Is intelligence determined by genetics?

I keep seeing this idea posed in assorted E2 nodes, and I find the idea just a wee bit disturbing. I don't know if it originated with The Bell Curve or with Ayn Rand or what. And obviously, there's a lot of room for debate here, especially since it's hard to find a definition of what "Intelligence" really is.

Our own Webster 1913 defines it as "The act or state of knowing; the exercise of the understanding." But as Ariston pointed out, those two aren't really the same thing. Knowing something is quite different from understanding it; imagine the difference between memorizing a favorite poem and comprehending the poet's intended meaning.

Further, intelligence shouldn't be linked to one's sheer volume of factual knowledge. Intelligence seems to be one's ability to use facts, to solve problems a la Mensa's IQ tests. This is why Everything isn't intelligent: it can't independently use the facts stored in the database.

So, with that working definition: Is intelligence genetic? Do the chromosomes we are born with entirely determine the maximum IQ we're capable of?

In thinking about this, I drew a parallel to muscular strength. Most would agree that certain people are born with the potential for a larger physical build. But the key word there is potential -- that the person has an advantage to develop a better musculature. But that advantage still needs to be exploited through strength training, daily exercise, and so forth. The individual isn't born to be stronger -- they just have an easier time getting there than most.

Similarly, I imagine that some people have a genetic advantage toward developing a higher intelligence, but that it's only an advantage, a potential. Intelligence, the ability to work with knowledge to solve problems, isn't instinctive to anybody. Problem solving is something that can be learned, practiced, trained, and in that way improved. If some have a genetic advantage which makes it easier for them to develop intelligence, that's to be expected. But unschooled and unused, that advantage won't amount to much.

So please, let's stop this assertion that raw intelligence is something determined at birth. Claiming that someone was born to have no better than a 100-point IQ is as silly as claiming they were born to bench press no more than 120 lbs.

The real question here is about capacity for intelligence. It's by no means ridiculous to say that someone is born with a maximum potential capacity for intelligence, just as we all have a maximum potential capacity for lifting heavy weights.

Whether these potential values are affected by genetic factors is something else again and, as far as I know, unproven. It may not be the case at all. On the other hand, one genetic subset of the human race may have evolved a higher maximum potential capacity than another subset.

If this is the case, it is no different to pointing out that the majority of south east asians are physically shorter in stature than the majority of europeans. As for whether research should or can continue, i say "why not?" If there is a pronounced difference it makes sense that it should be taken account of especially in education.

Withholding evidence for political reasons is possibly the most despicable thing i think of and has lead to massive injustices over the centuries. To indulge in such a crime merely because of current political mores would be an appalling thing to do.

If I were to set my heart on bench pressing more than 120 lbs, I would have to work long and hard. A lot of time, effort and dedication will have to go into this achievment, seeing as I am only little and not very strong at all.

I would have to have help deciding on a workout program, which will need to be comprehensive, working on the muscles in my back and shoulders separately, to counterbalance the muscle development in my chest and arms from the bench presses.

I would have to have the right equipment - a bench, a set of weights, a back belt, some dumb bells possibly. I would either need to be able to afford to buy those or to afford a gym membership.

So, before we even start arguing about whether or not my very thin wrist bones can take 120 lbs of weight, we know we need time, effort, guidance and money to even have a go at it.

Some people are like that with their bodies, some people are like that with their heads. If you supress the examination of one's mind's "fitness", you will never be able to give the little, not very strong ones the right tools to reach their highest potential (which is, and will always be, finite).

I don't like the thought of Race A being genetically smarter or better or whatever than Race B. As a Jew, the mere thought strikes terror into my paranoid little heart. But the kids who are struggling in school and not receiving an appropriate and supportive education because their teachers and councillors live in fear of being branded a racist and losing their jobs deserve better than that, ne?

whimsy: The question is not one of which prevails - nature or nurture. The question is how we can improve nurture for specialized cases of nature. This is not a revolutionary concept - there are dedicated education systems for deaf, autistic and otherwise different children. The standard education system has also in the last couple of decades been modified to accomodate children with more subtle learning disabilities and dislexia, giving them a chance to excel where one would have been completely denied them in the past.

Mr. Option: Why, then, not allow the validity of reasearch which could expand the boundaries of what we know about how different brains work differently? Because of what we might discover vis-a-vis race? Surely fearing the discovery that non-white races are less "intelligent" than the white race is a more racist supposition than just going with the flow and seeing what thruths there are to be discovered? After all, we might, fifty years from now, all "know" with unshakeable certainty that the most intellignt race is the Australian aboriginals, closely followed by the Indian sub-continent and the African races, and that white people are floundering in third place with asians and native Americans. We don't know, and we won't be able to transcend our fears of what we might dicover by suppressing scientific research.

First of all, you don't have to be so terrified by there being a gentic base for intelligence. It's not such a bizarre concept. Of course we must make a great distinction between racial differences and individual differences, but I really don't see how the racial issue ever got into this node. It is very difficult to establish racial differences of traits such as intelligence for various reasons. The most prominent is that <>intelligence must be measured by the tools of the measurer. This is different among cultures, and proved to be a crucial barrier in cross-cultural intelligence tests. The Western concept of intelligence is radically different from many tribes in Africa, for example. People without any formal education will not usually score high on Western IQ tests. Several other tests of "intelligence", better suited to 'wild environments' (for example guess what the snake will do?), prove that African tribes are more intelligent than their Western counterparts.

But enough about racial intelligence, which is not what we are talking about in this node. I don't mean to burst anyone's bubble, but intelligence has been proven, in as much as psychological tests can prove anything, that genetics play a large part, in fact probably the major part, in determining intelligence.

Usually, these psyhcological tests focus on identical (monozygotic) twins, and fraternal (dizygotic) twins. For the layman, identical twins are those which came from the same egg and sperm, and thus have the same genetic material (exactly). Fraternal twins are those which developed from separate eggs and sperms, and thus are related genetically just like any two siblings (roughly a quarter of their genetic material is identical). In all the tests I have heard about, a comparison was made between the intelligence of fraternal twins that live in the same household (so that the effects of the environment on their intelligence are approximately the same, or at least very similar), and identical twins separated at birth. In every test I know of, whatever the method used to measure intelligence, there was a much higher correlation between the identical twins than between the paternal twins, even though the identical twins were brought up apart in (sometimes drastically) different environments.

You are free to make your own deductions. The current opinion of the scientific world is that intelligence is more affected by nature than nurture. I know that this may be an uncomfortable thought to many. But life is not always what we want it to be.

Genes define capacity for intelligence.

My genes differ from that of a hamster. I am (generally) more intelligent than a hamster. The genetic difference between me and the small, furry mammal is responsible for this difference in intelligence. I like to think that even if the hamster had the same advantages in education and stimulation, I would still come out tops in the IQ stakes.

The real question is whether or not the natural variation in the human population is significant, or whether cultural effects dominate.
I believe the latter.

Nobody is surprised if I say I share cognitive characteristics or aptitudes with my immediate family. I take after my parents. I was lucky, and had more opportunity and encouragement to stretch my mind and pursue my interests. For me and my genes, life is good and my genes get to express themselves. Many other people don't get the opportunity to develop their mind. I reckon this latent capacity completely outweighs any genetically-linked variation of performance in simplistic IQ tests.

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