How diffrent are peoples brains from each other?

Genes are widely overrated in what they can tell on living beings.
The genes IMHO dont carry the information itself - this is just not possible as its not enough genetic code available and used for this.
I came to the opinion that the genetic coding resembles more a directory, the catalog of a library than the library itself in whole.
Where is the library? Everywhere. The fact that all life on earth descended from one common source makes it thinkable that living beings can utilize all code which is around.
Humans reproduce much to slow to be able to adapt to changes in climate or to viri fast enough by mutation and survival of the fittest. But humans in reality adapt fucking fast it shows. Where does the information come from? Perhaps humans are just lending the code from beings, flies, bacteria, whatever, which are able to adapt much faster if the needed information is not available somewhere from ancient times of the development of life?

This should be enough reason not to use antibacterial soap anymore.

Eating wouldnt be fun this way I guess, you couldnt eat so fast as you vomit.....

Do you have strong xenophopic tendencies unionised or a you a convinced user of antibacterial soap?

A big reply :)

Wolfram - to answer your question:
Not much is known about genes that do our 'thinking'. Instead, I should think that 'our thinking' is done by all the rest of the genes, i.e. the cellular function genes (which govern the synaptic crosslinking behaviour etc - which surely has some bearing on the ability to think)


Regarding your cDNA microarray technique. First, for the uninformed, it essentially a technique that enables you to quantitatively fish out expressed genes from the whole genome (i.e. all the chromosomes combined, which contain about 40000 genes in h.s.). Genes are differentially expressed in different tissues/organs, hence the subset of expressed genes is some kind of signature for different organs/tissues ('expressed' meaning the translation from gene to protein - which does the job, not the gene (DNA) itself). This subset may for instance vary under certain conditions - i.e. if you administer a certain drug affecting certain target organs/cells. It also varies if mutations/alleles are present. At last, it varies according to enviromental conditions. I.e. starving/dehydrating organisms have different expression levels in various organs.

So back to your question: cDNA microarrays unfortunatily are often rather statistical, in that one can only draw definitive conclusions once a number of samples have been analysed, and a mean has been taken.
To compare one individual to another is unfortunatley not enough, one would have to analyse a certain number of individuals from group A to individual from group B, where A and B have the different phenotypes (i.e. intelligence) in question.
So if one were to do this, it would be hard to predict the outcome. Statistically, one will probably find a gene or two that shows a slight increase in expression in group A, while not in group B. But cDNA microarrays are a fickle technique, subject to a lot of variation, false positives, and artefacts (which is one of the reasons why it is not as pathbreaking as it should be if it was working perfectly).

I remember a presentation about the ageing of brains - and they did just that. Brains from various age groups were analysed via the cDNA microarrays, and expression patterns deduced. Above the age of 60 or so, a number of repair genes were switched on heavily, while others were downregulated. Overall, a trend could be seen, but regarding the individual, much variation persisted. There are one or two well known Nature papers on this, I can dig them out once that person is back who's on holidays right now.
Anyway - I was amazed by the complexity that ageing just itself creates - when I say a 'number' got up or downregulated, that translates to HUNDREDS of genes whose expression patterns changed. They all interact between each other, so don't you think it will be rather hard to pin down particulars?

In a way, this is why molecular biology and biochemistry went all fair and well - until now. Now we are hitting the complexity limit, and all this multitude of interactions is extremely hard to separate into components - and to UNDERSTAND. This is why a lot of molecular cell biology that is done these days is a pile of crap - they rip things out of the context and make grand deductions - which hold in the specific setting, but not in the overall organism.
Hence I am getting out of MCB - the way things are running there ain't just convincing me! Unfortunately I don't have a solution to the problem either - either a Nobel would be ensured




To comment on the various points made:
Org/Unionised: Genes ARE overrated on what they can tell on the individual. However - what really matters are not the genes (genomics) but the proteins derived from it (proteomics). Genomics is sorted to a large extent, but proteomics- it is just about to be elucidated. And it will take a long time to understand this (see the complexity problem above). You know, a monkey has an equal number of genes to us. Most are identical to ours. What makes us different? It's the interactions between the proteins, the transcription factors, repressors, enhancers and so on. Subtle mutations here and there (making up 0.1% of the overall change compared to monkeys), all collaborating and interacting between each other, make us what we are. How the hell are we ever going to understand all this? I just don't know.

As to foreign genetic material - about HALF of our human genome is of VIRAL origin, all inactive. Some may be active, but we just don't know. There are things called transposons, self-replicating pieces of DNA that just sit within our genes and replicate. There are many things we do not understand. Particularly - why hasn't the human organism evolved to kick out those 50% of useless material? Maybe because, it is, by some unknown means, sometimes necessary for survival? There are many hypotheses of course. Still I wouldn't attribute the adaptability of humans to those things. They are on a level below that (i.e. the source code behind a few functions). The adaptability is, IMHO, mainly down to intelligence - i.e. to use furs to live with cold, to build shelters if necessary and so on. Other than that, humans are as adaptable as any other mammalian species.

I don't follow this whole library thing. I always shy away from analogies becuase people often use them to deduce things from the analogy, BUT often it is just not possible. So maybe your analogies need refinements. How about just sticking to facts?

JohnWW: The changes you describe are morphological/phenotypical, so hardly applicable to molecular analysis of brain tissues! Unless the molecular change of course causes a major change in morphology (which is not the issue here anyway - cDNA microarrays work on a molecular basis). Remember - both Einstein's and Lenin's brains were analysed, cut up into sections etc - and no difference to any other 'more common' people could be found. Goes to show that the genius of Einstein is on a much finer level, i.e. the molecular one!

