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iunie 6, 2017

Davide Piffer published the polygenic scores resulted from 15 leading SNP found by the most recent GWAS on intelligence (Sniekers, 2017):  http://rpubs.com/Daxide/279148

These scores suggest no significant increase of the intelligence of Western Eurasians since Out of Africa. Today differences in intelligence between Africans and Europeans are due rather of a higher decrease of intelligence of Africans than Europeans since Out of Africa.

The POLY IQ of super-populations from 1000 GENOMES are: AFR-0.4714, SAS-0.4439, EUR-0.4627, EAS-0.5129, AMR-0.4515.

All of these 15 SNP increase the intelligence of Europeans. It is expected fewer of them increase the intelligence of SAS, even fewer of EAS and the fewest of AFR, because genetic distances and times since divergence between these populations.

We can suppose that in the moment of Out of Africa, the Africans and the future non-Africans have roughly the same polygenic scores on these 15 SNP. We can suppose the polygenic score increase during last 60,000 years in all populations. If non-Africans ancestors are also the ancestors of LWK (today LWK have the lowest polygenic score of today Africans: 0.4567), the increase of the polygenic score in EUR is only 0.01 higher than the increase of LWK during last 60,000 years. But if the ancestors of the non-Africans are not the ancestors of LWK, the frequency of these 15 variants increased more in Africans than in Europeans since the Out of Africa, because all the other today Africans (excepting LWK) have higher polygenic scores than the average of Europeans. Also, the frequency increased more in Africans than in South Asians. This results are in line with polygenic scores on EDU, obtained with the 74 SNP found by the GWAS of Okbay (2016): ASW have the same score with IBS and TSI, and higher score than CEU and GBR. Also, CEU have lower score than all Africans, excepting LWK. (The GWAS on EDU find not only IQ-increasing SNP, but also SNP that favor „domestication”, and these common variants spread due of civilization. For example, peoples that entered faster in Neolithic and complex civilization, like IBS and TSI, have 0.01-0.02 higher scores on EDU-SNP and 0.02 lower scores on IQ-SNP than peoples that had latter entrance in sedentary civilizations, like CEU, GBR, FIN.)

Althought, Racimo (2017) found selection on polygenic score on educational attainment only for EAS, and not for other populations or super-populations of 1000 GENOMES, and this selection in EAS produced before 10,000 years ago. If there was not positive selection on EDU, the genotypic EDU decreased due of the increase of rare variants detrimental to EDU, produced by de novo mutations. It is necessary a positive selection on a complex trait (and an increase of polygenic score) to maintain this trait at the actual level. Hence, the result of Racimo (2017) demonstrates that genotypic EDU decreased in all populations during Holocene, and decreased in all (super)populations excepting EAS between Out of Africa and Holocene. But it is probable there were some periods of selection on EDU in Europeans during last 60,000 years, because all GWAS did not find any common SNP that decreases barely 1 or to 2 IQ points the genotypic EDU, hence the IQ-decreasing SNP did not reach the frequency of common polymorphism in Europeans. The alternation of periods of positive selection and periods of negative selection could explain too the fact, noticed by Piffer (2016), that there are 45% ancestral alleles between IQ-increasing SNP found by the GWAS of Okbay (2016). During periods of selection against high intelligence, IQ-decreasing variants could reach the frequency of common polymorphism. Also, EUR have fewer IQ-increasing ancestral alleles than EAS, and this fact could be due of the spread of IQ-decreasing derived alleles during longer (or stronger) periods of negative selection on IQ in EUR than in EAS.

Although, the selection against high-IQ did not produce only after Industrial Revolution. De la Croix (2017) found Upper class (presumed also the most intelligent social class) had the lowest fertility in pre-industrial England.

