Flynn effect and its reversal are both environmentally caused

Bratsberg, Bernt; Røgeberg, Ole

doi:10.1073/pnas.1718793115

Cited by 136 publications

(89 citation statements)

References 20 publications

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“…These studies suggest that there has been a transition in the relationship between intelligence and fertility over time, from no clear gradient among cohorts born in the first half of the twentieth century, to a small to moderate negative gradient (i.e. higher intelligence, lower fertility) for cohorts born in the second half of the twentieth century [6,18,20,21], though a minority of studies have reported positive gradients [17,22,23]. In general, studies have reported a steeper negative gradient for women than for men (e.g.…”

Section: (A) Previous Research On Intelligence and Fertilitymentioning

confidence: 99%

Cognitive ability and fertility among Swedish men born 1951–1967: evidence from military conscription registers

Kolk

Barclay

2019

Proc. R. Soc. B.

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We examine the relationship between cognitive ability and childbearing patterns in contemporary Sweden using administrative register data. The topic has a long history in the social sciences and has been the topic of a large number of studies, many reporting a negative gradient between intelligence and fertility. We link fertility histories to military conscription tests with intelligence scores for all Swedish men born 1951-1967. We find a positive relationship between intelligence scores and fertility, and this pattern is consistent across the cohorts we study. The relationship is most pronounced for the transition to a first child, and men with the lowest categories of IQ scores have the fewest children. Using fixed effects models, we additionally control for all factors that are shared by siblings, and after such adjustments, we find a stronger positive relationship between IQ and fertility. Furthermore, we find a positive gradient within groups at different levels of education. Compositional differences of this kind are therefore not responsible for the positive gradient we observe-instead, the relationship is even stronger after controlling for both educational careers and parental background factors. In our models where we compare brothers to one another, we find that, relative to men with IQ 100, the group with the lowest category of cognitive ability have 0.56 fewer children, and men with the highest category have 0.09 more children.

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Section: (A) Previous Research On Intelligence and Fertilitymentioning

confidence: 99%

Cognitive ability and fertility among Swedish men born 1951–1967: evidence from military conscription registers

Kolk

Barclay

2019

Proc. R. Soc. B.

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“…The combined contribution of all of these genomic variants to any group level difference in a complex human trait is predicted to be small, possibly spurious, and largely dependent on the environment according to population genetic theory (Rosenberg et al, 2018). Empirically, we also know that intergenerational scores on IQ tests have changed over time because of improvements in the human environment (Bratsberg & Rogeberg, 2018;Flynn, 1999) and the association of IQ with genetic factors depends heavily on environmental factors (Devlin, Daniels, & Roeder, 1997;Flynn, 1999;Turkheimer, Haley, Waldron, D'Onofrio, & Gottesman, 2003). To claim that racial inequality in education is immutable because of genetics is no less of distortion of scientific knowledge today than it was in the 1970s or 1930s.…”

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confidence: 99%

Toward a more humane genetics education: Learning about the social and quantitative complexities of human genetic variation research could reduce racial bias in adolescent and adult populations

Donovan

Semmens

Keck³

et al. 2019

Science Education

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When people are exposed to information that leads them to overestimate the actual amount of genetic difference between racial groups, it can augment their racial biases. However, there is apparently no research that explores if the reverse is possible. Does teaching adolescents scientifically accurate information about genetic variation within and between US census races reduce their racial biases? We randomized 8th and 9th grade students (n = 166) into separate classrooms to learn for an entire week either about the topics of (a) human genetic variation or (b) climate variation. In a cross‐over randomized trial with clustering, we demonstrate that when students learn about genetic variation within and between racial groups it significantly changes their perceptions of human genetic variation, thereby causing a significant decrease in their scores on instruments assessing cognitive forms of prejudice. We then replicate these findings in two computer‐based randomized controlled trials, one with adults (n = 176) and another with biology students (n = 721, 9th–12th graders). These results indicate that teaching about human variation in the domain of genetics has potentially powerful effects on social cognition during adolescence. In turn, we argue that learning about the social and quantitative complexities of human genetic variation research could prepare students to become informed participants in a society where human genetics is invoked as a rationale in sociopolitical debates.

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“…There is no consensus regarding the cause of the Flynn effect, but given the recent and rapid increase, genetic explanations are unlikely. Common hypotheses include increases in test familiarity, improvements in education, sophistication of the technological and media environment, better nutrition, decreasing family size, and increased out-breeding or 'hybrid vigor' (Bratsberg and Rogeberg 2018;Clark, Lawlor-Savage, and Goghari 2016;Nisbett et al 2012;Pietschnig and Voracek 2015; Trahan et al 2014;Johnson 2006). Flynn (2007) and Greenfield (1998; suggest that the effect is caused by a rapid worldwide increase of cultural practices, technologies, and environments that promote abstract cognitive processing as opposed to more traditional forms of concrete, pragmatic thinking.…”

Section: The Flynn Effectmentioning

confidence: 99%

Cultural Evolution of Genetic Heritability

Uchiyama

Spicer

Muthukrishna

2020

Preprint

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Behavioral genetics and cultural evolution have both revolutionized our understanding of human behavior, but largely independently of each other. Here we reconcile these two fields using a dual inheritance approach, which offers a more nuanced understanding of the interaction between genes and culture, and a resolution to several long-standing puzzles. For example, by neglecting how human environments are extensively shaped by cultural dynamics, behavioral genetic approaches systematically inflate heritability estimates and thereby overestimate the genetic basis of human behavior. A WEIRD (Western, educated, industrialized, rich, democratic) gene problem obscures this inflation. Considering both genetic and cultural evolutionary forces, heritability scores become less a property of a trait and more a moving target that responds to cultural and social changes. Ignoring cultural evolutionary forces leads to an over-simplified model of gene-to-phenotype causality. When cumulative culture functionally overlaps with genes, genetic effects become masked, or even reversed, and the causal effect of an identified gene is confounded with features of the cultural environment, specific to a particular society at a particular time. This framework helps explain why it is easier to discover genes for deficiencies than genes for abilities. With this framework, we predict the ways in which heritability should differ between societies, between socioeconomic levels within some societies but not others, and over the life course. An integrated cultural evolutionary behavioral genetics cuts through the nature–nurture debate and elucidates controversial topics such as general intelligence.

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Flynn effect and its reversal are both environmentally caused

Cited by 136 publications

References 20 publications

Cognitive ability and fertility among Swedish men born 1951–1967: evidence from military conscription registers

Cognitive ability and fertility among Swedish men born 1951–1967: evidence from military conscription registers

Toward a more humane genetics education: Learning about the social and quantitative complexities of human genetic variation research could reduce racial bias in adolescent and adult populations

Cultural Evolution of Genetic Heritability

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