Special Issue "Beyond Thirty Years of Research on Race Differences in Cognitive Ability"

A special issue of Psych (ISSN 2624-8611).

Deadline for manuscript submissions: 15 July 2019

Special Issue Editor

Guest Editor
Prof. Bryan J Pesta

Department of Management, Cleveland State University, 2121 Euclid Ave. BU 327, Cleveland, OH 44115, USA
Website | E-Mail
Interests: intelligence; IQ; discrimination law; individual differences; group differences; religiosity and IQ; testing; selection; cognition, cognitive psychology; human resource management

Special Issue Information

Dear Colleagues,

Fully 13 years have passed since Rushton and Jensen (2005) published their review of race differences in cognitive ability. The article now has over 500 citations. Rushton and Jensen’s (2005) work was impactful, partly because it carefully pitted culture-only versus hereditation models of the cause of race differences in intelligence. The authors were also thorough (the article is 60 pages long) in that they reviewed literature across ten “categories of evidence” regarding which model was possibly true. Ultimately, Rushton and Jensen (2005) concluded that “some genetic component [exists] in Black–White differences in mean IQ.”

Were they correct? What newer research has or will come to bear on this question? The special issue seeks high-quality scientific contributions regarding either Rushton and Jensen’s (2005) overall conclusion, or any of the ten categories of evidence they reviewed. Multiple perspectives are welcome. So too are reviews, new empirical evidence on the question(s), and articles that expand the scope beyond just Black / White comparisons. The contributions may focus on individuals as the unit of analysis, or feature aggregate-level (e.g., nations, regions, states) data.

The question is critically important because IQ is arguably the most powerful variable in social science. As such, group differences on IQ correlate with group differences on a host of variables (e.g., education, income, health, crime) that together seem to comprise human well-being. Without understanding the source of group-mean differences, we cannot make progress toward maximizing human well-being for everyone.

The ten categories of evidence include:

  • The worldwide distribution of test scores,
  • The g factor of mental ability,
  • Heritability,
  • Brain size and cognitive ability,
  • Transracial adoption
  • Racial admixture
  • regression
  • related life-history traits
  • human origins research
  • hypothesized environmental variables

Prof. Bryan J Pesta
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Psych is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) is waived for well-prepared manuscripts submitted to this issue. Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Intelligence
  • Group differences
  • Race
  • Ethnicity
  • Nature / Nurture
  • Well-being

Published Papers (12 papers)

View options order results:
result details:
Displaying articles 1-12
Export citation of selected articles as:

Editorial

Jump to: Research, Review, Other

Open AccessEditorial
A Conversation with Michael A. Woodley of Menie, Yr.
Psych 2019, 1(1), 207-219; https://doi.org/10.3390/psych1010015
Received: 22 April 2019 / Accepted: 5 May 2019 / Published: 9 May 2019
PDF Full-text (202 KB) | HTML Full-text | XML Full-text
Abstract
Michael Anthony Woodley of Menie, Yr (Younger), is a British ecologist and evolutionary psychologist, whose research on secular trends in dierent aspects of human intelligence has earned him considerable notability.[...] Full article
Open AccessEditorial
Reflections on Sixty-Eight Years of Research on Race and Intelligence
Psych 2019, 1(1), 123-131; https://doi.org/10.3390/psych1010009
Received: 1 April 2019 / Revised: 16 April 2019 / Accepted: 16 April 2019 / Published: 24 April 2019
PDF Full-text (212 KB) | HTML Full-text | XML Full-text
Abstract
I first encountered the question of race and intelligence sixty-eight years ago [...] Full article