It would be very strange a higher increase of the frequency of some neutral alleles in Africans, and a lower increase of the same beneficial alleles in Europeans during 2,000 generations. It is more probable these 15 SNP (and the other IQ-increasing SNP) were under a soft selection in Europeans, and partially in other populations, the most of last 60,000 years. It is more probable too these IQ-increasing common SNP were selected against in all the populations (mostly in Europeans, South Asians and Native Americans) during some periods that favored selection against high-intelligence: Neolithic transition, entrance in complex civilizations and Industrial Revolution. This selection against high intelligence decreased the polygenic scores more in Europeans, South Asians and Amerindians than in Africans, because many of these alleles are not related to intelligence in Africans and are not influenced by the selection against high-IQ. During periods of soft selection for high-IQ, like in European Metal Ages and Medieval Age (Woodley & Piffer, 2017), the polygenic score could increase even if genotypic intelligence remains constant or even decreases, because the detrimental effect of de novo mutations is partially compensated by the increase of polygenic score, and only partially compensated by elimination of deleterious de novo mutations and other rare alleles. The frequency of these common SNP could increase even if the selection on intelligence is zero, due of pleiotropy of some of them, and of selection on other complex traits.

Even if not all these 15 SNP increase the IQ of East Asians, their polygenic score is 0.05 higher than in Europeans. This is in line with all polygenic scores on educational attainment, resulting after the counts of SNP found by the GWAS of Rietveld (2013), Davies (2016) and Okbay (2016). All of these counts found 0.05 higher POLY EDU of East Asians than of Europeans and other Eurasians. Probable many (or even mostly) of the IQ-increasing mutations in linkage with SNP found by different GWAS are older than the divergence of Europeans and East Asians, and these mutations increase the intelligence of both populations. The 0.05 higher polygenic score of all East Asians (in 1000 GENOMES and in ALFRED too) than Europeans demonstrates a strong selection on intelligence of East Asians. It is near zero probability that the same very strong selection pressure operated on Eastern Siberian hunter-gatherers and on Vietnamese and Han farmers during Holocene. It is more probable this high selection on intelligence operated before Holocene, before the separation of different populations of East Asians, but after the split of Native Americans, that have 0.06 lower polygenic score than East Asians, and that diverged from East Asians 23,000 years ago (Raghavan, 2015). Also, Northern East Asians have higher POLY IQ than Southern East Asians, due of the dilution of Northern Han Chinese during Southward migration. But Japanese have the highest POLY IQ of EAS, even higher than Northern Han Chinese, and it means the increase of the strong selection on IQ of East Asians produced before the divergence of Jomons, estimated 22,000-23,000 years ago (Kanazawa-Kiriyama, 2017). The most probable this strong selection on intelligence of East Asians produced during Last Glacial Maximum.

After this high increase of the genotypic intelligence of East Asians, the selection pressure relaxed and probably their intelligence decreased during Holocene, due of warmer climate and of civilizations, mostly by accumulation of IQ-decreasing rare variants.

The Eastern Asian Cro-Magnon living during Last Glacial Maximum had the highest genotypic intelligence of all humans ever living on the Earth.

Finally, I would like to draw attention to some proof, which I find indisputable,
of the superiority of Palaeolithic man to modern man in terms of visual-spatial
intelligence and memory. A study that analyzed how accurately quadrupedal
walking was rendered in 1000 works of art from the Palaeolithic and modern times
found an error rate of 46.2% in Palaeolithic artists, of 83.5% in artists before 1887,
and of 57.9% in artists after 1887, the year when Eadweard Muybridge published
a series of 20,000 photographs investigating the stages of animal locomotion
(Horvath et al., 2012). Furthermore, Cro-Magnons had an error rate even lower
than the rate of those illustrating animal anatomy books, of 63.6%, and they were
very close to the error rate of taxidermists of natural history museums, of 41.1-
43.1% (Horvath et al., 2009).

