[Sérieux] Ethno-différencialisme, race-realism, génétique et courbe en cloche

[Vilfredo]

Non je regarderai

Dautres idées?

[Lameador]

23 hours ago, Lameador said:

As-tu étudié le rôle des structures familiales, de la religion et des méthodes d'éducation chez les graines de maïs ?

 

22 hours ago, Vilfredo said:

Non je regarderai

 

Oui, regardes sérieusement.

La fausse identité entre "héritable" et "génétique", lorsqu'elle est appliquée aux êtres humains, est une source de nombreuses erreurs et abjections (dont la justification scientifique du racisme).

De sa naissance, on n'hérite pas seulement de 46 (ou 47 pour les électeurs de Poutou) chromosomes.

[Lancelot]

 

On 4/13/2022 at 11:25 AM, Vilfredo said:

Je lis Lewontin et sa polémique avec Jensen et je tombe sur cet argument: (dans "Race and intelligence", 1970)

Ex de RCL: Si je prends deux séries de graines de maïs sans variation génétique (inbred) et que je les plante, je vais découvrir des différences de taille, et chaque série aura sa différence moyenne. Mais comme ces séries de graines sont génétiquement différentes (? j'ai dû oublier la différence entre genetic variation et genetic difference), j'aurai une différence génétique avec une héritabilité de 0. L'argument, bien sûr, c'est que Jensen est dans le cas exactement opposé. Donc ses études ne nous disent rien sur la différence génétique et l'héritabilité. C'est l'un ou l'autre. Un seul ddl tout ça.

 

Vous en pensez quoi? Lewontin n'a pas été très cité dans ce topic (seulement dans la biblio du wot de @Lancelot)

 

J'ai l'impression que ça recoupe pas mal ce que je disais justement dans le wall of text:

On 1/11/2018 at 4:57 PM, Lancelot said:

QI et héritabilité

L'héritabilité est définie comme la proportion de variation d'un attribut entre les individus d'une population corrélée à la variation génétique dans cette population. Si le QI a une héritabilité de .50 alors on peut dire que 50% de la variation des scores de QI est potentiellement attribuable à des influences génétiques. La corrélation entre deux variables étant indépendante de leur niveau moyen, augmenter tous les QI d'une population de 200 points ne changera en rien le score d'héritabilité. Cette mesure est donc muette sur l'évolution possible des scores de QI (leur modifiabilité). La taille est un exemple de caractéristique extrêmement héritable (à un niveau supérieur à .90) mais également très modifiable comme l’illustre l'augmentation de la taille moyenne des dernières générations. L'héritabilité étant toujours mesurée pour une population, elle n'a aucun pouvoir explicatif sur les différences entre populations. La différence de taille entre deux populations peut être complètement liée à des facteurs environnementaux (nutrition, maladies...) sans que le score d'héritabilité de ces populations soit affecté.
L'héritabilité peut être calculée avec plusieurs méthodes, la plus récente et directe étant la "genome-wide association study". L'héritabilité du QI a été estimée par l'une de ces études entre .40 et .50 (Davies et al., 2011) et par une autre à .35 (Kirkpatrick et al., 2014). Un tel score n'est pas surprenant pour une mesure qui se veut aussi générale que le QI. En effet il est connu que les traits définis les plus largement sont les plus héritables (Johnson et al., 2011). À titre de comparaison, Polderman et al. (2015) ont passé en revue 2748 études sur les jumeaux et trouvé une héritabilité moyenne de .48 pour environ 18 000 traits complexes. L'âge de la population considérée peut altérer l'héritabilité. Par exemple l'héritabilité de la satisfaction au travail a été mesurée à .312 à 21 ans, .187 à 25 ans et .198  à 30 ans (Li et al., 2016). Dans le cas du QI elle tend à augmenter jusqu'à atteindre des valeurs autour de .70 à l'âge adulte, ce qui a été nommé l'effet Wilson (Bouchard 2013). Cela peut s'expliquer en partie par le fait que, lorsqu'ils ont la liberté de le faire, les individus tendent à avoir un parcours de vie correspondant à leurs capacités physiques et intellectuelles (Kristof-Brown & Guay 2010). D'autres facteurs tels que l'éducation et l'environnement familial peuvent également altérer l'héritabilité du QI (Bates et al. 2013, Taylor et al. 2010).

 

Ceci étant, pour rester dans la même veine, j'ai pensé à ce thread récemment en tombant sur ce papier que j'ai trouvé intriguant :

Quote

Graham, J. H. (2022). Random Developmental Variation of Human Phenotypic Traits, as Estimated by Fluctuating Asymmetry and Twin Studies. İstanbul Antropoloji Dergisi, (1), 1–10.

