Prompted by my post Ta-Nehisi Coates reached out to Neil Risch for clarification on the nature (or lack thereof) of human races. All for the good. The interview is wide ranging, and I recommend you check it out. Read the comments too! Very enlightening (take that however you want).
When it comes to this debate I have focused on the issue of population substructure, or race. The reason is simple. Due to Lewontin’s Fallacy it is widely understood among the “well informed general public” that “biology has disproved race.” Actually, this is a disputable assertion. For a non-crank evolutionary biologist who is willing to defend the race concept for humans, see Jerry Coyne. When you move away from the term “race,” then you obtain even more support from biologists for the proposition that population structure matters. For example, a paper in PLoS GENETICS which came out last week: Analysis of the Genetic Basis of Disease in the Context of Worldwide Human Relationships and Migration. In other words, it is useful to understand the genetic relationships of populations, and individual population identity, because traits correlate with population history. Barring total omniscience population history will always probably matter to some extent, because population history influences suites of traits. If nothing in evolutionary biology makes sense except in light of phylogeny, much of human biology is illuminated by phylogeny.
But that doesn’t speak to the real third rail, intelligence. Very few people are offended by the idea of the correlation between lactase persistence and particular populations. Neil Risch says in the interview with Coates:
Update: First, people coming to this weblog for the first time should know that I moderate comments. So if you leave an obnoxious one it’s basically like an email to me (no one will see it). Second, the correlation between height and intelligence is not that high. This association is probably not going to be intuitively visible to anyone, but rather only shows up in large data sets. So please stop offering yourself as a counter-example of the trend (also, the key is to look within families, because the signal here is going to be swamped by other factors when you compare across populations). Third, a friend has sent me another paper which does confirm that even within sibling cohorts there does seem to be a correlation between height and I.Q. The problem is that it is a very small one, so you need large data sets with a lot of power to see it.
One moderately interesting social science finding is that there is a positive correlation between height and measured intelligence (e.g., on an I.Q. test). Setting aside the possibility that I.Q. tests designs are culturally biased against shorter people, one wonders why this is so. Height is a highly heritable trait where most of the variation within the population is due to variation as numerous genes. In other words, there isn’t a “tall” or “short” gene, but thousands and thousands of variants which shape the variation of the trait across the population. When I say it is highly heritable, I mean to imply that most of the variation in height in developed societies is due to genes (80-90%). As it happens intelligence is somewhat similar in its genetic architecture, heritable due to small effects across many genes. In general estimates for the heritability of intelligence tend to be somewhat lower, on the order of ~50% rather than 80-90%.
It is due to the highly polygenic nature that both of these traits have been posited as candidates for a “good genes” model of sexual selection. Presumably individuals with a higher mutational load will have lower intelligence and be shorter, all things equal, because these traits have extensive genome-wide coverage and are big targets. Geoffrey Miller’s The Mating Mind: How Sexual Choice Shaped the Evolution of Human Nature, was predicated on this logic. If the mutational load argument holds then the reduced I.Q. of shorter individuals may simply be due to the same cause: “bad genes.”
A few years ago I put up a post, WORDSUM & IQ & the correlation, as a “reference” post. Basically if anyone objected to using WORDSUM, a variable in the General Social Survey, then I would point to that post and observe that the correlation between WORDSUM and general intelligence is 0.71. That makes sense, since WORDSUM is a vocabulary test, and verbal fluency is well correlated with intelligence.
But I realized over the years I’ve posted many posts using the GSS and WORDSUM, but never explicitly laid out the distribution of WORDSUM scores, which range from 0 (0 out of 10) to 10 (10 out of 10). I’ve used categories like “stupid, interval 0-4,” but often only mentioned the percentiles in the comments after prompting from a reader. This post is to fix that problem forever, and will serve as a reference for the future.
First, please keep in mind that I limited the sample to the year 2000 and later. The N is ~7,000, but far lower for some of variables crossed. Therefore, I invite you to replicate my results. After the charts I will list all the variables, so if you care you should be able to replicate displaying all the sample sizes in ~10 minutes. I am also going to attach a csv file with the raw table data. As for the charts, they are simple.
- The x-axis is a WORDSUM category, ranging from 0 to 10
- The y-axis is the percent of a given demographic class who received that score. I’ve labelled some of them where the chart doesn’t get too busy
All of the charts have a line which represents the total population in the sample (“All”).
In light of my previous posts on GRE scores and educational interests (by the way, Education Realist points out that the low GRE verbal scores are only marginally affected by international students) I was amused to see this write-up at LiveScience, Low IQ & Conservative Beliefs Linked to Prejudice. Naturally over at Jezebel there is a respectful treatment of this research. This is rather like the fact that people who would otherwise be skeptical of the predictive power of I.Q. tests become convinced of their precision of measurement when it comes to assessing whether a criminal facing the death penalty is mentally retarded or not! (also see this thread over at DailyKos). You can see some of the conservative response too.
