HBD Chick has already addressed their response from pretty much the same perspective I will, but just to make it official…
I originally complained that Galton’s Victorian sample was more elite than the modern day samples in the study, and so could be expected to have higher IQ by selection bias alone. The authors counter that Galton broke his sample down into demographic subcategories, and each of those subcategories does better than the corresponding subcategory today – therefore, demographic differences are not responsible for the IQ difference.
HBD Chick pointed out, correctly, that the similarly-named categories hide some big differences. For example, Silverman directly compares Galton’s Victorian students (presumably college students, since we’re talking age 18 – 30) to 1940s college students. While both groups are college students, one is more elite than the other: according to National Center For Education Statistics, the percent of Americans with bachelors’ degrees rose from about 2% in 1900 to about 10% in the 1940s. If England was similar, and if college is pretty meritocratic, then the 1880 student sample was drawing form about the smartest 2% of people, and the 1940s student sample from about the top 10% of people.
The other comparison the authors brought up was Anger’s 1993 sample of “220 postal, hospital and insurance workers from three different US cities”, which they compared to Galton’s Clerical/Semi-Skilled and Semi-Professional groups and found that, even matched job for job, the Victorians did a bit better. This is good work, but I am still skeptical for two reasons.
First, in a society with a large underclass, the middle-class will be comparably elite. Suppose that we took the least productive 90% of people in 2013 America and put them in those power-generating pods from the Matrix. We still need postal workers, but now the postal workers are coming from what was previously the top 10% of the population – maybe people who would have been college professors in the old system. But the Victorians had a comparably larger underclass (small farmers and factory workers) and a comparably smaller middle class than we do. Therefore, we would expect Victorians with a standard middle class occupation to be drawn from more elite segments of the population than a comparable modern with the same occupation.
Second, Galton’s sample was still self-selected from people who came to a science museum in an elite city and paid him money! I propose that the average postman you will find buying science-related merchandise in the gift-shop of the Exploratorium in San Francisco will be smarter than the average postman drawn randomly from the distribution of postmen!
So although I appreciate the authors’ time and politeness in responding to me, I am still skeptical of their findings.
Let me move to one other point that many of my commenters protested. In the original article, I said:
All the theory here sort of checks out, except for the part where they say IQ changed 15 points in a hundred years, which is just a little bit faster than any responsible person expects evolution to progress. People critique the idea that Ashkenazi Jews could have shifted fifteen points in nine hundred years on the grounds that it’s too fast.
Many people correctly noted that it’s a lot harder to evolve a complex feature in the first place than it is to break one, and therefore my comparison was invalid. I actually considered this when writing the original post, but decided to leave it in. Here’s why.
In a normally distributed trait like IQ, over a short period like nine hundred years most of the action isn’t going to come from de novo mutations. It’s going to come from people on one side of the bell curve out-reproducing their peers on the other. This can happen just as quickly for smartening up as it can for dumbing down.
A commenter writes:
The sheer 15 point drop made me go ‘nope’ right away. If I remember Lynn right we should be losing about one IQ point per generation of our genetic potential in the West, two thirds of that due to mass immigration which wasn’t a big factor for Britain before the late 70s. The dysgenic drop can’t be more than about 3 points.
These seem like much more reasonable numbers. They also seem like a good reason not to worry about dysgenics ever again. How many more centuries do we have in which natural selection is going to be the main force shaping our genome, as opposed to genetic engineering or transfer to nonbiological life? Maybe one, if you’re really pessimistic? Losing three IQ points before that time (most of which are probably instantly regained via Flynn Effect or some kind of low-budget intelligence amplification like the racetams) isn’t anything to lose much sleep over.