 

Random developmental variation, or developmental noise, contributes to total phenotypic variation in the human species. Despite exhortations to examine it, especially with respect to human behavior and intelligence, there has been little research specifically devoted to doing so. Random developmental variation can be estimated in studies of fluctuating asymmetry and comparisons of monozygotic and dizygotic twins. Estimation of random developmental variation requires that both genotype and environment be held constant. In a small sample of bilaterally symmetrical traits (dermatoglyphic ridge counts, digit lengths, ear lengths and widths), I show how the random developmental component can be estimated. In these traits, the percentage of total phenotypic variation attributable to developmental noise ranges from 3 percent to more than 25 percent. Moreover, for dermatoglyphic ridge counts, fluctuating asymmetry and twin comparisons give essentially the same estimates.

 

 

[Lancelot]

On 4/15/2022 at 4:05 PM, Lancelot said:

ce papier que j'ai trouvé intriguant

Et maintenant celui-ci qui cite le premier.

 

Quote

Lajus, D. (2022). God playing dice, revisited: determinism and indeterminism in studies of stochastic phenotypic variation. Emerging Topics in Life Sciences.

 

Empirical studies of phenotypic variation show that genetic and environmental heterogeneity account for only part of it. Usually, the magnitude of the residual variation is comparable with that of the genetic component, while notably exceeding the magnitude of the environmental component. This can be interpreted in two ways. A deterministic interpretation associates it with artifacts such as measurement error and genetic and environmental heterogeneity that is unaccounted for. An indeterministic interpretation argues that it is random or stochastic phenotypic variation (SPV) resulting from developmental instability — a developing organism's inability to produce a consistent phenotype in a given environment. Classical example of debates between determinists and indeterminists took place about a century ago in quantum physics. In discussing Heidelberg's Uncertainty Principle, Einstein metaphorically expressed his deterministic position: ‘God does not play dice with universe'. The indeterministic Uncertainty Principle, however, was eventually widely accepted. Currently, most biologists implicitly or explicitly support deterministic interpretations of phenotypic variation patterns. Here, a wide range of data on morphological traits (studied with analysis of fluctuating asymmetry) and non-morphological traits are analyzed to provide evidence that SPV is not an artifact, but a valid phenomenon. This evidence supports conclusions that observed associations between SPV and stress can be analyzed in the framework of dynamic energy budget theory, and are inextricably linked through energy homeostasis.

 

J'ai conscience que pour l'instant c'est très loin d'être une hypothèse influente ou même mature, mais trancher la question "c'est inné" vs "c'est acquis" par "c'est contingent" a un côté Gouldien qui me séduit.

[Pegase]

J'ai eu une discussion assez étrange il y a peu. Un type me soutenait que le comportement était surtout dû à l'environnement et que la biologique jouait un rôle infime. Le type était anti-speciste et me soutenait que finalement il n'y avait aucune différence entre le comportement d'un tigre et celui d'un chat (si ce n'est la taille)

 

Ça me semblait aller contre tout ce que je croyais dans le domaine des races de chiens. Il me semblait plutôt bien établi qu'il y avait une influence génétique dans leur comportement.

Je suis tombé sur cette étude qui semble aller contre cette image répandue.

https://www.science.org/doi/10.1126/science.abk0639

 

Certains ici ont des connaissances plus poussées en la matière ?

[Lancelot]

31 minutes ago, Pegase said:

Le type était anti-speciste

Voilà ton erreur, fallait arrêter la conversation à ce moment là.

[PABerryer]

Un lyssenkiste, cela existe donc encore !

[Rincevent]

il y a 43 minutes, Pegase a dit :

J'ai eu une discussion assez étrange il y a peu. Un type me soutenait que le comportement était surtout dû à l'environnement et que la biologique jouait un rôle infime. Le type était anti-speciste et me soutenait que finalement il n'y avait aucune différence entre le comportement d'un tigre et celui d'un chat (si ce n'est la taille)

 

Ça me semblait aller contre tout ce que je croyais dans le domaine des races de chiens. Il me semblait plutôt bien établi qu'il y avait une influence génétique dans leur comportement.

Je suis tombé sur cette étude qui semble aller contre cette image répandue.

https://www.science.org/doi/10.1126/science.abk0639

 

Certains ici ont des connaissances plus poussées en la matière ?

Citation

Modern domestic dog breeds are only ~160 years old and are the result of selection for specific cosmetic traits.

Bah non, pas toutes. Depuis l'Antiquité, tu as des chiens sélectionnés pour la chasse (pour le gibier classique, comme pour le gibier d'eau), d'autres pour chasser les nuisibles sous terre, d'autres pour garder un lieu ou pour garder un troupeau, d'autres pour la course, d'autres encore même pour leur pilosité. Donc la vingtaine d'auteurs sont bien gentils, mais ce serait bien qu'au moins l'un d'entre eux se renseigne avant de raconter des conneries dès la première phrase. Dire qu'un "Most" ajouté en premier mot aurait suffi à éviter de paraître aussi débile... (Évidemment, si Science publie une telle merde, il ne faut plus s'étonner que les gens aient des doutes sur les procédures de revue par les pairs).