Research

Jump to: Editorial, Review, Other

Open AccessArticle
Filling in the Gaps: The Association between Intelligence and Both Color and Parent-Reported Ancestry in the National Longitudinal Survey of Youth 1997
Psych 2019, 1(1), 240-261; https://doi.org/10.3390/psych1010017 (registering DOI)
Received: 9 April 2019 / Revised: 19 May 2019 / Accepted: 20 May 2019 / Published: 22 May 2019
PDF Full-text (811 KB) | XML Full-text
Abstract
Little research has dealt with intragroup ancestry-related differences in intelligence in Black and White Americans. To help fill this gap, we examined the association between intelligence and both color and parent-reported ancestry using the NLSY97. We used a nationally-representative sample, a multidimensional measure [...] Read more.
Little research has dealt with intragroup ancestry-related differences in intelligence in Black and White Americans. To help fill this gap, we examined the association between intelligence and both color and parent-reported ancestry using the NLSY97. We used a nationally-representative sample, a multidimensional measure of cognitive ability, and a sibling design. We found that African ancestry was negatively correlated with general mental ability scores among Whites (r = −0.038, N = 3603; corrected for attenuation, rc = −0.245). In contrast, the correlation between ability and parent-reported European ancestry was positive among Blacks (r = 0.137, N = 1788; rc = 0.344). Among Blacks, the correlation with darker skin color, an index of African ancestry, was negative (r = −0.112, N = 1455). These results remained with conspicuous controls. Among Blacks, both color and parent-reported European ancestry had independent effects on general cognitive ability (color: β = −0.104; ancestry: β = 0.118; N = 1445). These associations were more pronounced on g-loaded subtests, indicating a Jensen Effect for both color and ancestry (rs = 0.679 to 0.850). When we decomposed the color results for the African ancestry sample between and within families, we found an association between families, between singletons (β = −0.153; N = 814), and between full sibling pairs (β = −0.176; N = 225). However, we found no association between full siblings (β = 0.027; N = 225). Differential regression to the mean results indicated that the factors causing the mean group difference acted across the cognitive spectrum, with high-scoring African Americans no less affected than low-scoring ones. We tested for measurement invariance and found that strict factorial invariance was tenable. We then found that the weak version of Spearman’s hypothesis was tenable while the strong and contra versions were not. The results imply that the observed cognitive differences are primarily due to differences in g and that the Black-White mean difference is attributable to the same factors that cause differences within both groups. Further examination revealed comparable intraclass correlations and absolute differences for Black and White full siblings. This implied that the non-shared environmental variance components were similar in magnitude for both Blacks and Whites. Full article
Open AccessArticle
Race as Social Construct
Psych 2019, 1(1), 139-165; https://doi.org/10.3390/psych1010011
Received: 15 March 2019 / Revised: 24 April 2019 / Accepted: 25 April 2019 / Published: 29 April 2019
PDF Full-text (1353 KB) | HTML Full-text | XML Full-text
Abstract
It is often claimed that race is a social construct and that scientists studying race differences are disruptive racists. The recent April 2018 “Race Issue” of the widely distributed National Geographic Magazine (NG) provided its millions of readers with a particularly illustrative example [...] Read more.
It is often claimed that race is a social construct and that scientists studying race differences are disruptive racists. The recent April 2018 “Race Issue” of the widely distributed National Geographic Magazine (NG) provided its millions of readers with a particularly illustrative example of this position. As discussions of race issues often recur, in both scientific and lay literature, stir considerable polemics, and have political, societal and human implications, we found it of both scientific and general interest to identify and dissect the following partly overlapping key contentions of the NG race issue magazine: (1) Samuel Morton’s studies of brain size is reprehensible racism (2) Race does not relate to geographic location, (3) Races do not exist as we are all equals and Africans, (4) Admixture and displacement erase race differences as soon as they appear, and (5) Race is only skin color deep. Also examined is the claim that Race does not matter. When analyzed within syllogistic formalism, each of the claims is found theoretically and empirically unsustainable, as Morton’s continuously evolving race position is misrepresented, race relates significantly to geography, we are far from equals, races have definitely not been erased, and race, whether self-reported or defined by ancestry, lineage, ecotype, species, or genes, is much more than skin color deep. Race matters vitally for people and societies. We conclude that important research on existing population differences is hurt when widely respected institutions such as NG mobilize their full authority in a massively circulated attempt to betray its scientific and public readership by systematically misrepresenting historical sources and scientific positions, shaming past scientists, and by selectively suppressing unwanted or unacceptable results–acts included as examples of academic fraud by the National Academy of Sciences (US, 1986). Any unqualified a priori denial of the formative evolutionary aspects of individual and population differences threatens to impede the recent promising research on effects of genome wide allelic associations, which would lames us in the vital quest to develop rational solutions to associated globally pressing societal problems. Full article
Figures

