Evolution of Intelligence in Jews

In a test with no capacity to measure anything but how well you've been educated by your culture? I doubt that very much. Exactly how many individual cases are we talking about here, where a child is adopted into an entirely different culture and education from their birth parents, and IQ tests are able to be administered to both, at the same age? 10 cases? 20? Then it's not clear to me what we're arguing, I guess. Could you restate your position? Mine is that IQ tests measure nothing but flexible, improvable mental skills, not an innate, static general intelligence factor. But nobody does pass through the same education. Everybody's education is substantially different. Same school, same teacher, same text - it doesn't matter; everybody has a unique educational experience. So I don't see what the relevant of your point is, here. The confounding factor that everyone's education is different would obscure any individual difference in knowledge retention.And that kind of retention is just memory, anyway. Memory can be improved with use and training. There are no such factors that are known to exist. They are only purported to exist based on certain interpretations of the testing, based on certain assumptions about what factors can be controlled for. Those interpretations and assumptions are very much in dispute. Because genetics don't control everything. Some things are not genetic. And in the face of a lack of any evidence for a "smart gene", I don't find it terribly responsible to assert one. And it's even more irresponsible to assert genetic differences in intelligence between different racial groups, or between men and women. And almost universally the most vocal proponents of these completely unsupported speculations turn out to have a vested interest in the abandonment of efforts to improve educational opportunities for minorities and women.I'm not trying to impeach your statements with the agendas of others. I understand that they're surely not related. But the burden of evidence for what you propose simply has not been met. Has not even come close. Is zero, in fact. I maintain the precise opposite, in fact - that human intelligence is precisely identical to other aspects of biological behavior, in that while, at best, genetics sets very wide limits, individuals are far more constrained by their environment and upbringing. So constrained, in fact, that in the majority of cases, the genetic limits aren't even relevant, and may not even be detectable.

I didn't, and I'm not going to; I use it as it would generally be understood in conversation without definition. I use IQ when I want something precise.

It makes utterly no difference. Correlation testing reveals what part of the variation in IQ scores can be explained by biological inheritance. The number of cases in which this has been down is sufficently large for the results to be distinguishable from random chance to a very, very high degree of confidence. The word static is the one I'm objecting to.I think intelligence has a strong genetic component; but that does not mean that x points of IQ come from genetic and y from the environment. It means that the was the environment produces intelligence is shaped by the genetics; just as with everything else that is genetic. Studies show that IQ is strongly heritary, around 50% of variation in IQ scores being biologically heritary in children and 75% in adults. I consider IQ tests to be a good measure of intelligence; as the word is used in general conversation - I believe this to be so because IQ tests pass criteria for being a valid test (your score on one IQ test is a very good predictor of your score on another) and strongly correlate with - and predicts - the characteristics we would expect of intelligence. If what you assert to be so was the case; evolution couldn't happen. Thus you are wrong. I couldn't care less, frankly.

How many cases is that, though? And what is the degree of confidence? Oh, come on. That's a ridiculous statement at best, and I think I deserve a better rebuttal than that by now. I've madwe a good faith effort to address your points as you've presented them, and it's quite disappointing to see that you apparently aren't interested in reciprocating.And can you explain how these two statements are not directly contradictory?

The degree of confidence will vary between individual studies, those I read as an undergraduate had confidences of between 95% and 99%. Taken as a whole, the degree of confidence is much higher than that. Meanwhile there is not a single study that shows the heritability of intelligence to be zero; not one. The supporters of the blank slate solely rely on criticising IQ studies, or on emotional appeals - such as the one you made in your last post. You claimed genetics was insignificant in an organisms success, yes? That claim can't be true at the same time as evolution. If you think it can, please explain how?I see your position as equivalent to a claim that intelligence did not evolve; I do not see how you can both claim that intelligence does not possess a strong heritary component and that it evolved - the two positions are contradictory. Ok, let me try to explain: I shall use maths because that's where my background lies. Imagine a non-constant function f(x); suppose the result of f(x) is what we are interested in but there are two factions: the f-ists and the x-ists - the f-ists claiming that the result is dependant on f, the x-ists claiming that it is dependant on x. Both are trivially and obviously wrong. The result depends on both.Such is it with nature and nuture; genetics has a strong influencing factor, but just as f can only work with it's input x so can an organisms genome only work with it's input; specifically, the environment.You can't determine that any particular point of IQ belongs to the nature or the nuture - such a notion is, in fact, incoherant - you can only look at how much of the variation (within the sample you have) is determined by each using suitable statistical techniques.

