much lower.


(sorry if none of this has anything to do with what you were refering to)

What I was getting to is that the brain size doesn't necessarily mean you are smarter. One can have a larger brain but very low density (mass/volume). Or does one have to come with the other?

 

[michel]

Very interesting. Thanks for sharing; now at least I know which of my genes is faulty.....

 

[Quiddity]

Very interesting. Thanks for sharing; now at least I know which of my genes is faulty.....

That makes two of us...

 

[fantome profane]

What I was getting to is that the brain size doesn't necessarily mean you are smarter. One can have a larger brain but very low density (mass/volume). Or does one have to come with the other?

Right, absolutely. That is kind of what I was getting at with the EQ thing in reference to brain size of different species. But even in comparing humans a larger brain does not necessarily indicated greater intelligence. I don’t want to start a gender war here but on average men have larger brains than women. That clearly does not mean that men are smarter. And even among humans of the same gender, a 6’5” 300 lb football player might have a larger brain than a 5’5” 120 lb nuclear physicist, but that does not mean the football player is smarter (I don’t mean to disparage the intelligence of football players here either, but you get my point).

And this may be due to brain density. But that is kind of where you are throwing me off when you talk about mass. Brain density has more to do with the number of neurons and how they are structured then it does the actual mass. It is a different use of the word “density”. As I mentioned it refers to neurons per cubic centimeter, rather than just mass per volume.

So it is quite conceivable for someone with a very dense neurological structure to be more intelligent than someone with a larger brain. But there are limits to this. It is easy to imagine someone with a 1200 cc brain size being as intelligent (or more intelligent) than someone with a 1400 cc brain size. But it is harder to imagine someone with a 300 cc brain size (a chimp) being in the same league as either of them.

But getting back to the original point of this thread, although it is not possible to consider neurological structure when dealing with species that have been extinct for hundreds of thousands of years, we can take body mass into account. Human evolution from the australopithecines, to the early hominids to modern humans generally shows an increase in body size, but the brain increased in a way that was way out of proportion. And again to compare modern humans and modern chimps, humans are generally larger in body size. An adult male chimp may be about 4’ tall and around 130 lbs, but I know adult male humans who are smaller than that. (Most people picture chimps much smaller than this because often when they are seen in the movies or on TV they use an infant or adolescent chimp, they are cuter and easier to manage). The point is that the difference in body size is slight compared to the extreme difference in brain size, as well as complexity.

So although you cannot make an absolute correlation between brain size and intelligence, when dealing with humans and chimps, or humans and a common ancestor we may have shared with chimps, we can certainly say that a greater intelligence resulted from the larger brain size.

 

[Quiddity]

Right, absolutely. That is kind of what I was getting at with the EQ thing in reference to brain size of different species. But even in comparing humans a larger brain does not necessarily indicated greater intelligence. I don’t want to start a gender war here but on average men have larger brains than women. That clearly does not mean that men are smarter. And even among humans of the same gender, a 6’5” 300 lb football player might have a larger brain than a 5’5” 120 lb nuclear physicist, but that does not mean the football player is smarter (I don’t mean to disparage the intelligence of football players here either, but you get my point).

And this may be due to brain density. But that is kind of where you are throwing me off when you talk about mass. Brain density has more to do with the number of neurons and how they are structured then it does the actual mass. It is a different use of the word “density”. As I mentioned it refers to neurons per cubic centimeter, rather than just mass per volume.

So it is quite conceivable for someone with a very dense neurological structure to be more intelligent than someone with a larger brain. But there are limits to this. It is easy to imagine someone with a 1200 cc brain size being as intelligent (or more intelligent) than someone with a 1400 cc brain size. But it is harder to imagine someone with a 300 cc brain size (a chimp) being in the same league as either of them.

But getting back to the original point of this thread, although it is not possible to consider neurological structure when dealing with species that have been extinct for hundreds of thousands of years, we can take body mass into account. Human evolution from the australopithecines, to the early hominids to modern humans generally shows an increase in body size, but the brain increased in a way that was way out of proportion. And again to compare modern humans and modern chimps, humans are generally larger in body size. An adult male chimp may be about 4’ tall and around 130 lbs, but I know adult male humans who are smaller than that. (Most people picture chimps much smaller than this because often when they are seen in the movies or on TV they use an infant or adolescent chimp, they are cuter and easier to manage). The point is that the difference in body size is slight compared to the extreme difference in brain size, as well as complexity.

So although you cannot make an absolute correlation between brain size and intelligence, when dealing with humans and chimps, or humans and a common ancestor we may have shared with chimps, we can certainly say that a greater intelligence resulted from the larger brain size.

Well doesn't more dense = more mass?

 

[sparc872]

Well doesn't more dense = more mass?

