It may occur both through internal factors (such as the more intelligent in a population having lower fertility) and/or external factors (such as race mixing with another population with lower intelligence).
A large number of studies on average IQ have stated declining average genotypic IQ in developed countries. Until recently, this has been argued to be concealed regarding average phenotypic (measured) IQ by the environmentally caused Flynn effect. Recent studies and literature reviews have instead stated declining average phenotypic (measured) IQ in several developed countries with, for example, a study on France stating that measured average IQ declined by 3.8 points during the 1999–2008/9 time period.
Several IQ researchers have expressed very pessimistic views regarding the future of Western civilization due to dysgenic trends.
Dysgenic effects in early societies
Dysgenic processes have been argued to be an important cause of the decline and fall of many advanced historical civilizations, such as of ancient Greece and ancient Rome.
The decline of Muslim, or more narrowly Arab societies, after the initial large achievements, has been argued to have possible dysgenic causes. An extensive interbreeding with females slaves from sub-Saharan Africa is argued to have occurred. It has been argued that Middle Easterners and North Africans are now darker than they used to be earlier. Another explanation is widespread use of contraception, especially by those with higher IQ, in contrast to Europe, where the Catholic church for a long time successfully condemned contraception. Still another explanation is that the rote memorization, simple dogmatism, and absence of abstract principles and analysis argued to have characterized Muslim education and religion would have not favored those with high intelligence. There may also have been relatively less need for high intelligence after the successful conquests were completed. Yet another explanation is that many of the early achievements of Muslim societies were actually accomplished by non-Muslims.
The prohibition of polygamy by the Catholic church has been argued to have caused a dysgenic effect by making it easier for less achieving men to find wives. However, it has also been argued that polygamy in other societies caused the importing of female slaves from low IQ groups and dysgenic race mixing. The decision to require celibacy of priests has been argued to be dysgenic, since men with the degree of intelligence needed to become priests were at least in theory forced to be childless. On the other hand, the Catholic church banned contraception, which on average is used more effectively by the intelligent.
Dysgenic effects in modern societies
During the mid-nineteenth century, several scientists, including Charles Darwin, began to worry about and find empirical evidence for that the genetic quality of Western nations was deteriorating. The earlier natural selection had changed, such as by improved public health and reduced infant and childhood mortality, meaning that more of the less achieving members of society reproduced successfully. Furthermore, the most able members of society tended to have few children. One proposed cause for this was marrying late, due to the demands of a career. Another explanation was that many successful men married wealthy heiresses, who become heiresses by coming from families with genetically low fertility, as shown by having no male children who could inherit. A more plausible and general explanation may be the more efficient use of contraception by the successful, due to factors such as higher intelligence and more restraint, farsightedness and the capacity to delay gratification. Such arguments and supporting research became increasingly widespread and contributed to the rise of the eugenics movement.
After World War II, research and public discussion on dysgenics and eugenics increasingly became rejected and taboo subjects. Another trend after WWII is the mass immigration to Western countries of people from races with different genetics and often an argued lower average genetic intelligence.
It has also been argued that mass killings and class warfare, such as during the French Revolution and during Communist rule, had a dysgenic effect through the killing of the more intelligent by the less intelligent. Another argument is that modern warfare may have had a dysgenic effect, due to the healthy selectively being drafted and killed, while preserving the unfit at home. However, such effects would be limited to particular regions during particular periods.
The concern has mainly been regarding three areas: deteriorating genetic health, deteriorating genetic personality ("moral character"), and deteriorating genetic intelligence.
Improved medical and social care may possibly lead to increased incidences of genetic disorders and genetically influenced disorders. Practices such as genetic counseling and prenatal screening may possibly counteract this effect, for the disorders for which this is done.
It has been estimated that over the next 30 years in developed countries, there will be a 26 percent increase in hemophilia and a 120 percent increase in cystic fibrosis.
