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A deep dive into poverty in the US of A


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3/3(For anyone who skipped to the last page, if one is going to read this post, read my two previous posts on the previous page first)

Finally, the video.



Dombrowski in the video mentions how the US Army used to use an IQ test for recruitment.


This is true, that test was the SAT. However, he fails to mention that the US Army still uses an IQ test in the recruitment process, the ASVAB, which has ~.8 correlation with IQ. This is misleading as he basically implied that this was an old, discredited practice, when that is not the case. 




He mentions the practice of IQ being linked to race in the past


This is true, but it is an anachronistic criticism. The modern view is that races aren’t unique subspecies. Therefore, genetic variants which are associated with higher intelligence are present within all “races”, but the genetic variants simply exist in different frequencies within these so-called “races.”



He mentions how there are environmental impacts on IQ


This is already acknowledged by psychometricians, as I pointed out in my starting paragraph in post 1/3, however, he is once again misleading the audience in this video and not giving the complete picture in a few ways:


 1)  He mentions how observed average population IQ was increasing in the 20th century, this is known as the Flynn Effect.


However, he doesn’t mention the existence of the Reverse-Flynn Effect- the observation of declining average population IQ. This is misleading because it doesn’t give the audience the knowledge that the average population IQ can also go down; it doesn’t just go up infinitely because of “improvements in environment”.  In fact, one study suggests that the Western world has seen a decline in average IQ of 13.35 points since the Victorian Era. To put that in perspective, 15 IQ points is an entire standard deviation downward along the normal distribution of IQ!


There isn’t any data that the Flynn effect has continued and that it has continued to the same degree as post WWII. Many of the environmental improvements post WWII in the US/West were likely do to the normalization of the economy in that part of the world (the Great Depression came to an end and the WWII era economic hardships were over), along with likely improvements in water/electricity/sanitation access.


These same improvements aren’t likely repeatable in modern Western countries where these basic needs are met even among the poorest. However, as shown earlier, even research on education shows that improvements can reach an asymptote. If one were solely discussing underdeveloped countries, like India or some of those in sub-Saharan Africa, then I could see these types of large environmental changes possibly having large effects, but in the modern Western world, it seems like wishful thinking more than anything. 


(The below paper just lets the reader know that the Reverse-Flynn Effect exists, and it hypothesizes what could be causing it. It is not necessary to read for understanding this post, but it could be interesting)


Acosta et al (2019)

https://scholarworks.utep.edu/cgi/viewcontent.cgi?article=2339&context=cs_techrep#:~:text=Reverse Flynn effect.,grow%3B instead%2C they decline.  


(This next paper is the source for detailing the decline in Western population IQ since the Victorian era)

Woodley et al(2013)



The Victorian era was marked by an explosion of innovation and genius, per capita rates of which appear to have declined subsequently. The presence of dysgenic fertility for IQ amongst Western nations, starting in the 19th century, suggests that these trends might be related to declining IQ. This is because high-IQ people are more productive and more creative. We tested the hypothesis that the Victorians were cleverer than modern populations, using high-quality instruments, namely measures of simple visual reaction time in a meta-analytic study. Simple reaction time measures correlate substantially with measures of general intelligence (g) and are considered elementary measures of cognition. In this study we used the data on the secular slowing of simple reaction time described in a meta-analysis of 14 age-matched studies from Western countries conducted between 1889 and 2004 to estimate the decline in g that may have resulted from the presence of dysgenic fertility. Using psychometric meta-analysis we computed the true correlation between simple reaction time and g, yielding a decline of − 1.16 IQ points per decade or − 13.35 IQ points since Victorian times. These findings strongly indicate that with respect to g the Victorians were substantially cleverer than modern Western populations.


2) He implies that the entire Flynn effect was due to environmental changes.


That is not necessarily true. In Evolutionary Biology there is a mating pattern called Assortative Mating. It is a form of sexual selection in species where individuals of similar pheno-/genotypes reproduce with each other at a greater rate than one would expect if mating happened randomly.


This effect exists in humans as well. If one looks at this paper below, they will see that humans commonly do assortative mating on the basis of education: people with similar education levels prefer to marry/reproduce with each other.


Schwartz et al (2003)



Due to the fact that we know intelligence is correlated with lifetime education, and we know that intelligence is significantly heritable, we know that it is likely that people who are assortative mating on the basis of education are also doing so on the basis of intelligence by extension. This would lead to the conclusion that both the Flynn and Reverse Flynn effects can be influenced by this reproductive pattern. There is indeed a case for a genetic contribution to both the Flynn Effect and the Reverse Flynn Effect.



Edited by Tibarn
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