It's not been established that there is a trend to spot.
Here's a recent and fairly pro-eugenics survey of all the results they could find showing a reduction in IQ:
And even they basically are only at the stage of saying "maybe there's a hidden trend, that's obscured by other trends moving in the opposite direction" (they think society becoming more abstract has caused a false rise in IQ, due to IQ tests measuring that socially taught facility with abstraction rather than raw intelligence, this may have disguised an actual drop in intelligence).
So maybe it does help to have a preconcieved cause to spot this hypothesised trend.
Regarding their hypothesis, it's kind of a philosophical question about whether you'd rather have a society full of uneducated bumpkins (not sure there is an english word for someone with raw intelligence but no education) with sharper reflex times or ability to discern colors, than a modern post-graduate who scores slightly worse on those tests but better on IQ. It's also somewhat unlikely that the former is going to be having less children than the latter, so they whole dysgenic thing seems to be on shakey ground.
Sure. Here's a short collection:
- "Sexual Selection as a Justification for Sex" http://www.unz.com/gnxp/sexual-selection-as-a-justification-...
- "Holocene selection for variants associated with cognitive ability: Comparing ancient and modern genomes" http://biorxiv.org/content/early/2017/02/20/109678 , Woodley et al 2017
- "Rates and Fitness Consequences of New Mutations in Humans" http://www.genetics.org/content/190/2/295.full , Keightley 2012
- "Parent-of-origin-specific signatures of de novo mutations" https://www.gwern.net/docs/genetics/2016-goldmann.pdf , Goldmann et al 2016
- "Older fathers' children have lower evolutionary fitness across four centuries and in four populations" http://biorxiv.org/content/early/2016/03/08/042788 , Arslan et al 2016 (from "The cost of inbreeding in terms of health" http://www.unz.com/gnxp/the-cost-of-inbreeding-in-terms-of-h... )
- "Childhood Autism and Assortative Mating" http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.422... , Golden 2013
- "Heritability, Autism, & Fear of Breeding" http://www.unz.com/gnxp/heritability-autism-fear-of-breeding...
- "Estimating the Inbreeding Depression on Cognitive Behavior: A Population Based Study of Child Cohort" http://www.plosone.org/article/info:doi/10.1371/journal.pone... ; see also "Genetic diversity and intellectual disability" http://blogs.discovermagazine.com/gnxp/2013/07/genetic-diver...
- "Mutation and Human Exceptionalism: Our Future Genetic Load" http://www.genetics.org/content/202/3/869 , Lynch 2016
- "The Biodemography of Fertility: A Review and Future Research Frontiers" https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4577548/ , Mills & Tropf 2015
- Fertility and intelligence https://en.wikipedia.org/wiki/Fertility_and_intelligence
- "Genetic evidence for natural selection in humans in the contemporary United States" http://biorxiv.org/content/early/2016/05/05/037929 , Beauchamp 2016
- "Assortative mating and differential fertility by phenotype and genotype across the 20th century" http://www.pnas.org/content/early/2016/05/25/1523592113.full , Conley et al 2016a (Dysgenics found in the USA, 1920-1955. Appendix http://www.pnas.org/content/suppl/2016/05/25/1523592113.DCSu... ); see also "Changing Polygenic Penetrance on Phenotypes in the 20th Century Among Adults in the US Population" http://www.nature.com/articles/srep30348 , Conley et al 2016b
- in Iceland: decrease in the education polygenic score 1910-1990, "Selection against variants in the genome associated with educational attainment" https://www.gwern.net/docs/genetics/2017-kong.pdf , Kong et al 2017 (graph https://www.gwern.net/images/genetics/2017-kong-iceland-educ... ; media https://www.theguardian.com/science/2017/jan/16/natural-sele... "Natural selection making 'education genes' rarer, says Icelandic study: Researchers say that while the effect corresponds to a small drop in IQ per decade, over centuries the impact could be profound" )
- in the US: decrease in the education polygenic score 1920-1960, "Mortality Selection in a Genetic Sample and Implications for Association Studies" http://biorxiv.org/content/early/2016/04/21/049635 , Domingue et al 2016 (graph https://www.gwern.net/images/genetics/2016-domingue-usa-educ... )
- "Genome-wide analysis identifies 12 loci influencing human reproductive behavior" https://www.gwern.net/docs/genetics/correlation/2016-barban.... , Barban et al 2016 (supplement http://www.nature.com/ng/journal/v48/n12/extref/ng.3698-S2.x... ; genetic correlations with fewer later offspring: _r~g~_ = -0.236 and 0.712 respectively. Cross-sectional confirmation of Conley et al 2016. )
- "How cognitive genetic factors influence fertility outcomes: A mediational SEM analysis" http://biorxiv.org/content/early/2016/08/18/070128 , Woodley et al 2016
- "The negative Flynn Effect: A systematic literature review" https://www.gwern.net/docs/iq/2016-dutton.pdf , Dutton et al 2016
- "Assortative Mating, Class, and Caste" https://www.gwern.net/docs/genetics/2015-harpending.pdf , Harpending & Cochran 2015
Secular declines in cognitive test scores: A reversal of the Flynn Effect: https://www.gwern.net/docs/iq/2016-dutton.pdf