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Assorted links
1. New Freakonomics study guide, explained and downloadable here. Elsewhere on the Steve Levitt front, he argues with Roland Fryer that black and white kids have roughly the same mental abilities when measured at age one.
2. Google map of Mars, hat tip to Yana.
3. Here is a new cost-benefit study of the war in Iraq, from a hawk-friendly point of view. The authors are Steve Davis, Kevin Murphy, and Bob Topel; I'll let you know more once I've read it.
Posted by Tyler Cowen on March 13, 2006 at 01:25 PM in Books | Permalink
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I thought that there weren't any reliable tests for IQ before the age of 3 (or is it 7)?
Posted by: anon at Mar 13, 2006 1:37:35 PM
anon writes:
[I thought that there weren't any reliable tests for IQ before the age of 3 (or is it 7)?]
From the abstract: [....Using a newly available nationally representative data set that includes a test of mental function for children aged eight to twelve months....]
Levitt doesn't claim it's an IQ test. It's a test of mental function, which is a far broader category of tests.
Furthermore, there are some theories that neoteny (the retaining of infant/child-like characteristics into maturity, such as large, round heads in comparison to body size), is one possible mechanism by which evolution increases mammilian intelligence.
Here is wikipedia on neoteny, under the sub-heading evolution:
http://en.wikipedia.org/wiki/Neoteny
[...To be neotenous needs a realisation of its condition. It effects all the primates. Most of the chimps studied, for example, lose their neoteny at about 2-3 years. Most adult humans lose their neoteny between the 14th and 17th year. But in some, neoteney remains; and that is a quest to learn and get better and find out things.
Neoteny is not the only contributing factor affecting maturation in species that may have undergone neotenous changes over the course of their evolution, and its actual involvement in the following examples is not well understood:
flightless birds - physical proportions resemble those of the chicks of flighted birds;
humans - with traits such as sparse body hair and enlarged heads reminiscent of baby primates; and
dogs - which share many physical features with the immature wolf.....]
Here is a Stephen J. Gould quote:
"[A] general, temporal retardation of development has clearly characterized human evolution. This retardation established a matrix within which all trends in the evolution of human morphology must be assessed." (Ontogeny and Phylogeny, Belknap/Harvard, 1977).
http://www.starlarvae.org/Space_Brains_Neural_Neoteny.html
If neoteny (keeping infantile characteristics into adulthood) is really one of the most important mechanism by which mammilian intelligence is increased, then it is kind of a tautology to say that infants (an age at which differerences in neoteny have hardly had a chance to show) have the same mental abilities.
I'd bet that the chimp/human difference in mental funtion among infants is less than the chimp/human difference in mental function among adults. Why didn't Levitt do that experiment too?
Posted by: PJGoober at Mar 13, 2006 4:05:00 PM
Wow, PJGoober, that's quite a post you have there. Especially those last two sentences.
Biological determinists these days generally ascribe to Charles Murray's working thesis that the racial gap stays roughly constant over time (within and between generations). It shows up as early as 2-3 years old (not 14-17 as you suggest that neoteny implies). This study, right or wrong, is in direct conflict with that theory.
Posted by: Matt at Mar 13, 2006 4:45:37 PM
Matt writes:
[Biological determinists these days generally ascribe to Charles Murray's working thesis that the racial gap stays roughly constant over time (within and between generations). It shows up as early as 2-3 years old (not 14-17 as you suggest that neoteny implies). This study, right or wrong, is in direct conflict with that theory.]
You mischaracterize: 1)No one is a 100% bioligical determinist, they would rightly be ridiculed 2) Bell-Curvers (and practically any intelligence researcher in existence) realize that the racial gap in IQ widens with age. Here are a few quotes that acknowledge this. Can you find any quotes that show ANYONE, Bell Curver or not, who believes that the racial gap in achievement/IQ (studies by liberals will probably say achievement instead of IQ) doesn't widen with age?
[Ability gaps open up early, often by ages one or two, and as a result minorities enter school
with substantially lower measured ability than whites. The black-white ability gap widens as
the children get older and obtain more schooling.....]
and
[Children of different racial and ethnic groups grow up in strikingly different environments. Even after accounting for these environmental factors in a correlational sense, substantial test score gaps remain. Furthermore, these gaps tend to widen with age and schooling: black children show lower measured ability growth with schooling or age than white children.]
http://www.ucl.ac.uk/~uctppca/disc.pdf
Here is something related which leads to the same conclusion: (because people tend to inherit thier genes from people of the same race)
[The evidence indicates that the heritability of IQ increases with age from early childhood (with heritability around 0.4) to later maturity (over 0.7)]
http://www.cogsci.ecs.soton.ac.uk/cgi/psyc/newpsy?11.106
Thus, the younger humans are, the more alike they will be in intelligence.