The post below on teachers elicited some strange responses. Its ultimate aim was to show that teachers are not as dull as the average education major may imply to you. Instead many people were highly offended at the idea that physical education teachers may not be the sharpest tools in the shed due to their weak standardized test scores. On average. It turns out that the idea of average, and the reality of variation, is so novel that unless you elaborate in exquisite detail all the common sense qualifications, people feel the need to emphasize exceptions to the rule. For example, over at Fark:
Apparently what had happened was this: He played college football. He majored in math, minored in education. When he went to go get a job, he took it as a math teacher. When the football coach retired/quit, he took over. When funding for an advance computer class was offered, he said he could teach it after he got the certs – he easily got them within a month.
So the anecdote here is a math teacher who also coached. Obviously the primary issue happens to be physical education teachers who become math teachers! (it happened to me, and it happened to other readers apparently) In the course of double checking the previous post I found some more interesting GRE numbers. You remember the post where I analyzed and reported on GRE scores by intended graduate school concentration? It was a very popular post (for example, philosophy departments like it because it highlights that people who want to study philosophy have very strong GRE scores).
As it happens the table which I reported on is relatively coarse. ETS has a much more fine-grained set of results. Want to know how aspiring geneticists stack up against aspiring ecologists? Look no further! There are a lot of disciplines. I wanted to focus on the ones of interest to me, and I limited them to cases where the N was 100 or greater (though many of these have N’s in the thousands).
Likely presidential candidate Rick Perry’s college transcript at Texas A & AM has been published. Here are the highlights:
…In his freshman and sophomore year, Perry struggled with core science classes, earning D’s in several organic chemistry classes and C’s in general chemistry and physics.
But after Perry switched his major at the beginning of his fall semester in 1970, his grades didn’t improve. Perry got a C in Reproduction in Farm Animals, a C in genetics, a D in Feeds & Feeding, a C in Sheep & Angora Goat Production and two C’s in animal breeding classes.
Many of Perry’s other classes involved military education. Perry has previously credited his time in the A&M Corps of Cadets with giving him the necessary discipline to complete school.
Perry got two C’s in Development of Air Power and took four levels of World Military Systems, earning two C’s, a B and an A. The A was one of only two Perry earned at college — the other was for a class called Improv. of Learning.
The future governor only took one political science class while he was in school — American National Government, for which he earned a B. Other classes outside of Perry’s major included Shakespeare and Writing for Professional Men, which earned him two D’s.
Perry took two summer sessions before his senior year but still needed two more after the rest of his class graduated to complete a degree. He graduated in August of 1972.
Long time reader Ian comments:
A comparison with “the American public” isn’t really appropriate – to even be in the pool where you’re thinking about an academic career, you need to have a college degree. And that population if memory serves, is far more liberal than the population at large. More realistic would be a comparison with the population of people who have graduate degree….
Roughly about ~20% of Americans self-identify as “liberal,” and ~40% as conservative. The General Social Survey has a variable POLVIEWS, which asks individuals to assign themselves to a position on a political spectrum, from “extremely liberal” to “extremely conservative,” like so:
1 = Extremely liberal
2 = Liberal
3 = Slightly liberal
4 = Moderate
5 = Slightly conservative
6 = Conservative
7 = Extremely conservative
So in other words, the higher the integer, the more conservative the individual. The GSS has a variable, EDUCATION, which records the highest level attained. It falls into three classes, high school, bachelor’s, and graduate degrees (I assume those who did not complete high school are omitted because they didn’t attain an education?). Additionally, it has a 10 word vocabulary test, WORDSUM, which has a 0.71 correlation with general intelligence. I combined those on the interval 0-4 (they got 0 to 4 answers correct on the test), and labeled them “dull.” 5-8 I labelled “average. And finally, 9 and 10 I labeled smart (about 20% are dull, 65% average, and 15% smart, in the total data set). Constraining the sample to the year 2000 and later, I produced the following charts:
Ms. Palin, in fact, draws almost as much search traffic worldwide as the man she would face if she wins the Republican nomination: Barack Obama. And her name is searched for about 30 percent more often than the President’s among Google users in the United States.
Some members of Ms. Palin’s family also draw as much attention has the other Presidential contenders. Todd Palin, her husband, gets about as much search traffic as Mr. Pawlenty. Bristol Palin, her daughter (and a finalist on “Dancing With the Stars”), gets several times more than any of them (as does her former boyfriend, Levi Johnston).
I thought of this News IQ Quiz from Pew. I got 12 out of 12, which apparently places me in the top 1% of quiz takers? The only question I hesitated on was #11 for what it’s worth. Check out how different demographics do in the aggregate and by question: