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Intelligence is Inherited
codeButcher writes: "Now you can blame it on your parents! NewScientist.com reports on a study done on twins, that determines that IQ [and lack thereof then too, I suppose] is inherited. Quote: The finding suggests that environment - their own personal experiences, what they learned in life, who they knew - played a negligible role in shaping it."
In practice, IQs measure only one skill: how well you do on IQ tests.
(Incidentally, this isn't sour grapes -- I don't know what my IQ is exactly, but I'm told it's within a fraction of the top 1 percentile. And I don't consider myself particularly intelligent either.)
In 1869 Francis Galton wrote a book called "Hereditary Genius" on this very subject. It's the first quantitative analysis of the human mental ability. He studied scientists, poets, politicians and many more people, classifying then into nature vs. nurture. In the end he concludes genius is hereditary in humans. Many people consider this book as the creator of the nature vs. nurture argument. He puts forth a great deal of stats in the book, something I find many case studies to be missing.
...think twice before shouting out "stupid parents" in the future, eh?
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No I didn't say it would work. I said it was a good idea. Ideas never work by themselves.
This sort of finding bothers me. It bothers me in the same way as did a news article a couple of weeks ago reporting that a women was offering something on the order $10k for primo sperm from a Stanford student with certain physical characteristics.
Given the knowledge of this genetic connection, we should in principle be able to start a breeding program to increase the average IQ of the human species.
But is this necesssarily a good thing? I'm not convinced that a high IQ is the primary trait needed for human survival. (It's not a bad thing in of itself... some of my best friends have a high IQ. grin.)
We've come pretty far as a species responding to a number of adverse environments trusting in good old Natural Selection. If we start intentionally selecting out a certain set of genes as especially desirable, what's to stop us from creating a hyper specialized race of savants that do great in math and music, but don't have the ability to bind people together to a common goal?
I guess what I'm saying is that I've seen what effect overbreeding has had on the canine species - especially when humans have gotten involved. What will happen to our species if we follow that path?
In illa quae ultra sunt
... they won't believe you at all. At that age, all parents are stupid - I know mine were. Of course, they started to get more intelligent when I hit the 20-year old mark. I can only conclude that intelligence is increased by continous contact with intelligent young people.
"Trust me - I know what I'm doing."
- Sledge Hammer
Ah. Touche. I guess, being an Israeli, I should have remembered that. *sigh*
rJames.org - illustration
Hmm what song is that from, I think it was weaser??? I wonder how much truth there is in that. Are we breeding dumber Americans? Sure seems that way when I get on the road and people can't figure out how to use their turn signals properly or how to drive....
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You also have to think to future generations as well. Say you had a child that wasn't breastfed, was exposed to lead paint and mercury vapors, fetal alcohol syndrome, etc. That child's DNA (likely) wasn't affected by their environment so should they then have children and breastfeed them, not drink/do crack during pregnancy, live in houses built after 1977 with no lead paint, etc. Their kids have every likelihood of achieiving the a much higher tested IQ level than the parents.
This is important news, since many consider African Americans to perfrom worse on IQ test than caucasians. But if you correct this data for the environmental factors attributable largely to poverty and a much loewer rate of breastfeeding among African Americans, you'll find that it's not genetics that causing these lowers scores for African Americans but primarily enviroment.
(to a lesser extent you may be able to find that asians have a higher tested IQ due to their much greater consumption of fish (rich in the same faty acid as found in breastmilk than improve brain growth) than other cultures.)
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The twins shared environments, means researchers can separate genetic and environmental factors.
This means that the subjects were in the same environments and makes genetics the dependent variable. This doesn't make any indication of environmental influence on intelligence. As I understand the article, they are stating that in this experiment, environment is not significant since both of the twins had the same basic environment.
"It's extraordinary how similar they are," he says. The finding suggests that environment - their own personal experiences, what they learned in life, who they knew - played a negligible role in shaping it.
There's no point in being grown up if you can't be childish sometimes. -- Dr. Who
There is no good quantifiable measurement for intelligence.
You mean there is no generally accepted definition of intelligence.
Once you reach a conclusion as to what skills represent intelligence, it is quite clear that a test evaluating those skills is a very short step.
I'd never have guessed. I thought it was just a coincidence that most humans seemed to be more intelligent that members of other species. It's amazing what these scientists discover.
-- SIGFPE
Oh yes. Stephen J Gould is well known as being completely unbiased in his expositions. I mean there's no way Gould would let his political ideas have any influence on what he reports as fact in his articles. I've read a dozen books by Gould and I still have no ideas where along the political spectrum his opinions lie.