Jack, this isn't a hard question. How many cases are we talking about? How do they control for cultural effects? Well, it wasn't very hard to find a study that disagreed with you: Just a moment...

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Estimates based on phenotypic correlations between separated monozygotic twins”usually considered to be the most reliable kind of estimates”are vitiated by systematic errors inherent in IQ tests, by the presence of genotype-environment correlation, and by the lack of detailed understanding of environmental factors relevant to the development of behavioral traits. Other kinds of estimates are beset, in addition, by systematic errors arising from incomplete allowance for the effects of assortative mating and from gene-gene interactions. The only potentially useful data are phenotypic correlations between unrelated foster children reared together, which could, in principle, yield lower limits for e2. Available data indicate that, for unrelated foster children reared together, the broad heritability (h2) may lie between 0.0 and 0.5. This estimate does not apply to populations composed of children reared by their biological parents or by near relatives. For such populations the heritability of IQ remains undefined.

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The only data that might yield meaningful estimates ot narrow heritability are phenotypic correlations between half-sibs reared in statistically independent environments. No useful data of this kind are available.

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Published analyses of IQ data provide no support whatever for Jensen's thesis that inequalities in cognitive performance are due largely to genetic differences. As Lewontin (8) has clearly shown, the value of the broad heritability of IQ is in any case only marginally relevant to this question. I have argued that conventional estimates of the broad heritability of IQ are invalid and that the only data on which potentially valid estimates might be based are consistent with a broad heritability of less than 0.5.

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Or from another study:

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Scores on the Wechsler Intelligence Scale for Children were analyzed in a sample of 7-year-old twins from the National Collaborative Perinatal Project. A substantial proportion of the twins were raised in families living near or below the poverty level. Biometric analyses were conducted using models allowing for components attributable to the additive effects of genotype, shared environment, and nonshared environment to interact with socioeconomic status (SES) measured as a continuous variable. Results demonstrate that the proportions of IQ variance attributable to genes and environment vary nonlinearly with SES. The models suggest that in impoverished families, 60% of the variance in IQ is accounted for by the shared environment, and the contribution of genes is close to zero; in affluent families, the result is almost exactly the reverse.

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Just a moment...Funny - I can't seem to find the "emotional appeals" in these two abstracts. Maybe you can help me with that? Um, I've claimed no such thing. I urge you to go back and read my posts so that you have a clearer idea of my position. To repeat - for the majority of individuals, performance on IQ tests is determined not by inherited genetic limits, but by life experiences, social factors, nutrition, and upbringing. Exactly as your ability right now to run the mile is limited far more by your exercise history and almost negligably by any kind of genetic factor. Right, because you've assumed a function that is non-constant. I'm not impressed much by an analogy that obviously assumes its conclusion, I guess.

An article which does exactly what I said: it provides only criticism of studies showing heritability in IQ scores; not any direct evidence of a zero correlation. Further, in the very part you cited it states "I have argued that conventional estimates of the broad heritability of IQ are invalid and that the only data on which potentially valid estimates might be based are consistent with a broad heritability of less than 0.5." Less than 0.5 is not zero; and is not insignificant. I can't get to the full text to comment properly; but on face value of the section cited it has the very interesting claim that heritability increases with SES not that heritability is zero. What's more the study was done with very young children - exactly the group that show least heritability in other studies. That's the same thing stated differently. You claim that for a typical individual genetics is not significant in determining ability. Criticising an analogy provided as explanation because it does not form an argument is ridiculous in the extreme.