As different humans age, genetic differences in neoteny expression (how baby-like, and for how long, it's a continuum, not an on-off switch as you gleaned from the crappy wikipedia quote I posted) start causing differences which widen with age. When viewed this way, the theory of the neoteny-intelligence connection does not imply that the racial gap would start at age 14-17 (You took a long, unwarranted leap).
The wikipedia quote I gave is a little hard to understand. When it says "neoteny ends at 14-17" it means that neoteny is less pronounced (ie: 14-17 year olds have longer limbs and greater musculature, but all adult human's still keep the generally round babyish heads of human infants far more so than adult chimps keep the round babyish heads of chimp-infants) . Neoteny isn't something that is either on or off. I repeat, all human beings, adult or child, have some aspects of neoteny. Using the dog-wolf example, dog puppies and wolf puppies act more similiar than adult dogs and wolves. Adult dogs act more like puppies (playful, etc...) than adult wolves, thus dogs are more neotenous than wolves.
Summary:
1) Racial gap in IQ (or achievement if you're a liberal) increases with age. this is a well acknowledged fact.
2) Differences in Neoteny expression with age could account for this. This means that smarter people keep more baby like traits longer, and more baby like traits permanently (who learns better, the young or the old? Neoteny helps us keep the brain plasticity of the young). Neoteny is not an on or off trait. If you think neoteny ends as opposed to gradually diminishing with age and never totally ending, just feel the shape of your head, and you'll see it's pretty much the same as a babies head.
3) Thus, when Levitt tests babies for intelligence, he is bound to get similiar scores, because human infants are similarly neotenized (if they weren't they couldn't all be infants!)
Posted by: PJGoober at Mar 13, 2006 7:14:08 PM
PS.I don't profess to know all the answers, I am open to new data, but I just wanted to explain how Levitt's and the Bell Curves findings may be compatable.
Posted by: PJGoober at Mar 13, 2006 7:27:09 PM
I agree with PJGoober. The fact that a trait doesn't become evident until long after birth doesn't necessarily mean that it's a result of environmental influences rather than genetic influences. There are genes that cause a heightened risk of breast cancer, but that doesn't mean that people who are born with those genes have breast cancer at birth.
I've only read the abstract. The authors recognize the possibility that genetic differences would emerge later in life, but they seem to downplay that possibility. Has anyone read the full article? Do they present any other evidence on that point?
PC Disclaimer: I'm not saying that there are racial genetic disparities in intelligence. I'm just saying that this appears to be very weak evidence on the subject.
Posted by: FXKLM at Mar 13, 2006 7:51:50 PM
I've only read the abstract. The authors recognize the possibility that genetic differences would emerge later in life, but they seem to downplay that possibility. Has anyone read the full article? Do they present any other evidence on that point?
PC Disclaimer: I'm not saying that there are racial genetic disparities in intelligence. I'm just saying that this appears to be very weak evidence on the subject.
Maybe you should spring for the five bucks and read it yourself before criticizing it.
Posted by: Bernard Yomtov at Mar 13, 2006 8:57:32 PM
Two points, Bernard. First, this is the Internet. Criticizing things I haven't read is my god-given right. Haven't you ever been to Slashdot? :-)
Second, it's available elsewhere for free. There's a link on the Freakonomics blog. You can all find it here:
http://post.economics.harvard.edu/faculty/fryer/papers/fryer_levitt_ecls_babies.pdf
Posted by: FXKLM at Mar 14, 2006 12:30:26 AM
In Australia one would obviously expect black people to be gentically more intelligent that white people because of the heavy load of disease and parasites people had to adapt to in Europe. This would presumably lead to less selection for intelligence and more selection for disease resistance amoung whites. But as African blacks were enslaved mainly because of their disease resistance I guess it is possible that blacks in the U.S. are just as genetically unintelligent as whites.
Posted by: Ronald Brak at Mar 14, 2006 12:42:19 AM
Levitts study is a JOKE, at least how it is presented. How can you even try to measure intellegence for people who have not yet developed cognitive skills?