 

Much soyance. Very knowledge. So facts. Wow.

 

Et pour en revenir au sujet de base, lecture impérative : https://www.amazon.fr/Blueprint-How-DNA-Makes-Who/dp/0141984260/

[Bisounours]

il y a 14 minutes, Rincevent a dit :

pour le rapport du gibier d'eau, entre autres fonctions

Des races aux pattes palmés

https://www.lescharmilles.ch/wp/5-races-de-chiens-aux-pattes-palmees/

 

[Philiber Té]

il y a 28 minutes, Rincevent a dit :

Bah non, pas toutes. Depuis l'Antiquité, tu as des chiens sélectionnés pour la chasse (pour le gibier classique, comme pour le gibier d'eau), d'autres pour chasser les nuisibles sous terre, d'autres pour garder un lieu ou pour garder un troupeau, d'autres pour la course, d'autres encore même pour leur pilosité. Donc la vingtaine d'auteurs sont bien gentils, mais ce serait bien qu'au moins l'un d'entre eux se renseigne avant de raconter des conneries dès la première phrase. Dire qu'un "Most" ajouté en premier mot aurait suffi à éviter de paraître aussi débile... (Évidemment, si Science publie une telle merde, il ne faut plus s'étonner que les gens aient des doutes sur les procédures de revue par les pairs).

 

Much soyance. Very knowledge. So facts. Wow.

 

Et pour en revenir au sujet de base, lecture impérative : https://www.amazon.fr/Blueprint-How-DNA-Makes-Who/dp/0141984260/

 

"Before the 1800s, dogs were probably primarily selected for functional roles such as hunting, guarding, and herding. Modern dog breeds are a recent invention defined by conformation to a physical ideal and purity of lineage."

 

[Bézoukhov]

 

Sur une période de temps assez courte toutefois.

[Pegase]

https://youtu.be/kqzwCk0Ha5E

 

Longue vidéo sur le sujet, si ça en intéresse certains.

[Lancelot]

Alors je suis très peu tenté de regarder la vidéo parce que lol.

En revanche ils ont le bon goût de donner des références (de manière un peu brouillonne certes mais je ne peux pas trop leur en vouloir) dont certaines m'intéressent, notamment sur les twin studies (dont je j'avais pas réalisé qu'il y a visiblement tout un courant pour les critiquer) et l'héritabilité (où je trouverais peut-être un développement plus formel de mes propres critiques). Par contre leur traitement partial m'oblige à faire moi-même le boulot d'aller voir qui a cité ces papiers et pourquoi (pour les approuver, les désapprouver, apporter des éléments pour ou contre...).

 

Par exemple je vois Kamin, L. J., & Goldberger, A. S. (2002). Twin studies in behavioral research: a skeptical view. Theoretical population biology, 61(1), 83-95.

Quote

We review in detail two major ongoing research projects that employ samples of twins reared apart (and in one case, twins reared together). The studies attempt, via model fitting, to estimate proportions of genetic and environmental variance for many human traits. We discuss problems concerning the representativeness of samples, the accuracy and reliability of the data, the extent of contact of nominally separated twins, the measurement of selective placement effects, and the particular model-fitting procedures. The two studies agree in their conclusions, but we do not find the conclusions to be convincing. We suggest that no scientific purpose is served by the flood of heritability estimates generated by these studies.

 

Ok ça semble prometteur, mais 2002 ça date. Google scholar me dit qu'il y a 108 citations dont la plus récente en 2022 dans Joseph, J. (2022). A Reevaluation of the 1990 “Minnesota Study of Twins Reared Apart” IQ Study. Human Development, 66(1), 48-65. Voici ce qui en est dit :

Quote

Criticism of TRA Studies

 

Over the years, commentators have described many biases and problems found in TRA studies, especially those that, like the MISTRA, Newman et al. (1937), and Shields (1962) studies, were based on volunteer twins (Joseph, 2015, chapter 3). Psychologist Leon Kamin was a pioneering analyst of TRA research (Joseph, 2018; Kamin, 1974), and psychologist Susan Farber (1981) published an exhaustive critical analysis of the three TRA studies conducted prior to the MISTRA.

 

Detailed case history information was provided only by the authors of the first three TRA studies (Juel-Nielsen, 1965/1980; Newman et al., 1937; Shields, 1962). I have compiled some characteristics of these studies’ combined sample of 75 MZA pairs: (a) in 25/75 (33%) of the pairs, twins were separated at 12 months of age or later; (b) in 56/75 (75%) of the pairs, twins had contact with each other while growing up; (c) in 42/75 (56%) of the pairs, one or both twins were placed with a family member; and (d) in 17/75 (23%) of the pairs, twins lived together for a period of at least 12 months after separation, or grew up next door to each other. (For specific examples of twins’ late/inadequate separation and prestudy contact found in these 75 case histories, see Joseph, 2015, Tables 2.1–2.3).