-- SIGFPE
Not so, for example in a field like paleontology there is such an incomplete fossil record that there is plenty of room for debate. For example there's the question of how recent the most common ancestor of all humans alive today lived. Some give more recent dates than others depending on how the evidence is interpreted. But even before reading what Gould has to say on the matter you can guarantee he'll settle for the more recent end of the spectrum (barring the views of cretinists) because that's more convenient for his political views. Maybe there will come a day when we'll have a pretty accurate handle on when this human lived - but that's quite a way off and anything published now on that subject is likely to be a collection of facts with gaps between filled in by speculation and opinion.
For a more concrete example check out Wonderful Life where he makes his strongest case that there is no direction to evolution (a thoroughly bizarre claim IMHO). Armed with this opinion he makes a great many suggestions about how various pieces of fossil evidence should be interpreted. It turns out that the great majority of these claims were actually demonstrated likely to be false in a relatively small time (do a web search on the names of the various fossils that he talks about in the book). A little thought will reveal the real reason why he argues against a direction to evolution.
However I'd hate to put people off Gould. Much as he pisses me off no end he's very worth reading and The Mismeasure of Man is an excellent book. Same goes for Wonderful Life.
-- SIGFPE
Why would you think that an ability to communicate is somehow indepedent from observer bias, such that we cannot measure artistic ability -- which you link to communicative ability -- because there is too much observer bias? Isn't observer bias the heart of communication? And thus wouldn't any attempt to measure such ability independent of such 'bias' be an attempt to measure nothing? And thus not at all surprising when we fail?
Or do you suggest that I can speak perfectly good German even if no so-called German-speaker can understand me? Or that what I speak can be classified as good German or bad German without regard to how Germans are speaking?
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The nature nurture debate has raged for centuries in respect to intelligence. Ever since Darwin's cousin Francis Galton proposed his theories of hereditary intelligence.
At first glance, it seems neat that these guys did a study on twins. You might think, "wow, what a great approach." You'd be right, then you'd hopefully realize that other people had these ideas in the past, and they did the right studies and came to the right conclusions.
When Thomas Bouchard was in charge of the Minnesota Twin Studies, he and his colleagues compared twins raised together and apart.
Bouchard and colleagues tested 56 pairs of monozygotic (identical) twins who had been raised apart and compared them to hundreds of identical twins who had been reared together. The twins were tested on dozens of capacities. This approach allowed them to examine spatial ability, verbal ability, mathematical ability, personality, etc. Rather than the antiquated "g" or general intelligence factor.
So, here's a study with many more subjects, much better comparisons, and more detailed data. Here's the cool part: if you correlate the scores of twins on the Wechsler Adult Intelligence Scale (WAIS) (the standard IQ test in the US) and Ravens Progressive Matrices (An allegedly culturally unbiased test of reasoning skills), you see a 65% (WAIS) or 50% (Raven's) agreement among scores of twins raised together, and among twins raised apart, the WAIS scores are about 35% in agreement with nearly the same 50% agreement on Raven's scores.
What does this mean? Well, it means that even in the best cases, IQ scores are about 50% hereditary. In addition, the big drop off between WAIS scores indicates that environment has an important role in intelligence. Given that most of the twins were raised in similar middle class families (who adopt kids), the estimates of the role of environment are probably inflated.
That being said, the study mentioned in the story focuses primarily on brain structures. This pisses me off. One of the lamest things about current cognitive neuroscience is the common misunderstanding of the difference between structure and process. Given the little we know about how the brain works (yeah, we're getting good info about the molecular level, and we know in general what larger regions like Broca's area are responsible for, but we have woefully little info about how these structures actually work), idiot PR people take brain findings and blow them out of proportion.
The fact is, if you want to talk about intelligence, you have to talk about behavioral measurements. Looking at structures can, at best, tell you if something is wrong. So, yeah big deal, major structures are heritable, given the fact that environment has been shown in better studies to play a key role in intelligence, we shouldn't rely too much on these findings.
Bottom line: Yes of course nature plays an important role in intelligence. You'd have to be an idiot not to realize that. This study is not groundbreaking. Moreover, the headline of the article is sensationalistic and only a half-truth. Environment does play a role in intelligence. My god, meet a person who ate lead paint as a kid and you'll realize that.
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Excerpts to prove it:
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The twins _shared_environments_ (my emphasis), means researchers can separate genetic and environmental factors. (Huh?)
The researchers found that certain regions of the brain were highly heritable. These included language areas, known as Broca's and Wernicke's areas, and the frontal region, which, among other things, plays a huge role in cognition.
"It's extraordinary how similar they are," he says. The finding suggests that environment - their own personal experiences, what they learned in life, who they knew - played a negligible role in _shaping_ it (emphasis mine).
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Doh. Same environment + same wetware what do you expect? So what if wetware isn't shaped that much by the environment.
To prove inheritance shouldn't they use different environment + same/similar wetware?
Conclusion: stupid researchers|journalist.