[Edited on 28-8-2004 by chemoleo]

chemoleo, very interesting, I lack the biochemical knowledge to talk on details here, my approach is one derived from the theory of information.

Evolution of life, buildt on billions of years and gathered immense amounts of information has every mechanism known to man utilized and quantummechanics are not neglected and I bet my ass we will find some day a creature which utilizes a kind of cold fusion - it would astonish me if not. (maybe we all utilize something like this and just havent seen it by now).

Most fascinating to me are the strong hints that our brain, our consciousness (so avail) is working on mechanisms of quantum mechanics or even behind.
This proves that evolution was able to get highly NON-INTUITIVE mechanisms working.
And thats something. Oh my.

One very ..

...

About the massive amount of unused DNA, perhaps they just evolved to become immune to our rejection system, going from the number of infections which can easely kill you if not treated with modern medicine.

Although it could be that they are just not used at the present since ,from an evolutnery perspective, human's have only existed for a very small time and we arent really that diferent from big shaved circus monkeys anyway :p

From a totaly diferent perspetive though, I was going through 'new age' sites(mainly christian propeganda though, where some think that it may be soem sort of stock DNA containing actual information.Seems highyl unlikely(suported by them saying god put it there).Going from how some animals do have quite advanced 'instincts' it might well be possible.Either that or animals are a lot smarter than we think

Far as life ans human existance is concerned there much to be known compared to what we know. I feel same even for other natural sciences.

Anyway , on topic. The human brain Evolves in time as it grows. And thats not because of the genetic code. That depends on the conditions one lives in. There are more than 50% brain cells formef after the birth. and thats not the end of the story. The connections between the cells and their(connnections) intensity varies.

Till the first 6 months of childs life he doesn't even has psychomotor control, all the actions that it do is reflexive. In fact it's easily understood in the sence that a child does have an abstract system embedded in it's brain which might be commen(it's not far as I THINK), but the parameters of that systems are ALWAYS defined by the environment.

Think of language for instance. It's a very complex way of communication and a VERY abstract concept, yet a two year old child learns to extant that not a super computer can be traied to as of now. Linguists feel that there is an inherent laguage model in the child that adapts itself to the languge of surrounding and hence all languages of the world are same at a level of abstraction.

So is true for human nature, the set of emotions, the set of motivating factors, the set of drives and even the set of values at times. But that as far as we go. The exactness is UNATTAINABLE an will remain so.

chemoleo: Probably I had the right analogy of abstract system and undefined parameters, for genomics and protenomics,right? BTW far as I remember there is about 2% difference in the gene pool of chimps and humans(homo sepian sepian).

Genes only tell about the system(the organism) at some level of abstraction but never about parameters.
I think before I end I should give an example so that those who are not much fameliar with terminology can get the meaning of what I've been describing all along.

suppose there is a mathametical function and you want to know it. you looked at the gene set and you get that the function is of the form f(x)= Ax+B
So you got the function and hence a lot of properties of it as well(continuos,differntiable,monotonous...........) but YOU DON"T KNOW THE FUNCTION untill you know A and B.

thanx to those who tolerated it till they finished reading

No offense but your gravely exagerating.For one thing the brain in a human has been in development for milions of times longer than a supercomputer.Also computers are actually smarter than your giving them credit for

On a more abstract level though ,going with the(ie)myers-briggs system for personalety classification there's qutie a lot that depends on the base wiring of your brain(like which parts are predominent)which would depend on your DNA.If your an 'auditry' person you were wired that way and there is'nt anything (current ) technology can do to change it.

Hmm, that latter statement seems to contradict the former?

Anyway - I fully agree that the brain is pre-wired to adapt to language and so on. This is definitely coded in the DNA. What happens during your development lateron is an entirely different story. You may have noticed that identical twins are most of the time not 100% identical. I know two that are 5 cm different in height. One has a broader face than the other. All down to environmental factors, not the genes.
Conversely, behaviour is sometimes preprogrammed. Identical twins separated at birth often end up doing similar professions. If one however ends up as a farmer, and the other as an accountant, then massive differences between the two can be visually seen - again the environment taking a toll. Yet interests etc often overlap, even then.

Tauren- regarding your function analogy - it holds and it doesn't. It holds in that there are a lot of variables we don't know, while we know 'x', the sequence of the genes. However - the function is vastly too simple of course
I.e. A my be iterated (feedback) by B(y), which in turn is affected by a myriad of other genes and their variables. Personally I never liked these analogies...as they are misleading, and give you the illusion of understanding - which is just not there

The thing is, genes are only genes (genomics). They don't do much more than making ONE protein. BUT- that ONE protein may interact with hundreds, if not thousands of other proteins - which all affect each other in turn (proteomics)! And these millions of protein FUNCTIONS cannot be predicted, unlike the protein sequence from the gene!
This is today's problem in understanding life.

And I don't see a solution to this either - except the full and accurate predicatbility of all protein structures and their functions. Then the only entitity understanding all this at once will be a BIG computer, and not a human brain

Chemoleo

I was actually saying that either it's usefull for something thats not immidiatly aparant/neccesry or it's just parasitic and serves no real purpose.Personally though I think that they are similer to animal instincs and that much(most)of it it instincs we dont need right now.

About the computer thing: despite having a large time handicap theyre stiller very smart(well IMHO)

[Edited on 18-9-2004 by IvX]