Figure 1

Open AccessArticle
The Intelligence of Biracial Children of U.S. Servicemen in Northeast Asia: Results from Japan
Psych 2019, 1(1), 132-138; https://doi.org/10.3390/psych1010010
Received: 11 April 2019 / Revised: 16 April 2019 / Accepted: 17 April 2019 / Published: 24 April 2019
PDF Full-text (217 KB) | HTML Full-text | XML Full-text
Abstract
The IQ averages of biracial children have long been of interest to intelligence researchers for clarifying the causes of group differences in intelligence. We carried out a search for IQ test results of biracial children fathered by U.S. servicemen after World War 2 [...] Read more.
The IQ averages of biracial children have long been of interest to intelligence researchers for clarifying the causes of group differences in intelligence. We carried out a search for IQ test results of biracial children fathered by U.S. servicemen after World War 2 and indigenous Asian women in northeast Asian countries (Japan, Korea, China). We were able to locate a report from Japan from a foster home (n = 28–48 biracial children across tests). Results showed that there was only a minuscule IQ gap (<1 IQ) between children of Black–Japanese and White–Japanese parents. However, interpretation of the results is difficult owing to the very small sample size, the non-representative sample, and unknown patterns of assortative mating. We suggest possible avenues for future research. Full article
Open AccessArticle
Evidence for Recent Polygenic Selection on Educational Attainment and Intelligence Inferred from Gwas Hits: A Replication of Previous Findings Using Recent Data
Psych 2019, 1(1), 55-75; https://doi.org/10.3390/psych1010005
Received: 22 February 2019 / Revised: 23 March 2019 / Accepted: 26 March 2019 / Published: 28 March 2019
Cited by 1 | PDF Full-text (527 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Genetic variants identified by three large genome-wide association studies (GWAS) of educational attainment (EA) were used to test a polygenic selection model. Weighted and unweighted polygenic scores (PGS) were calculated and compared across populations using data from the 1000 Genomes (n = 26), [...] Read more.
Genetic variants identified by three large genome-wide association studies (GWAS) of educational attainment (EA) were used to test a polygenic selection model. Weighted and unweighted polygenic scores (PGS) were calculated and compared across populations using data from the 1000 Genomes (n = 26), HGDP-CEPH (n = 52) and gnomAD (n = 8) datasets. The PGS from the largest EA GWAS was highly correlated to two previously published PGSs (r = 0.96–0.97, N = 26). These factors are both highly predictive of average population IQ (r = 0.9, N = 23) and Learning index (r = 0.8, N = 22) and are robust to tests of spatial autocorrelation. Monte Carlo simulations yielded highly significant p values. In the gnomAD samples, the correlation between PGS and IQ was almost perfect (r = 0.98, N = 8), and ANOVA showed significant population differences in allele frequencies with positive effect. Socioeconomic variables slightly improved the prediction accuracy of the model (from 78–80% to 85–89%), but the PGS explained twice as much of the variance in IQ compared to socioeconomic variables. In both 1000 Genomes and gnomAD, there was a weak trend for lower GWAS significance SNPs to be less predictive of population IQ. Additionally, a subset of SNPs were found in the HGDP-CEPH sample (N = 127). The analysis of this sample yielded a positive correlation with latitude and a low negative correlation with distance from East Africa. This study provides robust results after accounting for spatial autocorrelation with Fst distances and random noise via an empirical Monte Carlo simulation using null SNPs. Full article
Figures