Those worried about dysgenics have considered traits such as self-discipline, work motivation, energy, ambition, and strong moral sense, that are argued to contribute greatly to a person's achievements, but in modern populations are argued to contribute less to reproductive success than previously. A modern term for many of these traits is conscientiousness.
Conscientiousness has a high heritability.
Richard Lynn in a 1995 study of a sample of British criminal convicts found that they had an average fertility of 3.91 children. The general population had an average fertility of 2.1.
Construct for the Social Sciences
Examples of studies finding declining average IQ
Many studies have stated declining average genotypic IQ due to dysgenic effects. Some examples of such studies are mentioned in this and the following sections. Recent studies have also found declining average phenotypic IQ. These studies are discussed in the section "The Flynn Effect".
A 2010 study stated that in the absence of migration and with constant environment, genetic selection would reduce the average IQ of the US population by about 0.8 points per generation. Although such a number may seem small, over time this adds up to a substantial effect since the start of the dysgenic trends.
Richard Lynn has predicted that, given the mix of low-IQ people coming to the United States, there will be a 4.4 point decline in average IQ between 2000 and 2050. He expects gentler declines in Canada and New Zealand because they receive relatively more high-IQ Chinese immigrants. Between 2000 and 2050, there should be a world-wide decline of 1.29 IQ points per generation.
A 2013 study found that the average reaction in time in Western countries had declined greatly during the 1889-2004 time period. The decline was equivalent to − 1.16 IQ points per decade or − 13.35 IQ since Victorian times. Reaction time is an indirect measure of IQ and in particular of genotypic IQ.
Later studies criticizing this have made arguments such as methodological problems making it impossible to make comparisons, or that there has been a decline, but that it is impossible to tell how large.
A 2015 study examining the degree of craniofacial asymmetry for Whites in the US during the past 150 years found increasing asymmetry. This was argued to indicate increasing instability during development, with this being harmful to IQ, and possibly related to several different factors (see the section "Causes: Other explanations).
A 2016 study using genetic markers stated declining average genotypic IQ and stated that "based on these results, polygenic selection might be reducing heritable G globally by −0.253 points per decade".
Due to the shape of normal distributions ("bell curve" distributions), such as IQ, a change regarding the average value would be disproportionately larger at the extreme IQs. A decline in average psychometric intelligence of only a few points will mean a much smaller population of gifted individuals. See the Smart fraction article.
Causes: Dysgenic fertility
A large number of studies, particularly in the United States, have found that higher intelligence is associated with lower fertility. One example is a 2010 study finding that IQ in the US was negatively related to the number of children, with age-controlled correlations of −.156, −.069, −.235 and −.028 for White females, White males, Black females and Black males. "This effect is related mainly to the g-factor. It is mediated in part by education and income, and to a lesser extent by the more "liberal" gender attitudes of more intelligent people."
One explanation for the relationship between high IQ and low fertility is that higher income is associated with higher IQ. It is well-known that a country's fertility declines as the average income rises. This is sometimes referred to as the demographic transition. It has been argued to be due to a variety of causes. However, several of the studies mentioned above have examined this and have found that higher income do is an explanation, but that IQ also has an effect independent of this. Similarly, studies have also controlled for education and other possible confounding factors.
A large proportion of children are unplanned, which is related to IQ. A review stated that "Part of the problem is that those of low educational level are less likely to use contraception. Yet even among a sample of women using the same highly-effective methods, those with lower IQs were found to have much higher failure rates. Percentages having unwanted births during a three-year interval were 3%, 8% and 11% for high, medium and low IQ women, respectively. For those not using one of these methods, the percentages were 15%, 23 and 31% (Udry, 1978). After an unwanted pregnancy has occurred, higher IQ couples are more likely to obtain abortions (Cohen, 1978). Unmarried teenage girls who become pregnant are more likely to carry and deliver a baby than to have an abortion if they are doing poorly in school (Olson, 1980). Thus, each factor–from initially employing some form of contraception, to successful implementation of the method, to termination of an accidental pregnancy when it occurs–involves selection against intelligence. [...] 18% of American women said they desire more children than they expect to have. Highly educated women were more likely to fall into the “deficit fertility” category."
