I personally find those results really dubious. How accurate were the measurements from the mid 19th century? And even then, the leverage on those scatter plots

I personally find those results really dubious. How accurate were the measurements from the mid 19th century? And even then, the leverage on those scatter plots is huge. (eg: http://cs.wellesley.edu/~cs199/lectures/one-outlier.png http://cs.wellesley.edu/~cs199/lectures/one-outlier.png) Additionally, because of a lack of a data, they used means instead of medians on highly skewed data. A few individuals could have a much larger effect on results this way. Finally, just because we measure good correlations between IQ and RT in modern times doesn't justify extrapolating these conclusions to the 19th century. P.S. I find this a little dubious "The Victorian era was characterized by great accomplishments. As great accomplishment is generally a product of high intelligence. . ." Sure the 19th century had better innovation than came before, but so did the 20th and 21st century. This doesn't have much impact on the findings, but it still bugs me.