 

For these and other reasons, Farber accurately concluded, “the assumption that this is a sample of reared-apart twins is incorrect. Most were reared apart only partially, and almost all had contact with each other by the time they were studied” (Farber, 1981, p. 19).

 

Additional problems, biases, and potential environmental confounds described by critics of TRA research include (a) the fact that twins share a prenatal environment (Farber, 1981); (b) the selective placement of twins and the lack of random assignment (Fancher, 1985; Farber, 1981; Kamin, 1974; Taylor, 1980); (c) that twins usually grew up in similar socioeconomic and cultural environments (Farber, 1981; Kamin, 1974; Rutter, 2006; Taylor, 1980); (d) methodological bias in favor of the recruitment of the most behaviorally similar segment of the total population of MZA pairs (Fancher, 1985; Farber, 1981; Kamin, 1974; Lerner, 2018; Rutter, 2006); (e) that cohort influences, in addition to twins’ common age and common sex, increase twins’ IQ correlations and behavioral resemblance in general (Kamin, 1974; Rose, 1982; Wyatt, 1993); (f) the potential unreliability of twins’ accounts of their degree of separation/contact and behavioral similarity (Joseph, 2015; Kamin, 1974; Kamin & Goldberger, 2002); (g) researcher confirmation bias (conscious or unconscious) in favor of genetic interpretations of the results (Joseph, 2015; Kamin, 1974); (h) problems with the validity of the tests administered to the twins (Kamin, 1974; Rutter, 2006; Taylor, 1980); (i) that the results might not apply (generalize) to the nontwin population (Cropanzano & James, 1990; Farber, 1981; Lerner, 2018); and (j) that MZAs will elicit more similar treatment from their social environments due to their substantial physical resemblance (Billings et al., 1992; Cropanzano & James, 1990; Ford, 1993).

 

In 1985, psychologist and historian Raymond Fancher described what he believed a “definitive” and “ideal” TRA study would look like:

A definitive study would have to employ twins who represent a genuinely random sample of the general population, and who have been randomly placed for adoption in a range of homes representative of the entire population. A definitive study would also have to demonstrate that its sample genuinely represents the full population of separated twins, and is not biased toward including only certain kinds of cases. Finally, in an ideal study all twins should have been completely separated from each other soon after birth, with no opportunity to communicate with each other or influence each other prior to their testing (Fancher, 1985, p. 165, emphasis in original).

 

The MISTRA did not come close to meeting this standard. As the study’s initiator and leader Thomas J. Bouchard Jr. recognized in relation to the published TRA studies, including his own,

Twins are not literally separated at birth, randomly assigned to homes, and evaluated as adults prior to any social contact. Such procedures would be necessary if a real experiment were being conducted, but such an experiment would be unethical. (Bouchard, 1993, p. 56)

 

Because a properly performed TRA study would be unethical, or is virtually impossible to accomplish, does not mean that science, and the general public informed by media accounts, must accept the results of a genetic study if it is based on a research design unable to control for potential environmental confounds.

 

I will now focus on the MISTRA IQ study, and on how the researchers arrived at their conclusions in favor of the “strong heritability” of IQ (Bouchard et al. 1990a, p. 223) – a conclusion I will challenge. The story I will tell about this famous study differs greatly from the story usually told by journalists, textbook authors, leading behavioral geneticists, and other authoritative authors and sources (references below).

 

Donc les critiques qui survivent sont :

1. Les données sont parfois mal catégorisées, on ne peut pas considérer que les jumeaux ont été élevés séparément quand ils ont été en contact (e.g. séparation plus d'un an après la naissance, contacts réguliers pendant l'enfance, au moins un des jumeaux est adopté par des membres de sa famille, les jumeaux ont vécu ensemble pendant au moins 12 mois...). C'est encore plus flou quand on considère que ce que les jumeaux racontent sur leur histoire personnelle n'est pas nécessairement fiable.
2. Des effets de cohorte qui expliquent la similarité entre jumeaux de manière au moins en partie non génétique : une paire de jumeaux partage le même âge, le même sexe, la même apparence (les gens beaux et laids sont traités différemment)... les placements pour adoption ne sont pas aléatoires et les jumeaux se retrouvent souvent dans des environnement socio-culturels similaires. Plus fondamentalement, même séparés à la naissance, les jumeaux partagent un environnement pré-natal.
3. Un biais des chercheurs qui ont tendance à préférer recruter dans les populations de jumeaux les plus semblables (aucune idée de comment ils feraient ça mais il y a plusieurs référence si vous êtes curieux), et qui auraient aussi un biais de confirmation vers l'explication génétique (ça ressemble à de l'ad hominem à ce point mais bon).
4. Des problèmes avec la validité des tests (j'avoue avoir un peu la flemme de regarder ça dans le détail, en gros l'histoire est qu'on présume que les effets des gènes sont indépendants, sans interaction entre gène et environnement ou entre gènes).
5. On ne sait pas dans quelle mesure les éventuels résultats sont généralisables à une population de non jumeaux.