Other studies have demonstrated the relationship between high IQ and low fertility in other developed countries.
A 2016 study on China stated that the estimated IQ decline owing to dysgenic fertility came out to 0.31 points per decade between 1986 and 2000. The total loss from 1971 to 2000 due to dysgenic fertility was estimated to be 0.75 points. A 2017 study found dysgenic effects on IQ also in Taiwan, with the effect being stronger for younger adults.
A 2005 study of the Afro-Caribbean population of the Caribbean country Dominica found a weak dysgenic relationship.
One objection is that such differences in fertility would not result in a progressive decline in IQ, but only a somewhat lower average population IQ, after which a new steady-state equilibrium is argued to be established. However, this has been argued to depend on assumptions which are unlikely to be true, being contrary to basic evolutionary principles, and being contrary to the results from centuries of selective breeding.
A 2009 study argued that for many countries, the effect of fertility on genotypic IQ is currently overshadowed by much larger effects, due to selective mass migration of groups with varying average IQs.
Causes: Other explanations
Other explanations include increasing accumulation across generations of mutations harmful to IQ and which are no longer removed by mechanisms such as high child mortality. Increasing age of fathers may increase the prevalence of mutations harmful to IQ in sperm. Another possibility is increasing prevalence of environmental pollutants, which could be harmful to IQ and in particular during childhood as the brain develops.
The Flynn effect
Such dysgenic declines may seem contrary to the Flynn effect, which refers to the (earlier) observed increase in IQ scores over time. However, Flynn effect refers to an (earlier) increase in measured (phenotypic) IQ and not genetic (genotypic) IQ. The Flynn effect has been attributed to environmental factors, such as improved nutrition or simply improved test taking skills. It is argued that the relatively slow dysgenic decline in genotypic IQ has (earlier) been hidden by the gains, or apparent gains, from such environmental factors.
From the mid-1970s, there has been somewhat conflicting evidence on whether the Flynn effect have been continuing or whether it have gone into reverse in developed countries. Continued increases have been reported in studies the United States and some studies in Britain. Contrary to these results, studies finding that IQs have declined in recent decades have been reported in Norway, Denmark, Australia, the Netherlands, Sweden, Finland, France, and some studies in Britain. Various explanations for this has been proposed, including dysgenic fertility and immigration by lower average IQ groups. This latter conclusion has been argued to be supported by a study in Denmark, which found that the IQ of non-European immigrants military conscripts testing was 86.3, relative to 100 for indigenous Danes. French measured average IQ declined by 3.8 points during the 1999–2008/9 period, with this primarily argued to have genetic causes.
A 2016 literature review stated that "In this study, we present a systematic literature review, conducted in order to discover in precisely how many countries this reverse phenomenon has been uncovered. Using strict criteria regarding quality of the sample and the study, we found nine studies reporting negative Flynn Effects in seven countries."
A 2017 study stated that average IQ levels were falling in Scandinavian countries. The IQ of Norwegians had been increasing since 1950 until a turning point around 1995. An annual reduction of IQ by 0.21 percent on average has been measured in Norwegians since that year, equivalent to a 6.5 percent decrease between generations. Losses in Nordic nations after 1995 averaged at 6.85 IQ points, when projected over thirty years. The situation in other countries varied. Some developed countries showed increasing scores. Generally, the study argued that the largest IQ losses may be at high IQ levels, but may be accompanied by lower losses or even increases at low IQ levels.
See Race and intelligence: The genetics or not debate: The Flynn effect regarding possible causes of the Flynn effect, relation to the g factor, and argued implications for racial IQ differences.
Declining innovation rates
The peak of the per person numbers of significant innovations in science and technology and the peak of the per person numbers of scientific geniuses have been argued to have been clearly situated in the Victorian era, after which there has been a decline. A 2012 study argued that "This finding indicates that the Flynn effect, whilst associated with developmental indicators and wealth, only minimally influences innovation rates, which appear instead to be most strongly promoted or inhibited by changes in genotypic intelligence."