Figure 1

Open AccessArticle
The Effect of Biracial Status and Color on Crystallized Intelligence in the U.S.-Born African–European American Population
Psych 2019, 1(1), 44-54; https://doi.org/10.3390/psych1010004
Received: 2 January 2019 / Revised: 1 March 2019 / Accepted: 5 March 2019 / Published: 7 March 2019
PDF Full-text (218 KB) | HTML Full-text | XML Full-text
Abstract
The relationship between biracial status, color, and crystallized intelligence was examined in a nationally representative sample of adult Black and White Americans. First, it was found that self-identifying biracial individuals, who were found to be intermediate in color and in self-reported ancestry, had [...] Read more.
The relationship between biracial status, color, and crystallized intelligence was examined in a nationally representative sample of adult Black and White Americans. First, it was found that self-identifying biracial individuals, who were found to be intermediate in color and in self-reported ancestry, had intermediate levels of crystallized intelligence relative to self-identifying White (mostly European ancestry) and Black (mostly sub-Saharan African ancestry) Americans. The results were transformed to an IQ scale: White (M = 100.00, N = 7569), primarily White–biracial (M = 96.07, N = 43, primarily Black–biracial (M = 94.14 N = 50), and Black (M = 89.81, N = 1381). Next, among self-identifying African Americans, a statistically significant negative correlation of r = −0.102 (N = 637) was found between interviewer-rated darker facial color and vocabulary scores. After correction for the reliability of the measures, this correlation increased to r = −0.21. Corrections for the validity of color as an index of African ancestry would raise this correlation to around r = −0.48. This association among self-identifying African Americans was not accounted for by confounding factors, such as region of residence and interviewer race, or by parental socioeconomic status and individual educational attainment. In the multivariate models, the standardized betas for color and crystallized intelligence among African Americans ranged from β = −0.112 to β = −0.142. Based on the coefficients from the multivariate analysis, it was further found that cognitive ability was a significant mediator in the context of color and education, while education was not in the context of color and cognitive ability. It is concluded that these results further substantiate the statistical relation between intelligence and biogeographic ancestry in African and European American populations. Full article
Open AccessArticle
Spearman’s Hypothesis Tested Comparing 47 Regions of Japan Using a Sample of 18 Million Children
Psych 2019, 1(1), 26-34; https://doi.org/10.3390/psych1010002
Received: 20 December 2018 / Revised: 18 January 2019 / Accepted: 1 February 2019 / Published: 11 February 2019
PDF Full-text (649 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Many groups differ in their mean intelligence score. Spearman’s hypothesis states that the differences are a function of cognitive complexity. There tend to be large differences on subtests of high cognitive complexity and small differences on subtests of low cognitive complexity. Spearman’s hypothesis [...] Read more.
Many groups differ in their mean intelligence score. Spearman’s hypothesis states that the differences are a function of cognitive complexity. There tend to be large differences on subtests of high cognitive complexity and small differences on subtests of low cognitive complexity. Spearman’s hypothesis has been supported by a large number of studies. Can Spearman’s hypothesis be generalized to regions of a country, where these regions differ in mean intelligence? We utilized data from 86 different cognitive tests from all 47 Japanese prefectures and correlated the g loadings of 86 subtests with standardized differences on the same subtests. Spearman’s hypothesis was clearly supported: the biggest differences between the regions were on the tests that were of the greatest complexity, meaning that Spearman’s hypothesis may be generalizable from groups to regions. In Japan, g loadings offer a better explanation of group differences in intelligence than cultural differences. Future research should explore whether Spearman’s hypothesis is also supported for differences between regions of other countries. Full article
Figures

Graphical abstract

Open AccessArticle
Biogeographic Ancestry, Cognitive Ability and Socioeconomic Outcomes
Psych 2019, 1(1), 1-25; https://doi.org/10.3390/psych1010001
Received: 12 November 2018 / Revised: 20 December 2018 / Accepted: 20 December 2018 / Published: 10 January 2019
Cited by 2 | PDF Full-text (1716 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The cause(s) of ubiquitous cognitive differences between American self-identified racial/ethnic groups (SIREs) is uncertain. Evolutionary-genetic models posit that ancestral genetic selection pressures are the ultimate source of these differences. Conversely, sociological models posit that these differences result from racial discrimination. To examine predictions [...] Read more.
The cause(s) of ubiquitous cognitive differences between American self-identified racial/ethnic groups (SIREs) is uncertain. Evolutionary-genetic models posit that ancestral genetic selection pressures are the ultimate source of these differences. Conversely, sociological models posit that these differences result from racial discrimination. To examine predictions based on these models, we conducted a global admixture analysis using data from the Pediatric Imaging, Neurocognition, and Genetics Study (PING; N = 1,369 American children). Specifically, we employed a standard methodology of genetic epidemiology to determine whether genetic ancestry significantly predicts cognitive ability, independent of SIRE. In regression models using four different codings for SIRE as a covariate, we found incremental relationships between genetic ancestry and both general cognitive ability and parental socioeconomic status (SES). The relationships between global ancestry and cognitive ability were partially attenuated when parental SES was added as a predictor and when cognitive ability was the outcome. Moreover, these associations generally held when subgroups were analyzed separately. Our results are congruent with evolutionary-genetic models of group differences and with certain environmental models that mimic the predictions of evolutionary-genetic ones. Implications for research on race/ethnic differences in the Americas are discussed, as are methods for further exploring the matter. Full article
Figures