On peut imaginer une étude "idéale" dont la méthodologie prendrait en compte la majorité de ces points, malheureusement une telle étude serait éthiquement discutable et pratiquement impossible. Vous aurez compris que cet article récent est lui aussi à charge et il enchaîne sur du méthodologisme classique pour dire que tout le monde fait de la merde. Bref.

Est-ce que ça veut dire que toute cette recherche est à jeter par la fenêtre comme par exemple celle sur les "biais implicites" ? Je ne sais pas, je ne pense pas. Au minimum on peut dire qu'il y a énormément de papiers qui sortent (cherchez "twin studies" sur google scholar) sans que les auteurs aient forcément conscience des limitations du paradigme et fassent au moins un effort pour les mitiger.

 

 

Voilà mon analyse superficielle d'un article. J'en ai relevé deux autres intéressants (likez et abonnez-vous à ma chaîne si vous voulez en savoir plus) :

 

Feldman, M. W., & Ramachandran, S. (2018). Missing compared to what? Revisiting heritability, genes and culture. Philosophical Transactions of the Royal Society B: Biological Sciences, 373(1743), 20170064.

Quote

Standard models for the determination of phenotypes from genes are grounded in simple assumptions that are inherent in the modern evolutionary synthesis (MES), which was developed in the 1930s, 1940s and 1950s. The MES was framed in the context of Mendelian genetic transmission enhanced by the Fisherian view of the way discretely inherited genes determine continuously quantitative phenotypes. The statistical models that are used to estimate and interpret genetic contributions to human phenotypes—including behavioural traits—are constructed within the framework of the MES. Variance analysis constitutes the main tool and is used under this framework to characterize genetic inheritance, and hence determination of phenotypes. In this essay, we show that cultural inheritance, when incorporated into models for the determination of phenotypes, can sharply reduce estimates of the genetic contribution to these phenotypes. Recognition of the importance of non-genetic transmission of many human traits is becoming ever more necessary to prevent regression to the debates of the 1970s and 1980s concerning policies based on genetic determination of complex human phenotypes.

 

Moore, D. S., & Shenk, D. (2017). The heritability fallacy. Wiley Interdisciplinary Reviews: Cognitive Science, 8(1-2), e1400.

Quote

The term 'heritability,' as it is used today in human behavioral genetics, is one of the most misleading in the history of science. Contrary to popular belief, the measurable heritability of a trait does not tell us how 'genetically inheritable' that trait is. Further, it does not inform us about what causes a trait, the relative influence of genes in the development of a trait, or the relative influence of the environment in the development of a trait. Because we already know that genetic factors have significant influence on the development of all human traits, measures of heritability are of little value, except in very rare cases. We, therefore, suggest that continued use of the term does enormous damage to the public understanding of how human beings develop their individual traits and identities.

[Pegase]

Très complet, merci Lancelot.

La vidéo revient aussi sur l'opposition entre généticiens du comportement et généticiens moléculaires en arguant que toutes les affirmations des premiers sont toujours devenues de plus en plus difficiles à prouver dans le temps (le fameux missing heritability problem).

 

Vous avez des sources sur cette question ? On m'a conseillé Robert Sapolsky.

[Adrian]

The heritability of IQ test performance I:What does IQ measure?

 

Citation

6.0 | Summary

• An IQ test score is a weighted average of scores across tests of memory, vocabulary, numeric reasoning, and general knowledge. A consistent observation from IQ test data is that individuals who do poorly on one test tend to do poorly on multiple tests – producing a correlation across scores known as the “positive manifold”. Motivated by these correlations, IQ is often summarized with a “general factor” (or g) score, which is simply a different re-weighted average of IQ subtest scores.
• Much research has gone into developing theories of IQ test correlation and the positive manifold. Theories are critical to understanding what the test is measuring, how to design accurate/unbiased tests, how to use tests to understand interventions, and how to draw broader conclusions about the mind. Common theories that can explain the positive manifold include:

• Bonds/sampling theory: Cognition is formed by a very large number of processes, with each IQ subtest sampling some subset of processes. The positive manifold is merely a statistical artifact of the incidental overlap between the processes across subtests.
• Dynamic mutualism: Cognition is formed by the “mutualist” interaction between multiple underlying processes where development of one process leads to growth in other processes. These relationships induce a positive manifold over time even though no general factor exists as a causal entity.
• g/Factor theory: Cognition is formed by the general factor itself (akin to a “mental energy”), which drives performance across all subtests in addition to some independent test-specific abilities. g theory has been expanded to include multiple factors or factor hierarchies.
• Process Overlap Theory: A synthesis of sampling and factor theories where subtests sample from processes that are either domain-specific (with three named domains) or domain-general. The positive manifold is an emergent property of the domain general process overlap but is not itself a causal entity.