Pessimism regarding the future of Western civilization
Lynn in 2007 stated that he was pessimistic regarding the future of Western societies, in particular due to the dysgenic effects of the large scale mass immigration to Western countries. Before the end of 21th century White populations will become minorities in their own countries, if current trends continue. "Yet this huge demographic catastrophe has been barely noticed by the media, and anyone who mentions it is considered as a "far right racist"." He even went as far as stating that "I believe the best hope for the future of civilization lies with the Chinese and Japanese. They have not been infected with the virus of Political Correctness, and they are not admitting large numbers of immigrants. They have low fertility but this is not too much of a problem for the present and can probably be corrected in the future by paying people to have children. These are highly intelligent peoples and will probably carry the torch of civilization when it is extinguished in the United States, Canada, and Europe."
The IQ researcher Helmuth Nyborg wrote in 2012 that "The bleak situation is characteristic of the rest of Europe too, perhaps with Eastern Europe as an exception. [...] Ethnic Europeans will soon be wiped out of their own countries by this ever-expanding colossal demographic transition. Their national average IQs go down in the process, and when an average national IQ of 90 is reached, down go also their democracies and welfare. This also happens to European-Americans in the US. [...] To sum up, not only Denmark but Europe and the US get dumber by internal dysgenic decay and by northbound mass-immigration. This will have catastrophic consequences for Western democracy and welfare, but non-Western countries will also suffer. Unfortunately, most ruling (left- or right-oriented) Western leaders are not only seriously misguided by the illusion of equality but also blatantly ignorant of biological realities, so they can’t see the elephant in the room. They eventually will, but that will be beyond the point of no return."
- Dysgenics: Genetic Deterioration in Modern Populations, 1st edition - by Richard Lynnn. Complete book available online or for download.
- First chapter of Dysgenics: Genetic Deterioration in Modern Populations, 2nd Revised Edition - by Richard Lynn.
- Race, Dysgenics, and the Survival of the West - interview with Richard Lynn.
- The Decline of the West - review and description of the book Dysgenics.
- Sacrificing the Best
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 Richard Lynn. Dysgenics: Genetic Deterioration in Modern Populations. 2nd Revised Edition. 2011. Ulster Institute for Social Research
- ↑ Dysgenics. Merriam-Webster. http://www.merriam-webster.com/medical/dysgenics
- ↑ Dysgenics. Dictionary.com. http://dictionary.reference.com/browse/dysgenics?
- ↑ 4.0 4.1 Edward Dutton, Richard Lynn. (2015). A negative Flynn Effect in France, 1999 to 2008–9. Intelligence, 51, 67–70. https://www.sciencedirect.com/science/article/pii/S0160289615000653
- ↑ 5.0 5.1 Michael A. Woodley of Menie, Curtis S. Dunkel. (2015). In France, are secular IQ losses biologically caused? A comment on Dutton and Lynn (2015). Intelligence, 53, 81–85. https://www.sciencedirect.com/science/article/pii/S0160289615001221
- ↑ 6.0 6.1 Dutton, E., van der Linden, D., & Lynn, R. (2016). The negative Flynn Effect: A systematic literature review. Intelligence. http://www.sciencedirect.com/science/article/pii/S0160289616300198
- ↑ 7.0 7.1 Donald I. Templer. The Comparison of Mean IQ in Muslim and Non-Muslim Countries. Mankind Quarterly, Vol. 50, No. 3 (Spring 2010) pp. 188-209. http://www.mankindquarterly.org/spring2010_templer.html
- ↑ 8.0 8.1 8.2 8.3 The Decline of the West. October 2011. American Renaissance. http://www.amren.com/features/2011/12/the-decline-of-the-west/
- ↑ Graham RK (Fall 1998). "Devolution by revolution: Selective genocide ensuing from the French and Russian revolutions". Mankind Quarterly 39 (11): 71–93.