Figure 1

Review

Jump to: Editorial, Research, Other

Open AccessReview
A Meta-Analysis of Spearman’s Hypothesis Tested on Latin-American Hispanics, Including a New Way to Correct for Imperfectly Measuring the Construct of g
Psych 2019, 1(1), 101-122; https://doi.org/10.3390/psych1010008
Received: 9 March 2019 / Revised: 6 April 2019 / Accepted: 12 April 2019 / Published: 18 April 2019
PDF Full-text (830 KB) | HTML Full-text | XML Full-text
Abstract
Spearman’s hypothesis states that the difference in intelligence between groups is a function of the g loadings of the subtests, where larger differences are found on tests with higher g loadings. This finding has consistently been supported on various groups. In this study [...] Read more.
Spearman’s hypothesis states that the difference in intelligence between groups is a function of the g loadings of the subtests, where larger differences are found on tests with higher g loadings. This finding has consistently been supported on various groups. In this study we look at samples of Latin-American Hispanics in comparison to Whites. We carried out a meta-analysis based on 14 data points and a total of 16,813 Latin-American Hispanics, including a new way to correct for imperfectly measuring the construct of g. Spearman’s hypothesis was strongly supported with a mean r of 0.63. After correction for various statistical artifacts this value became rho = 0.91. Therefore, we conclude that Spearman’s hypothesis also holds true for White/Latin-American Hispanic differences. Full article
Figures

Figure 1

Other

Open AccessEssay
The Original Industrial Revolution. Did Cold Winters Select for Cognitive Ability?
Psych 2019, 1(1), 166-181; https://doi.org/10.3390/psych1010012
Received: 18 March 2019 / Revised: 15 April 2019 / Accepted: 15 April 2019 / Published: 2 May 2019
PDF Full-text (628 KB) | Supplementary Files
Abstract
Rushton and Jensen argued that cognitive ability differs between human populations. But why are such differences expectable? Their answer: as modern humans spread out of Africa and into northern Eurasia, they entered colder and more seasonal climates that selected for the ability to [...] Read more.
Rushton and Jensen argued that cognitive ability differs between human populations. But why are such differences expectable? Their answer: as modern humans spread out of Africa and into northern Eurasia, they entered colder and more seasonal climates that selected for the ability to plan ahead, in order to store food, make clothes, and build shelters for winter. This cold winter theory is supported by research on Paleolithic humans and recent hunter-gatherers. Tools become more diverse and complex as effective temperature decreases, apparently because food has to be obtained during limited periods and over large areas. There is also more storage of food and fuel and greater use of untended traps and snares. Finally, shelters have to be sturdier, and clothing more cold-resistant. The resulting cognitive demands are met primarily by women because the lack of opportunities for food gathering pushes them into more cognitively demanding tasks, like garment making, needlework, weaving, leatherworking, pottery, and kiln operation. The northern tier of Paleolithic Eurasia thus produced the "Original Industrial Revolution"—an explosion of creativity that preadapted its inhabitants for later developments, i.e., farming, more complex technology and social organization, and an increasingly future-oriented culture. Over time, these humans would spread south, replacing earlier populations that could less easily exploit the possibilities of the new cultural environment. As this environment developed further, it selected for further increases in cognitive ability. Indeed, mean intelligence seems to have risen during recorded history at temperate latitudes in Europe and East Asia. There is thus no unified theory for the evolution of human intelligence. A key stage was adaptation to cold winters during the Paleolithic, but much happened later. Full article
Open AccessCommentary
Reservations about Rushton
Psych 2019, 1(1), 35-43; https://doi.org/10.3390/psych1010003
Received: 20 December 2018 / Revised: 21 January 2019 / Accepted: 1 February 2019 / Published: 11 February 2019
Cited by 1 | PDF Full-text (203 KB) | HTML Full-text | XML Full-text
Abstract
Rushton believed not only that East Asians, whites, and blacks could be ranked in that order for desirable traits but also that the black/white IQ gap is predominantly genetic in origin. Concerning the first, he relied on the “ice ages hypothesis”to show that [...] Read more.
Rushton believed not only that East Asians, whites, and blacks could be ranked in that order for desirable traits but also that the black/white IQ gap is predominantly genetic in origin. Concerning the first, he relied on the “ice ages hypothesis”to show that the evolutionary history of the three races had varied as East Asians were subjected to the most demanding environment (north of the Himalayas), whites to the next most demanding (north of the Alps), and blacks to the least demanding (Africa). As to the second, he appealed to arguments based on the method of correlated vectors (Jensen effects) and regression to the mean. To assess his contribution I argue: (1) That the racial ranking for desirable traits is not as tidy as it seems; (2) That the ice ages hypothesis has been falsified; (3) That the black/white Q gap is more likely to be environmental, with black American subculture as the culprit; and (4) That appeals to correlated vectors and regression cannot disentangle genetic and environmental causes. Full article

Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Weak Genes or Strong Germs?
Chanda Chrisala, Stanford University
Abstract: Presents an alternative biological hypothesis to the Jensenian genetic hypothesis for Black-White IQ differences in America. Looks at some of the most recent epidemiological findings on infections that were previously not known to directly lower cognitive ability, and that happen to be much more prevalent in African Americans than European Americans. This pathogenic hypothesis invites serious consideration to replace Jensen’s default hypothesis as it appears to also predict other phenomena that have persistently defied simple hereditarian models.

A test of the UV radiation-intelligence connection across 3064 counties of the United States
Federico Leon, Universidad San Ignacio de Loyola
John Fuerst, Ulster Institute for Social Research
Abstract: Absolute latitude is associated with both well-being and IQ, but the nature of their relationship is ambiguous. Some have proposed evolutionary hypotheses. An alternative is the UV radiation hypothesis which proposes that contemporaneous UV (ultraviolet) radiation effects cognitive ability through a number of physiological and behavioral pathways. This study applies path modeling to data on 3064 counties of the United States of America to further test the UV-IQ visa vis racial composition models. The evidence for the UV hypothesis is summarized and discussed in light of these results.

Modeling the Spearman's hypothesis using MGCFA: The Woodcock Johnson dataset
Meng Hu, Independent Researcher
Michael Woodley, Vrije Universiteit Brussel, Center Leo Apostel for Interdisciplinary Research, Belgium
Abstract: There has been a good deal of research on Spearman's hypothesis with regard to Black-White differences in tests of cognitive ability. Most of the research has relied on Jensen's Method of Correlated Vectors (Jensen, 1998). This method, however, is incapable of rigorously testing competing models that do not involve group differences in g (Dolan, 2000, Dolan & Hamaker, 2001). The purpose of the present paper is to test Spearman's hypothesis using Multi-Group Confirmatory Factor Analysis applied to three waves of Woodcock-Johnson standardization data. First, using Jensen's MCV, it is found, for all three standardization waves, that there is a Jensen effect, i.e., positive correlation between the subtests' g-loadings and the Black-White differences. Secondly, while measurement invariance (MI) was generally found to hold, results from MGCFA using either the high-order-factor or the bi-factor model approach were unclear, indicating a lack of discriminatory ability. Recommendations for future research on Spearman’s hypothesis are made.