• Five paradoxical findings regarding the measurement of IQ and g:

• The general factor weights (or “loadings”) of subtests are nearly perfectly correlated with the culturally-specificity of each subtest (e.g. higher for vocabulary, lower for numeric memory) (Kan et al. 2013). Thus a g score is merely an IQ score re-weighted by acculturation.
• The positive manifold increases with lower IQ, meaning that low IQ individuals tend to do poorly on all tests whereas higher IQ individuals tend to do well on only some tests. Paradoxically, the positive manifold also increases as children develop and decreases as adults decline. These paradoxical observations are incompatible with a single g-factor process across all individuals and likely necessitate a dynamic model.
• Multiple longitudinal studies have found that IQ is not associated with an increased rate of cognitive or academic growth in young age through adolescence (Larsen and Little 2023), nor with faster acquisition of job skills in adults (Schmidt et al. 1988), nor with the rate of cognitive decline in the elderly (Gow et al. 2011). This yields a third paradox: if g is a measurement of “general processing speed”, why is it not associated with faster learning (nor with slower cognitive decline)?
• Socioeconomic status (SES) is significantly associated with IQ gains: on average, children in low SES families started at a 6 IQ point deficit at age 2, and had a 15-17 IQ point deficit by age 16 (von Stumm and Plomin 2015). The effect of SES on academic achievement remained significant even when adjusting for future IQ measurements, indicating that SES can drive an environmental feedback loop between IQ and schooling. This yields a fourth paradox: if g is causal and largely independent of the shared environment, as is often claimed, why does the shared environment (SES) correlate with IQ gains while IQ does not?
• The Flynn Effect: IQ has increased an average of ~2 points per decade, with the largest gains in teenagers (Wongupparaj et al. 2023). The gains were not homogenous: increasing scores were observed on the more g loaded subtests in lower IQ individuals and decreasing scores were observed on less g loaded subtests in higher IQ individuals (Colom et al. 2023). The heterogenous increase in IQ suggests substantial, culturally induced changes acting on different processes. This yields a fifth paradox for g, as the underlying construct itself appears to be changing rapidly over time or else implies that the average individual born in the 19th century was severely mentally handicapped.
• Test-retest reliability of a general factor in the UK Biobank was high (r = 0.82) for a 30 day gap (Fawns-Ritchie and Deary 2020). Test ranking generally stabilizes in adolescence (r>0.7) (Tucker-Drob and Briley 2014) with moderate correlations (r = 0.45) observed from age 11 to age 90 after removing outliers (Deary, Pattie, and Starr 2013).
• There is meta-analytic evidence that IQ test results can be substantially impacted by motivation and the stronger the motivation the larger the effect (though studies have generally been limited and small) (Duckworth et al. 2011).

• Multiple lines of evidence – longitudinal measurements, cross-sectional model fitting, neurological, and interventional – refute a simple general factor theory of intelligence:

• Dynamic / mutualist models have been supported by cross-sectional and longitudinal studies, where performance in one cognitive domain is associated with improvement in other domains (Kievit, Hofman, and Nation 2019). Network models also often provide a better fit to IQ subtest data in cross-sectional studies (Kan et al. 2020). A recent large-scale genetic analysis revealed higher-order negative relationships between subtests, and a substantially different relationship between familial correlations and g loadings from that of a conventional factor model (Knyspel and Plomin 2024).
• Neurological measurements exhibit highly complex structure and do not support a single “neuro g” factor: structural data does not form a unidimensional latent factor mapping to IQ (Kievit et al. 2012) nor do structural correlations from different test batteries strongly overlap (Haier et al. 2009); network models generally fit the relationship between connectivity data and IQ tests best (Anderson and Barbey 2023; Soreq et al. 2021); and studies of focal brain injuries generally show local rather than general effects (Protzko and Colom 2021).
• One of very few theory-motivated experimental studies found unexpectedly large gains from mutualistic models: participants who trained on a diverse set of tasks had more substantial gains on a different specific task than participants who trained only on that task (Stine-Morrow et al. 2024). This preliminary finding highlights how experimental studies could be used to probe cognitive theories and produce surprising results.

• In sum: IQ scores clearly do not behave as a single latent process and are best seen as a bundle of processes with multiple sources of within-/between- individual and temporal heterogeneity. G-factor scores do not mitigate these issues and may in fact exacerbate them, as they are simply a reweighting of subtests to favor those with higher cultural specificity. While IQ scores may be a convenient data summarization technique, they also quickly become obsolete due to the Flynn Effect, are critically confounded by SES, and do not capture the process we are often most interested in: cognitive growth and decline. There is no reason to think that IQ scores are fundamentally more real or biological than Educational Attainment, they are simply an index of a different mix of processes which remains just as poorly understood.

 

[Paperasse]

il y a 41 minutes, Rincevent a dit :

il y a coévolution entre gènes et culture.