- ↑ Jordan, David Starr (2003 (Reprint)). War and the Breed: The Relation of War to the Downfall of Nations. University Press of the Pacific. ISBN 1-4102-0900-8.
- ↑ Holloway, S. M.; Smith, C. (1975). "Effects of various medical and social pracitices on the frequency of genetic disorders". American Journal of Human Genetics 27 (5): 614–627. http://www.ncbi.nlm.nih.gov/pubmed/1163536
- ↑ Matsunaga, E. (1983). "Perspectives in mutation epidemiology: 5. Modern medical practice versus environmental mutagens: Their possible dysgenic impact". Mutation Research/Reviews in Genetic Toxicology 114 (3): 449–457. http://dx.doi.org/10.1016/0165-1110(83)90040-4
- ↑ http://www.thesebrokenvases.com/2010/10/down-syndrome-awareness-can-people-with.html
- ↑ Lynn, R. (2008). "Dysgenic fertility for criminal behaviour". Journal of Biosocial Science 27 (4). http://dx.doi.org/10.1017/S0021932000023014
- ↑ 15.0 15.1 Meisenberg, Gerhard (2010). "The reproduction of intelligence". Intelligence 38 (2): 220–230. http://dx.doi.org/10.1016/j.intell.2010.01.003
- ↑ Helmuth Nyborg, The decay of Western civilization: Double relaxed Darwinian Selection, Personality and Individual Differences, Volume 53, Issue 2, July 2012, Pages 118-125, ISSN 0191-8869, 10.1016/j.paid.2011.02.031 http://www.sciencedirect.com/science/article/pii/S0191886911001073
- ↑ Michael A. Woodley, Jan te Nijenhuis, Raegan Murphy, Were the Victorians cleverer than us? The decline in general intelligence estimated from a meta-analysis of the slowing of simple reaction time, Intelligence, Available online 7 May 2013, ISSN 0160-2896, 10.1016/j.intell.2013.04.006 http://www.sciencedirect.com/science/article/pii/S0160289613000470
- ↑ Yulia A. Dodonova, Yury S. Dodonov, Is there any evidence of historical slowing of reaction time? No, unless we compare apples and oranges, Intelligence, Volume 41, Issue 5, September–October 2013, Pages 674-687, ISSN 0160-2896, http://dx.doi.org/10.1016/j.intell.2013.09.001
- ↑ Irwin W. Silverman, Testing the hypothesized effect of dysgenic fertility on intelligence with existing reaction time data: A comment on Woodley, te Nijenhuis, and Murphy (2013), Intelligence, Volume 41, Issue 5, September–October 2013, Pages 664-666, ISSN 0160-2896, http://dx.doi.org/10.1016/j.intell.2013.08.008
- ↑ Ted Nettelbeck. (2014). Smarter but slower? A comment on Woodley, te Nijenhuis & Murphy (2013). Intelligence, Volume 42, January–February 2014, Pages 1–4. https://www.sciencedirect.com/science/article/pii/S0160289613001347
- ↑ Scott Parker. (2014). Were the Victorians cleverer than us? Maybe, maybe not. Intelligence, Volume 47, November–December 2014, Pages 1–2. https://www.sciencedirect.com/science/article/pii/S016028961400107X
- ↑ Michael A. Woodley, Jan te Nijenhuis, Raegan Murphy. (2014). Is there a dysgenic secular trend towards slowing simple reaction time? Responding to a quartet of critical commentaries. Intelligence, Volume 46, September–October 2014, Pages 131–147. https://www.sciencedirect.com/science/article/pii/S0160289614000841
- ↑ Michael A. Woodley of Meniea, Jan te Nijenhuis, Raegan Murphy. (2015). Do variable signal luminances and confounded stimuli contribute to slowing simple RT and cross study heterogeneity? A response to Parker (2014). Intelligence, Volume 49, March–April 2015, Pages 23–24. https://www.sciencedirect.com/science/article/pii/S0160289614001834