The argument he uses is that there is a correlation (often low, although he emphasizes the highest ones, that give 0.3) between *another* test that is similar to the baby survey Levitt uses in his paper and measured IQ at age 3-5.
The latest study he uses is for white only. It gives a correlation for Bayley MDI and IQ at age 3 of 0.14 and age 5 of 0.06. He does not present any data for the correlation of the test and actual adult IQ, and of course no figures about race.
(Remember, real g loaded IQ tests tend to have much higher correlations with each other for actual adults, up to 0.8. But they don’t give us the results we want to hear).
It is also well known that Asian children mature slower and African children somewhat faster (for example walking earlier and reaching puberty one average 1 year before whites). Surprise, Levitt finds that Asian children score lower in the test. If anything, it is reasonable that races that are genetically in need of higher IQ mature slower.
But since different races have somewhat different maturity rate, there is nothing that says this means anything. To take the extreme example of a previous commentator, an alien studying a new born chimp and a new born human might not well determine which is the smarter race. Certainly the chimp will do better in certain aspects of this test.
I used to admire Levitt, even despite the abortion paper disaster, because I figured the guy was at least intellectually honest, if wrong. The way this study is presented proofs that he has become what they accuse him of, intellectually dishonest.
The politically correct NYT crowd cannot stand the implications of ever increasing evidence for the racial IQ gap black-white-asian. So Levitt gives people with little critical thinking what they want to hear “IQ gap diminishes when we measure something that clearly is not IQ!”.
By the way guys, if you want to be a Clark winning economist AND write for the NYT and get on TV often here is another great research plan.
Height and IQ are correlated (at roughly the same low level as Levitts instrument). Why not use height as a proxy for IQ, than prove that short Asians have lower genetically IQ than tall African-Americans? That aught to shut Murray up!
Posted by: Disapointed at Mar 14, 2006 1:06:06 AM
This is a hotbed topic, but I wonder, if it si established that there is a racial bell curve, what then? I contend that culture and family life are so overwhelmingly more important that it doesn't much matter.
Posted by: Kyle N at Mar 14, 2006 6:36:20 AM
KOKO the gorilla has tested 70-95 on a human IQ test but reached that IQ level at a much lower age than an average human child. Perhaps that supports the argument that genetic IQ differences are more to do with the length of intellectual development rather than intrinsic IQ at birth?
Posted by: Stuart at Mar 14, 2006 7:45:50 AM
I have little interest in the question of whether the resident of Iraq are better off because of the war. I want to see if the US is more secure or more powerful
because of the war. The other question is not why we spend our resources on war.
Posted by: spencer at Mar 14, 2006 3:51:16 PM
Shifting topics to Google Mars: It lets you select three different views of the satelite imagery: visible light, infra-red, and elevation color-coded. I was disappointed that, unlike Google Maps, there was no option for viewing streets.
Or at the very least, canals.
[Addendum: entering "canal" in the search box does return something. Alas, searching for "little green men" or "John Carter" returned nothing.]
Posted by: eddie at Mar 14, 2006 7:40:16 PM
Koko the gorilla has an IQ between 70 and 95? I would love to see the test she took.
I thought IQ tests compared "mental age" to "actual age." At what age did she take the test? What human age was she being benchmarked against?
Or is it just that she scores within a couple of standard deviations of the mean human, or better than 5% of the human population? Really now. Again, I would love to see the test.
Gorillas fundamentally lack a number of human cognitive abilities that even really stupid people have.
I'm a little skeptical to say the least.
Posted by: Barbar at Mar 14, 2006 11:03:04 PM
Barbar writes:
[Koko the gorilla has an IQ between 70 and 95? I would love to see the test she took.]
Me too, does anyone have any information it? Googling koko, gorilla, and iq turns up many sites mentioning the 70-95 IQ figure, but few details about the test. Here is a good BBC article:
http://news.bbc.co.uk/2/hi/americas/3548246.stm
Posted by: PJGoober at Mar 14, 2006 11:28:31 PM
I just wanted to ask a question about the last China fact of the day. If only one percent of U.S. car sales are to first time buyers does that mean the average American goes through about a hundred cars in their life time?
Posted by: Ronald Brak at Mar 14, 2006 11:57:46 PM
[I thought IQ tests compared "mental age" to "actual age." ]
I think that's how IQ was originally defined (hence Quotient) for *children*. For adults that's not really meaningful, and you'd just use a raw performance score. See wikipedia. Ditto for Koko, I'd guess.
I could see giving an ape a Raven's Progressive Matrices test.
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