 

Un truc que je souhaitais évoquer sur le forum, sur cette question, c'est qu'on peut lire qu'Engels est le premier à avoir introduit la théorie de "coévolution gènes cultures" (dans son essai non terminé The Part Played by Labour in the Transition from Ape to Man, 1876).

 

Kangal, K. (2020). Engels’s emergentist dialectics :

Citation

Gould was particularly impressed by Engels’s view that the human “hand is not only the organ of labor, it is also the product of labor.… As humans learned to master their material surroundings, Engels argues, other skills were added to primitive hunting — agriculture, spinning, pottery, navigation, arts and sciences, law and politics." Elsewhere, Gould asserted that all human evolution stands and falls with gene-culture coevolution and “the best nineteenth-century case for gene-culture coevolution was made by Friedrich Engels in his remarkable essay of 1876."

 

Si c'est vrai, ça me semble un peu en contradiction avec cette idée d'associer le socialisme à la "tabula rasa"...

 

J'avoue que j'ai pas encore ultra creusé cette question. De ce que j'ai l'intuition, c'est que c'est un peu une sur-interprétation de considérer cet ouvrage comme l'origine de la "coévolution gènes cultures"

 

(je place cette remarque ici et pas dans le fil "Mes lectures du moment" pour pas partir en hors sujet et casser le débat sur le IQ)

[Rincevent]

il y a une heure, Paperasse a dit :

Gould

J'ai arrêté de lire là. 

[Adrian]

Twin Studies Exaggerate IQ Heritability

 

Citation

Heritability estimates are inflated by gene-environment correlation among other factors.


While twin/adoption studies had found that the heritability of IQ was around 80%, the largest GWAS analysis of intelligence, which examined the effect of more than nine million gene variants, found that only 2 to 5% of variation in IQ could be predicted from genes.1 Another high-quality GWAS found a heritability for cognitive ability of 14%. Whereas twin/adoption studies found that the heritability of IQ and height was quite similar, geneticist Sasha Gusev has shown, in a highly illuminating discussion of GWAS, that IQ is much more environmentally sensitive than height.
 

 

[Rincevent]

il y a 2 minutes, Adrian a dit :

Twin Studies Exaggerate IQ Heritability

Ok, j'allume le bat-@Lancelot-signal.

[Lancelot]

Lancelot a le regret de vous informer qu'il n'a pas le loisir ni particulièrement l'envie de lire tous les liens au pif vers des articles de blog balancés sans contexte comme une carte pokémon. Il vous invite cependant à lire son message quelques posts plus haut seulement où il s'intéresse précisément à la littérature critiquant les twin studies, et à revenir vers lui quand vous aurez des questions ou arguments précis.

[Bézoukhov]

T’as de la chance ça pourrait être une vidéo.

 

En substance le gus est un spécialiste des GWAS et dit qu’il y a sûrement quelque chose qui cloche dans les twin studies parce que les GWAS ne montrent pas d’aussi gros coefficients.

[Sloonz]

Discuté au 51e paragraphe de https://www.astralcodexten.com/p/links-for-november-2024

[Lancelot]

2 hours ago, Bézoukhov said:

T’as de la chance ça pourrait être une vidéo.

 

En substance le gus est un spécialiste des GWAS et dit qu’il y a sûrement quelque chose qui cloche dans les twin studies parce que les GWAS ne montrent pas d’aussi gros coefficients.

Et il a tout à fait le droit de penser ce qu'il veut.

[Bézoukhov]

Ce que j’en pense c’est que j’y connais rien en GWAS mais qu’avec la bonne base de données et ce genre de méthodes statistiques, je peux vous montrer presque ce que je veux.

 

(sauf qu’il y a une plus de deux sexes, on peut pas non plus faire n’importe quoi)

[Adrian]

 

 

 

 

 

 

 

Citation

Relative to most other animals, including primates, humans are unusually genetically homogenous (1, 71–73). Fewer than 1 in 1,000 nucleotide bases differ between any randomly chosen pair of humans (72). What genetic variation does exist is not structured into races. Lewontin (74) first reported that the proportion of genetic variation among socially defined human races is low, and suggested that racial taxonomy for our species is biologically meaningless, a conclusion supported by many subsequent studies (e.g., refs. 75–78). Approximately 93% of human genetic variation is found within populations, and only 4% among continents, with the remaining 2 to 3% among populations within continents (76). Most alleles are widely distributed around the world, with few (c. 7%) private to individual continents, and those typically at low frequency; thus there are no distinctive alleles present in all members of one region but absent from individuals outside the region (79). Even for complex traits affected by multiple loci, population genetic theory shows that “groups are not unduly likely to differ on traits that are determined by many loci, even when the loci influencing the trait would provide a sufficient basis for accurate classification” (80).