- ↑ Michael A. Woodley of Menie, Heitor B.F. Fernandes. (2015). Do opposing secular trends on backwards and forwards digit span evidence the co-occurrence model? A comment on Gignac (2015). Intelligence. Volume 50, May–June 2015, Pages 125–130. https://www.sciencedirect.com/science/article/pii/S0160289615000410
- ↑ Jakob Pietschnig, Georg Gittler. A reversal of the Flynn effect for spatial perception in German-speaking countries: Evidence from a cross-temporal IRT-based meta-analysis (1977–2014). Intelligence, Volume 53, November–December 2015, Pages 145–153. https://www.sciencedirect.com/science/article/pii/S0160289615001336
- ↑ Michael A. Woodley of Meniea, Heitor B.F. Fernandes. (2016). Showing their true colours: Possible secular declines and a Jensen effect on colour acuity — More evidence for the weaker variant of Spearman's Other Hypothesis. Personality and Individual Differences, Volume 88, January 2016, Pages 280–284. https://www.sciencedirect.com/science/article/pii/S0191886915005826
- ↑ Madison, G., of Menie, M. A. W., & Sänger, J. (2016). Secular Slowing of Auditory Simple Reaction Time in Sweden (1959–1985). Frontiers in Human Neuroscience, 10. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4988978/
- ↑ 28.0 28.1 Michael A. Woodley of Menie, Heitor B.F. Fernandes. (2015). The secular decline in general intelligence from decreasing developmental stability: Theoretical and empirical considerations. Personality and Individual Differences, Volume 92, April 2016, Pages 194–199. https://www.sciencedirect.com/science/article/pii/S0191886915301161
- ↑ Menie, M. A. W., Piffer, D., Peñaherrera, M. A., & Rindermann, H. (2016). Evidence of contemporary polygenic selection on the Big G of national cognitive ability: A cross-cultural sociogenetic analysis. Personality and Individual Differences, 102, 90-97 http://www.sciencedirect.com/science/article/pii/S0191886916308042
- ↑ Weyl, N. & Possony, S. T: The Geography of Intellect, 1963, s. 154
- ↑ Van Court, Marian (1983). "Unwanted Births And Dysgenic Reproduction In The United States". Eugenics Bulletin. http://www.prometheism.net/dysgenic2/
- ↑ Wang, M., Fuerst, J., & Ren, J. (2016). Evidence of dysgenic fertility in China. Intelligence, 57, 15-24. http://www.sciencedirect.com/science/article/pii/S0160289616301106
- ↑ Chen, H. Y., Chen, Y. H., Liao, Y. K., Chen, H. P., & Lynn, R. (2017). Dysgenic fertility for intelligence and education in Taiwan. Intelligence, 63, 29-32. http://www.sciencedirect.com/science/article/pii/S0160289616303038
- ↑ Lynn, R., & Yadav, P. (2015). Differences in cognitive ability, per capita income, infant mortality, fertility and latitude across the states of India. Intelligence, 49, 179-185. http://www.sciencedirect.com/science/article/pii/S0160289615000148
- ↑ 35.0 35.1 35.2 Lynn, R.; Harvey, J. (2008). "The decline of the world's IQ". Intelligence 36 (2): 112. http://dx.doi.org/10.1016/j.intell.2007.03.004
- ↑ Meisenberg, Gerhard (2009). "Wealth, Intelligence, Politics and Global Fertility Differentials". Journal of Biosocial Science 41 (04): 519. http://dx.doi.org/10.1017/S0021932009003344
- ↑ Preston SH, Campbell C (March 1993). "Differential Fertility and the Distribution of Traits: The Case of IQ". The American Journal of Sociology 98 (5): 997–1019. The University of Chicago Press. doi:10.1086/230135.
- ↑ Coleman JS (1993). "Comment on Preston and Campbell's 'Differential Fertility and the Distribution of Traits'". The American Journal of Sociology 98 (5): 1020–1032. doi:10.1086/230136.
