Did the Victorians have faster reactions?

>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.

It's not terribly convincing just by itself. He's done newer work showing that other proxies for IQ like vocabulary have also decreased over time: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4404736/ And math SAT scores have dropped over time: https://brainsize.wordpress.com/tag/michael-a-woodley/ But we are only just starting to be able to test for genes that correlate with intelligence to see if they have decreased over time.

I haven't read the paper linked, Woodley-teNijenhuis-Murphy, but do they address this?

Crucially, the heritability of IQ seems to be only increasing the more we learn about it. Older studies showed it to 'only' be around 60% with more modern research indicating it is upwards of 80%. [2] One peculiar, and confounding effect, here is how IQ behaves on youth. In young age environmental conditions can play a more substantial role in IQ, yet as youth approach adolescence and beyond their IQ tends to approach their 'genetic expectation.'

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And all the above assumes something many do not seem aware of (based on a different thread). IQs in the developed world seem to have started to substantially decline with no viable convenient explanation. Environmental or educational conditions achieving diminishing returns are what we would like to believe, yet of course if that was the case we'd expect to see an asymptotic decline of growth approaching 0. Instead we are seeing an actual decline in IQ. [3] One conflicting bit here is that most evidence indicates this decline started happening sometime in the mid 90s. Prior to that IQs had been increasingly, though more slowly over time - but that decline of growth is to be expected.

[1a] - https://www.statista.com/statistics/241530/birth-rate-by-fam...

[1b] - https://www.census.gov/topics/health/fertility.html (the statista graph presents this data in a cleaner format - adding this as just a more reliable source than random internet site)

[2] - https://en.wikipedia.org/wiki/Heritability_of_IQ

[3] - https://en.wikipedia.org/wiki/Flynn_effect#Possible_end_of_p...

Maybe what's happening is that IQ has been declining for a longer time, but the gains in health and nutrition were offsetting the effect. An interesting variable to compare to is life expectancy, which is a proxy for health. Its growth in western countries has been slowing and in the US it has even started declining. Studies have shown a link between IQ and life expectancy. Those studies generally looked towards a reason why higher IQ would lead to higher life expectancy, but perhaps the causation is reverse.

https://thinkprogress.org/exclusive-elevated-co2-levels-dire...