Mixed race, intermediate results? A meta-analysis of over a century of studies on racial admixture and cognitive ability
Richard Lynn
John Fuerst, Ulster Institute for Social Research
Abstract:  Whether racial admixture is associated with cognitive ability in admixed populations has figured prominently in debates on the etiology of group differences. To evaluate this issue, we review over 100 years of research looking at the association between genetic, genealogical, phenotypic, and cultural indexes of admixture and intelligence or academic achievement scores. We focus on the following major biogeographic groups from six continental regions: Europeans, North East Asians, American Indian, Sub-Saharan Africans, Pacific Islander, and Australian Aborigines. Results are discussed in light of ongoing debates regarding the cause of ethnic group differences in measured cognitive ability.

Rushton’s Hypothesis Revisited:The Biogeography of Human Diversity in Life History Strategy
Aurelio José Figueredo1, Steven C Hertler2, & Mateo Peñaherrera-Aguirre1
1University of Arizona; 2College of New Rochelle
Abstract:
Rushton (1985) advanced a controversial theory relating “race” to life history strategy in human populations. The essence of the hypothesis was as follows: (1) different human subpopulations (“races”) evolved in different physical and community ecologies; (2) these ecologies should at least partially determine the selective pressures shaping the evolution of human life history strategies in different parts of the world; ergo (3) different human subpopulations (“races”) should be associated with different modal life history strategies. Although the argument seems sound in its stark logical form, however, there are several limitations to the way that things were operationalized. For example, the traditional “Big Three Races” used (Caucasoid, Mongoloid, and Negroid) do not correspond very closely to the six or seven major population clusters identified by modern genetics for the human species. Furthermore, these “races” are neither completely discrete nor mutually exclusive, as they have many zones of overlap and interbreeding, which make setting geographical boundaries fuzzy and imprecise. Moreover, fixing the “race” issue will still not directly address what we take as the fundamental premise of the theory: That of human life history strategy being largely determined by ecological factors.
The present study addresses that last point directly by using the updated zoogeographical regions (Holt et al. 2013), based on data from over 21K species of terrestrial vertebrate, to establish ecologically-informed geographical areas within which humans (and other species) can be expected to evolve and develop different life history adaptations. By dividing modern humans roughly into such regional ecotypes, instead of conventionally-defined “races”, we can more directly test the basic premise of Rushton’s hypothesis, while avoiding much of the unnecessary controversies surrounding the definitions and utilities of such historically-received but antiquated racial concepts. We only used regions for this analysis which were still inhabited mostly by the aboriginal populations that existed there prior to the 15th Century AD. The results, although obtained by procedures quite different from those used originally by Rushton (1985) and subsequent works, nevertheless produced results that were surprisingly convergent with the basic premise underlying the original hypotheses.

The first industrial revolution. Did cold seasonal climates select for cognitive ability?
Peter Frost, Université Laval, independent researcher
Abstract: In their joint article, Rushton and Jensen argued that cognitive ability differs between human populations. But why are such differences expectable? Their answer: as modern humans spread out of Africa and into the northern latitudes of Eurasia, they entered colder and more seasonal climates that selected for the ability to plan ahead, since they had to store food, make clothes, and build shelters for the winter.
This explanation has a long history going back to Arthur Schopenhauer. More recently, it has been supported by findings from Paleolithic humans and contemporary hunter-gatherers. Tools become more diverse and complex as effective temperature decreases, apparently because food has to be obtained during limited periods of time and over large areas. There is also more storage of food and fuel and greater use of untended traps and snares. Finally, shelters have to be sturdier, and clothing more cold-resistant. The resulting cognitive demands fall on both men and women. Indeed, because women have few opportunities to get food through gathering, they specialize in more cognitively demanding tasks like garment making, needlework, weaving, leatherworking, pottery, and use of kilns. The northern tier of Paleolithic Eurasia thus produced the "first industrial revolution"—an explosion of creativity that pre-adapted its inhabitants for later developments, i.e., agriculture, more complex technology and social organization, and an increasingly future-oriented culture. Over time these humans would spread south, replacing earlier populations that could less easily exploit the possibilities of the new cultural environment.
As this cultural environment developed further, it selected for further increases in cognitive ability. In fact, mean intelligence seems to have risen during historic times at temperate latitudes in Europe and East Asia. There is thus no unified theory for the evolution of human intelligence. A key stage was adaptation to cold seasonal climates during the Paleolithic, but much happened later.

Psych EISSN 2624-8611 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top