The authors clearly did not believe that the well-attested differences in IQ testing across ethnic groups could be ascribed to genetic factors.
I think that there’s not definitive evidence on the subject, even today. The definitive evidence would be if we knew the specifics of the causal link between genetics and IQ and had representative genetic samples from different racial groups, so we could look at the prevalence of various IQ genes and calculate what we’d estimate the average racial IQ to be for various groups from their genes. That’d give us an estimate of the genetic factors, and the difference between that and measured IQ would give us an estimate of the environmental factors.
My read of the field, though, is that the majority of the evidence points to the majority of the difference between racial groups being explained by genetic factors, and the trend has been that the hereditarian position has been growing more solid over time, especially as more and more people have been sequenced.
For example, African Americans represent a significant observational data source on ancestry and intelligence, since while the average African American has 80% African ancestry, that percentage can vary significantly from person to person. Intelligence: Knowns and Unknowns reports that a study that used blood groups to determine ancestry failed to find a correlation between European ancestry and IQ; more recent research claims to have found a correlation between European ancestry and IQ and controlled for the impact of skin color.
You’re welcome!
I think that there’s not definitive evidence on the subject, even today. The definitive evidence would be if we knew the specifics of the causal link between genetics and IQ and had representative genetic samples from different racial groups, so we could look at the prevalence of various IQ genes and calculate what we’d estimate the average racial IQ to be for various groups from their genes. That’d give us an estimate of the genetic factors, and the difference between that and measured IQ would give us an estimate of the environmental factors.
My read of the field, though, is that the majority of the evidence points to the majority of the difference between racial groups being explained by genetic factors, and the trend has been that the hereditarian position has been growing more solid over time, especially as more and more people have been sequenced.
For example, African Americans represent a significant observational data source on ancestry and intelligence, since while the average African American has 80% African ancestry, that percentage can vary significantly from person to person. Intelligence: Knowns and Unknowns reports that a study that used blood groups to determine ancestry failed to find a correlation between European ancestry and IQ; more recent research claims to have found a correlation between European ancestry and IQ and controlled for the impact of skin color.