- ↑ Lam D (March 1993). "Comment on Preston and Campbell's "Differential Fertility and the Distribution of Traits"". The American Journal of Sociology 98 (5): 1033–1039. The University of Chicago Press. doi:10.1086/230137.
- ↑ National IQ Means Transformed from Programme for International Student Assessment (PISA) Scores, and their Underlying Gene Frequencies, Volkmar Weiss, The Journal of Social, Political and Economic Studies 1.34(2009): pp. 71–94
- ↑ Michael A. Woodley of Menie. (2015). How fragile is our intellect? Estimating losses in general intelligence due to both selection and mutation accumulation. Personality and Individual Differences, Volume 75, March 2015, Pages 80–84. https://www.sciencedirect.com/science/article/pii/S0191886914006278
- ↑ Dutton, E., Bakhiet, S. F., Ziada, K. E., Essa, Y. A. S., & Blahmar, T. A. M. (2017). A Negative Flynn Effect in Khartoum, the Sudanese capital. Intelligence, 63, 51-55. http://www.sciencedirect.com/science/article/pii/S0160289617300193
- ↑ Dutton, E., Bakhiet, S. F., Essa, Y. A. S., Blahmar, T. A. M., & Hakami, S. M. A. (2017). A Negative Flynn Effect in Kuwait: The same effect as in Europe but with seemingly different causes. Personality and Individual Differences, 114, 69-72. http://www.sciencedirect.com/science/article/pii/S0191886917302301
- ↑ (2010) "The rise and fall of the Flynn Effect as a reason to expect a narrowing of the Black–White IQ gap". Intelligence 38 (2): 213–219. doi:10.1016/j.intell.2009.12.002. ISSN 01602896.
- ↑ Woodley, M. A., & Meisenberg, G. (2013). A Jensen effect on dysgenic fertility: An analysis involving the National Longitudinal Survey of Youth. Personality and individual differences, 55(3), 279-282. https://www.sciencedirect.com/science/article/pii/S0191886912002607
- ↑ Michael A. Woodley, Gerhard Meisenberg. (2013). In the Netherlands the anti-Flynn effect is a Jensen effect. Personality and Individual Differences, Volume 54, Issue 8, June 2013, Pages 871–876 https://www.sciencedirect.com/science/article/pii/S0191886913000056
- ↑ Hannah Peach, Jordan E. Lyerly, Charlie L. Reeve. (2014). Replication of the Jensen effect on dysgenic fertility: An analysis using a large sample of American youth. Personality and Individual Differences, Volume 71, December 2014, Pages 56–59. https://www.sciencedirect.com/science/article/pii/S0191886914004139
- ↑ Intelligence of Norwegians and Danes on the wane, say researchers https://www.thelocal.no/20171228/intelligence-of-norwegians-and-danes-on-the-wane-say-researchers
- ↑ IQ decline and Piaget: Does the rot start at the top? https://www.sciencedirect.com/science/article/pii/S0160289617302787
- ↑ Murray, C. (2003). Human accomplishment: The pursuit of excellence in the arts and sciences, 800 BC to 1950. New York, NY: Harper Collins.
- ↑ Huebner, J. (2005). A possible declining trend for worldwide innovation. Technological Forecasting and Social Change, 72, 980–986. https://www.sciencedirect.com/science/article/pii/S0040162505000235
- ↑ Woodley, M. A. (2012). The social and scientific temporal correlates of genotypic intelligence and the Flynn effect. Intelligence, Volume 40, Issue 2, March–April 2012, Pages 189–204. https://www.sciencedirect.com/science/article/pii/S0160289611001620
- ↑ Race, Dysgenics, and the Survival of the West. The Occidental Letter, vol. 1, no. 1 (Fall 2007): 1, 4–6 http://toqonline.com/archives/v7n3/734Lynninterview.pdf
- ↑ Helmuth Nyborg. Western countries get dumber by the day. 21 September 2012. Dispatch International. http://eugenik.dk/static/pdf/2012/DispatchInternational21Sep2012en.pdf