I'm sorry that I can't provide a study that proves the impossible. Demonstrating an absolute zero correlation is statistically impossible. It's only possible to show positive or negative correllation that is beneath an arbitrary significance value.The first paper makes a pretty convincing case that whatever corellative values exist in this case are below that significance value. You claim that 0.5 is not insigificant, but that paper seems to state the exact opposite.You tell me who to believe, I guess. You could improve your case by actually supporting your statements, such as "0.5 is not insigificant." Assume I'm as ignorant as you like to pretend I am. Yes. That is not synonymous with "genetics doesn't exist" or "evolution is impossible" or whatever other ridiculous strawmen you care to offer. My point was that your analogy explains nothing at all, because it isn't analogous to the situation at hand. If you'd care to try again, with an analogy that actually reflects the relevant situation and isn't obviously stacked to prove a trivially obvious but irrelevant point, please be at your leisure to do so.

Reading through this interesting discussion, I take it that your point, Crashfrog, is not that high or medium or low intelligence is not inherited, but that IQ tests don't measure intelligence? I guess you would say that there is no standardized test that does?

No. What they measure is your skill at test-taking, which, in the best possible case, is as close a measure of your intelligence as your score on the mile run is a measure of your cholesterol level.In other words - much as your score on the mile run is much more a measure of how many miles you've run in the past than an assessment of your genetic ability to run, IQ tests are much more a measure of how many tests you've taken (and other related educational activites) than the presence or absence of some kind of "smart gene."I'm not saying that the functioning of our brains has nothing to do with our genes. But that's a long way off from asserting the existence of multiple alleles of some kind of intelligence gene or genes. The genetic basis for intelligence might very well be only two alleles - one normal gene that promotes normal brain function, and one or many degenerate alleles that encode some abnormal, detrimental brain structure or chemistry. How could a test measure something we can't even define?

That's right. But if one limits the definition of intelligence one might be able to come up with some kind of test.Though this is not quite the same, I do think that certain aptitudes or talents are inherited. My idea is not based on anything scientific, just personal anecdotal evidence. For example in my family (father's side), there appears to be an aptitude for writing. With my wife's family (her father's side), the aptitude is for drawing. The ability to draw is particularly interesting, in that it does seem to be largely innate. I can't draw at all, even though I've tried very hard, and neither can anyone else in my family (brothers, etc.). However, just about everybody in her family can and very well too. Her father was a professional artist. However, we can't claim any cultural influence from him, since he died when she was a small child without ever having known him.So there must be a "drawing" gene. There might even be a "writing" gene and "music" gene.

"Thinking," said Wittgenstein,"is essentially the activity of operating with signs."Intelligence might be defined as the ability to think. High intelligence means you can think very well. So, by the above definition, that person who can "operate with signs" the best (the most accurately) is the most intelligent.

Different people use intelligence in different ways. The same person uses intelligence in different ways based on context.If I could figure it out based on the context of this thread, I wouldn't have asked. Without some attempt to at least pose some restrictions on the word "intelligence" so I can figure out what you're talking about, I'm not even certain the discussion you're having is useful.Can you give it a try?

BS. If you can hold a pencil, you can be taught to draw. Maybe not well, but you can be taught to see shapes, forms, and lighting in terms of lines and shaded areas, and produce those on paper. After all, you can see drawings, right? When people draw, you can process the image? Of course you can. Thus, you can be taught to produce such images, because your brain already understands how to interpret them. I've seen some pretty hopeless cases learn to draw.When people say "it's genetic", what they mean a lot of the time is "I'm not any good at it, and getting better would be a lot of hard work, so it's just much easier for me to posit some genetic lack beyond my control that excuses my failure."

What I'm saying is that there is such a thing as inherited talents or at least aptitude.