The loss of (visuo-spatial) intelligence of modern man compared to Paleolithic man should not surprise us. Today, untrained and even trained adult man has a working memory for numbers lower than that of a young trained chimpanzee (Inoue, 2007; Matsuzawa, 2009; Cook, 2010). Also, chimpanzee choice rates in competitive games match equilibrium game theory predictions. Chimpanzee’s choices are close to the equilibrium predictions and are more responsive than human choices to past history and to payoff changes (Martin, 2014). Also, baboons but not modern humans break cognitive set in a visuo-motor task, indicating greater mental flexibility (Pope, 2015). Furthermore, Koko the gorilla, at 43 to 65 month, scored between 85.2 and 91.7 IQ points on the Stanford-Binet intelligence test (Patterson, 1993), surpassing many living humans who already benefited by Lynn-Flynn effect at that time, in 1975-1976.



Cook, Peter & Wilson, Margaret (2010) Do young chimpanzees have extraordinary working memory?Psychonomic Bulletin & Review 17(4): 599-600

Davies, G., Marioni, R.E., Liewald, D.C., Hill, W.D., Hagenaars, S.P.,… & Deary, I.J. (2016). Genome-wide association study of cognitive functions and educational attainment
in UK Biobank (N=112,151). Molecular Psychiatry 1-10.

De la Croix, D. et al (2017) “Decessit sine prole” – Childlessness, Celibacy, and Survival of the Richest in Pre-Industrial England. CEPR Discussion Paper No. DP11752. Available at SSRN: https://ssrn.com/abstract=2896042

Horvath, G., Csapo, A., Nyeste, A., Gerics, B., Csorba, G. et al. (2009). Erroneous quadruped walking depictions in natural history museums. Current Biology 19: 61-62.

Horvath, G., Farkas, E., Boncz, I., Blaho, M. & Kriska, G. (2012). Cavemen were better at depicting quadruped walking than modern artists: Erroneous walking illustrations in the fine arts from prehistory to today. PLoS ONE 7(12): e49786

Inoue, Sana & Matsuzawa, Tetsuro (2007) Working memory of numerals in chimpanzees. Current Biology 17(23): 1004-1005

Kanazawa-Kyryiama, H. (2017) A partial nuclear genome of the Jomons who lived
3000 years ago in Fukushima, Japan. Journal of Human Genetics 62: 213–221

Martin, Cristopher F. et al (2014) Chimpanzee choice rates in competitive games match equilibrium game theory predictions. Scientific Reports 4: 5182 doi: 10.1038/srep05182

Matsuzawa, Tetsuro (2009) Symbolic representation of number in chimpanzees. Current Opinion in Neurobiology 19: 92–98

Okbay, A., Beauchamp, J.P., Fontana, M.A., Lee, J.J., Pers, T.H., Rietveld, C., & Benjamin, D.J. (2016). Genome-wide association study identifies 74 loci associated with educational attainment. Nature 533: 539-542.

Patterson, Francine & Gordon, Wendy (1993) The Case for the Personhood of Gorillas.In Paola Cavalieri& Peter Singer (eds.) The Great Ape Project. New York: St. Martin’s Griffin, pp. 58-77

Piffer, D. (2017)  2017 Intelligence GWAS: Group-level polygenic scores http://rpubs.com/Daxide/279148

Pope, Sarah M. et al (2015) Baboons (Papio papio), but not humans, break cognitive set in a visuomotor task. Animal Cognition 18:1339–1346

Raghavan, M. (2015) Genomic evidence for the Pleistocene and recent population history of Native Americans. Science Vol. 349, Issue 6250, aab3884 DOI: 10.1126/science.aab3884

Racimo, F. et al (2017) Detecting polygenic adaptation in admixture graphs. bioRxiv doi: http://dx.doi.org/10.1101/146043

Rietveld, C.A., Medland, S.E., Derringer, J., Yang, J., Esko, T., & Koellinger, P.D. (2013). GWAS of 126,559 individuals identifies genetic variants associated with educational attainment. Science 340: 1467-1471.

Sniekers, S. et al (2017) Genome-wide association meta-analysis of 78,308 individuals identifies new loci and genes influencing human intelligence. Nature Genetics doi:10.1038/ng.3869

Woodley, M.A. et al. (2017) Holocene selection for variants associated with cognitive ability: Comparing ancient and modern genomes. bioRxiv http://dx.doi.org/10.1101/109678


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