 

Within evolutionary biology the term “race” has a precise scientific meaning, broadly equivalent to “subspecies,” but human populations are not distinct enough to qualify as races. Subdivision is commonly quantified using a statistic called F_ST, which relates the genetic variation within and between populations. F_ST ranges from 0 (no population subdivision) to 1 (complete subdivision), with an F_ST exceeding 0.25 potentially indicating the existence of genetic subgroups (1). An authoritative estimate from the 1000 Genomes Project (81) of the global human F_ST was 0.052 to 0.083, revealing that the human population exhibits relatively little genetic subdivision; sharp genetic boundaries and distinct evolutionary lineages of “races” do not exist (1, 82). Rather, human biological diversity is clinal: It changes continuously with geographical separation, as groups merge into each other (83, 84). There may be discontinuities caused by geographic barriers (85), but these barriers are not insurmountable (10). As modern humans migrated from Africa, continuous contact and gene flow meant that they did not form subspecies (1, 86), but rather a “nested pattern of genetic structure inconsistent with the existence of independently evolving biological races” (87).

 

Humans who migrated to higher latitudes experienced a reduction in sunlight, leading to selection that favored lighter skin at several loci (10, 39, 88). However, the distribution and evolution of genes for skin color are not representative of the rest of the human genome, most of which offers little evidence that selection has played a dominant role, with random genetic drift and serial founder effects thought to be more important (79, 89). The genes underlying skin color do not provide a reliable index of genetic differentiation between groups (90, 91).

 

Edwards (92) claimed that Lewontin (74) had committed a “fallacy” by failing to consider correlations between genes, which he argued would allow individuals to be assigned to racial groups. Subsequent studies have established that large sets of loci can contain a great deal of information about population membership and permit ancestry inferences (76). However, it does not follow that Lewontin’s conclusions about race were fallacious (1, 93). This can be seen by considering the hypothetical case that all genetic variation is geographically continuous and nonclustered; geographical origin is informative but there are no biological races. This scenario is actually a reasonable approximation to reality. Most humans from the same geographic region are fractionally more similar to one another genetically than to individuals from a distant region. However, because of our history of migration and interbreeding, human genetic variation tends to be spatially distributed in a continuous fashion. If a fallacy existed, it was Edwards’ confounding geographical origin with race (17).

 

Another way to address these issues is to examine what genetic substructure does exist and ask whether it maps onto human races. While the mean genetic difference for two individuals from the same population is almost as large as that for two individuals chosen from any two populations (79), if enough loci are considered, humans can be organized into groups by genetic similarity. Methods exist for partitioning species into clusters of genetically similar individuals, and model-based clustering is a popular technique for quantifying the genetic ancestry of humans and other organisms (Box 1). The methods are generally applied to neutral genetic variation, since most DNA variants that differ in frequency between groups are neutral, functionally insignificant, and probably of little relevance to phenotypic differences between populations (94). For reliable assignment of individuals to continents, over a hundred genetic variants are required, and more for fine-grained population subdivision (91). This reasoning cannot be reversed to predict accurately the genotype of an individual from knowledge of their region of origin; knowing an individual’s continental ancestry only slightly improves the ability to predict their genotype (91).

 

Statistically estimated clusters using human DNA variants are inconsistent with socially defined races (Box 1). Even those willing, with minimal evidence, to assume that ancestry analyses support the existence of some human races, would be forced to conclude that “races” are not those implied by traits such as skin color or eye shape. Ancestry estimated from DNA variants, while itself an ambiguous concept (95), nonetheless provides a far more subtle and complex description of an individual’s genetic makeup than “race” (72, 90). No human populations are “pure” in a genetic sense; individuals do not fall neatly into one of the categories usually defined as “races,” and perceived boundaries between so-called “races” are arbitrary.

 

Et Concepts: race and genetic ancestry que j'avais déjà posté ailleurs.

[Rincevent]

il y a 12 minutes, Adrian a dit :

 

Etape 1 : cette idée est complètement à côté de la plaque, pas la peine de s'y intéresser.

Etape 2 : cette idée est dangereuse, il ne faut pas y toucher.

Etape 3 : cette idée est perverse, il faut largement l'amender.

Etape 4 : cette idée est mainstream, de toute façon on l'a toujours défendue.

 

Intéressant de voir que les questions de biodiversité humaine percolent peu à peu dans l'étape 4...

[Mathieu_D]

9 hours ago, Rincevent said:

Etape 1 : cette idée est complètement à côté de la plaque, pas la peine de s'y intéresser.

Etape 2 : cette idée est dangereuse, il ne faut pas y toucher.

Etape 3 : cette idée est perverse, il faut largement l'amender.

Etape 4 : cette idée est mainstream, de toute façon on l'a toujours défendue.

 

Intéressant de voir que les questions de biodiversité humaine percolent peu à peu dans l'étape 4...

Heu on serait plutôt à l'étape 5, l'idée est générée par l'IA de legorafi et personne ne sait si c'est du lard ou du cochon et à ce point peu importe.

[Bézoukhov]

J'ai rien compris à la phrase. L'impression d'être dans un sketche des inconnus.