It seems that would depend entirely on what is in between the neurons. if a neuron had long axons and dendrites, then the mass could equal a brain with lots of neurons and shorter axons and dendrites.

 

[Quiddity]

It seems that would depend entirely on what is in between the neurons. if a neuron had long axons and dendrites, then the mass could equal a brain with lots of neurons and shorter axons and dendrites.

If they are longer then wouldn't you need more space for that?

 

[fantome profane]

Well doesn't more dense = more mass?

No, that is what I am trying to say. If you look up the word density it will say mass per volume. But if you look up the term “brain density” it will say neurons per volume. It is a slightly different use of the word.

Does one cubic centimetre of human brain weight more than one cubic centimetre of chimp brain? Actually I don’t know. And that just got added to my list of things to look up (damm you Victor - j/k). But I don’t think it actually needs to weigh more in order to have a more “dense” neurological structure. But even at this generally what we are looking at when talking about the evolution of the human brain is the increase in size.


Btw, we are so use to looking at the human head that it seems perfectly normal to us, but if you really compare it to other mammals, it is quite bulbous. We are walking around with a balloon on our heads.

 

[rocketman]

What is new here is the isolation of one of the key genes that may have been responsible, and that is definitely fascinating. But this is in no way a threat to evolution.

That's right.

It's not that it's an argument against evolution, but it does add to the standard creationist model. The Genesis account has man[and woman] created last after all of the major animal types with an emphasis on having dominion [smarts?] over the rest of the animals and having the faculties to relate to God and have an understanding of the 'goodness' of the creation. In the heavily compressed young-earth creationist timescale the idea that man/woman are a sudden and specific creation from the dust of the ground [chimp dna?] with a seemingly tailor-made adaptation that enhances language and information processing [see article] then that no doubt will be noted by creationists. Evolutionists will say a mutation did it, creationists will say God did it.

 

[sparc872]

If they are longer then wouldn't you need more space for that?

What I was trying to say is that it would be possible for two brains to have the same mass and volume while at the same time having a different total number of neurons. The mass and volume of one neuron could be replaced with axons and dendrites, or any other number of materials that could be found in the brain.

 

[painted wolf]

rocketman: the only problem with the "creationist model" is that creation hasnt' stopped. New species are forming right now and Mankind isn't "the last overall".

wa:do

 

[fantome profane]

That's right.

It's not that it's an argument against evolution, but it does add to the standard creationist model. The Genesis account has man[and woman] created last after all of the major animal types with an emphasis on having dominion [smarts?] over the rest of the animals and having the faculties to relate to God and have an understanding of the 'goodness' of the creation. In the heavily compressed young-earth creationist timescale the idea that man/woman are a sudden and specific creation from the dust of the ground [chimp dna?] with a seemingly tailor-made adaptation that enhances language and information processing [see article] then that no doubt will be noted by creationists. Evolutionists will say a mutation did it, creationists will say God did it.

I understand. I have great faith in the ability of many creationists to twist facts and warp the truth in order to get them to fit with their ideology. And if that doesn’t work then they can simply stretch the words of their own sacred text. And then somehow with all this stretching and twisting they slam it all together and say “see, it all fits perfectly”.

One good example of this twisting is what you mention. The Genesis story has “God” forming man from the dust of the ground. So when presented with the evidence some people simply twist this story to make it say “chimp DNA”.

When you look at it what the creationists are doing is really rather sad.

(btw – which “standard creationist model” are you referring to? There are so many.)

 

[sparc872]

(somebody got it - :clap2

Oh ya...gigity gigity

 

[Druidus]

The nature of man lies not in brain size or mass but in a host of interconnected brain features.

Prefrontal and frontal cortex are foremost in this.

All that makes us us can be had with but a few alterations.

Read "Up From Dragons" by Dorion Sagan and another scientist, the name of whom escapes me.

 

[rocketman]

rocketman: the only problem with the "creationist model" is that creation hasnt' stopped. New species are forming right now and Mankind isn't "the last overall".

I said 'major animal types' not species. And while I'm not exactly sure if that's the proper term, I think that given the state of flux that classification is in at the moment, it would be hard to find a term to describe the creationist view even if we were just 'supposing' their model for the sake of argument. When I show a book to a little 6yo friend of mine I say 'Look at all the different kinds of animals in this book' because I don't know how else to say it. The creationist argument is that there were some original types/kinds/yada yada whatever. I know what they mean, I just don't know how to say it without starting a word-war. Just out of curiosity, what was the last major animal type to emerge? [if you know what I mean, if not then don't worry about it.]

By the way Painted Wolf, as far as I know, creationists don't have a problem with evolution going on as we speak, namely natural selection, mutation [viruses etc] and even minor 'speciation'. What they question is the stuff of prehistory, the idea that these smaller scale changes add up to big ones over time. A typical explanation can be found here.