Genetic and environmental contributions to cranial capacity in black and white adolescents

Rushton, J. Philippe; Osborne, R. T.

doi:10.1016/0160-2896(95)90002-0

Cited by 27 publications

(23 citation statements)

References 30 publications

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“…It found that after adjusting for the effects of body size and sex, samples from the Pacific Rim, Europe, and Africa had average cranial capacities, of 1,308, 1,297, and 1,241 cm 3 respectively. Finally, Rushton and Osborne (1995) analyzed the Georgia Twin Study of adolescents and found that after correcting for body size and sex, Whites had an average cranial capacity of 1,269 cm 3 , Blacks 1,251 cm 3 . Rushton's results, based on calculating average cranial capacity from external head size measures, join those from dozens of other studies from the 1840s to the present on different samples using three different methods (endocranial volume from empty skulls, wet brain weight at autopsy, and high-tech MRI).…”

Section: Race Differences In Cognitive Abilitymentioning

confidence: 99%

“…For example, Rushton and Osborne (1995) reanalyzed 125 Black and 111 White pairs of 12-to 18-year-old twins from the Georgia Twin Study and estimated their cranial capacities from head size measures. They found a lower range of heritabilities for Blacks than for Whites (12% to 31% against 47% to 56%) and a higher range of common environmental (i.e., shared family) effects for Blacks than for Whites (42% to 46% against 28% to 32%).…”

Section: Section 2: the Two Conflicting Research Programsmentioning

confidence: 99%

“…Several other studies supporting the brain-size/efficiency model were reviewed in Gignac, Vernon, and Wickett (2003). In any individual, however, energy use increases with the increasing complexity of the cognitive task.Estimates from twin studies indicate that genes contribute from 50% to 90% of the variance to both cranial capacities based on external head size measures and to brain volume measured by MRI (Bartley, Jones, & Weinberger, 1997;Pennington et al, 2000;Posthuma et al, 2002;Rushton & Osborne, 1995;Thompson et al, 2001). Common genetic effects mediate from 50% to 100% of the brainsize/IQ correlation (Pennington et al, 2000;Posthuma et al, 2002).…”

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Thirty years of research on race differences in cognitive ability.

Rushton¹,

Jensen²

2005

Psychology, Public Policy, and Law

375

405

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The culture-only (0% genetic-100% environmental) and the hereditarian (50% genetic-50% environmental) models of the causes of mean Black-White differences in cognitive ability are compared and contrasted across 10 categories of evidence: the worldwide distribution of test scores, g factor of mental ability, heritability, brain size and cognitive ability, transracial adoption, racial admixture, regression, related life-history traits, human origins research, and hypothesized environmental variables. The new evidence reviewed here points to some genetic component in Black-White differences in mean IQ. The implication for public policy is that the discrimination model (i.e., Black-White differences in socially valued outcomes will be equal barring discrimination) must be tempered by a distributional model (i.e., Black-White outcomes reflect underlying group characteristics). Section 1: BackgroundThroughout the history of psychology, no question has been so persistent or so resistant to resolution as that of the relative roles of nature and nurture in causing individual and group differences in cognitive ability (Degler, 1991;Loehlin, Lindzey, & Spuhler, 1975). The scientific debate goes back to the mid-19th century (e.g., Galton, 1869;Nott & Glidden, 1854). Starting with the widespread use of standardized mental tests in World War I, average ethnic and racial group differences were found. Especially vexing has been the cause(s) of the 15-point Black-White IQ difference in the United States.In 1969, the Harvard Educational Review published Arthur Jensen's lengthy article, "How Much Can We Boost IQ and School Achievement?" Jensen concluded that (a) IQ tests measure socially relevant general ability; (b) individual differences in IQ have a high heritability, at least for the White populations of the United States and Europe; (c) compensatory educational programs have proved generally ineffective in raising the IQs or school achievement of individuals or groups; (d) because social mobility is linked to ability, social class differences in IQ probably have an appreciable genetic component; and tentatively, but most controversially, (e) the mean Black-White group difference in IQ probably has some genetic component. Jensen's (1969) article was covered in Time, Newsweek, Life, U.S. News & World Report, and New York Times Magazine. His conclusions, the theoretical issues they raised, and the public policy recommendations that many saw as stemming directly from them were dubbed "Jensenism," a term which entered the J. Philippe Rushton, Department of Psychology, The University of Western Ontario, London, Ontario, Canada; Arthur R. Jensen, School of Education, University of California, Berkeley.Correspondence concerning this article should be addressed to J. Philippe Rushton, Department of Psychology, The University of Western Ontario, London, Ontario N6A 5C2, Canada. E-mail: rushton@uwo.ca Psychology, Public Policy, and Law 2005, Vol. 11, No. 2, 235-294 Copyright 2005 by the American Psychological Association 1076-8971/0...

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Section: Race Differences In Cognitive Abilitymentioning

confidence: 99%

Section: Section 2: the Two Conflicting Research Programsmentioning

confidence: 99%

mentioning

confidence: 99%

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Thirty years of research on race differences in cognitive ability.

Rushton¹,

Jensen²

2005

Psychology, Public Policy, and Law

375

405

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“…An earlier study had reported Caucasians to have higher mean TIV values than the Negroes [19]. A comparison of the mean TIV from our study and other studies in other populations showed mild to moderate variation in values which probably due to differences geographical location and race as reported in literature [3,4].…”

Section: Discussionmentioning

confidence: 55%

Assessment of the Total Intra-Cranial Volume of the Igbo Population of Nigeria Using Computed Tomography

Onwuzu¹

2017

RST

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Abstract:Total intra-cranial volume (TIV) of the Igbo population of Nigeria was carried out using stereology technique. A total of 329 adult subjects of Igbo ethnic group with no cranial and brain abnormalities aged between 18 and 87 years were enlisted into the study (males: 193 and females: 136). They were scanned with a helical dual detector (GE Hi-Speed NX/i Series 8.1). Images were obtained with a slice thickness of 3 mm from the base of the skull to the vertex. Employing the Cavalieri's sections method with point counting, a grid with a separation distance of 2.4cm was superimposed on the sampled image sections to calculate the TIV of each subject. The mean TIV of males and females were 1298.44 ± 90.67 cm 3 and 1186.73 ± 79.05 cm 3 respectively. A comparison of the mean TIV from our study and other studies in other populations showed mild to moderate variation in values which probably due to differences geographical location and race. There was significant difference (p< 0.05) in the value of TIV in the Igbo population when compared with some other populations such as Turkey using the same methodology. Total intra-cranial volume estimate can be applied in forensic investigations to differentiate various ethnic nationalities, in addition to clinical assessment in quantitative imaging to assess disease progression.

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“…Rushton calculated the skull and brain size and displayed that height, weight and body surface have effects on skull size. He also stated that difference in races results in different in skull size and described the skull size differences between different races on this basis (Rushton, 1991(Rushton, , 1992Rushton & Osborne, 1995).…”

Section: Discussionmentioning

confidence: 99%

Correlation of Skull Size and Brain Volume, with Age, Weight, Height and Body Mass Index of Arak Medical Sciences Students

et al. 2012

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SUMMARY:Anthropometric indices that are indicators of nutrition status in children and adults can be affected by racial and geographic factors. The aim of present study was to investigate the relation of skull size and brain volume of Arak University of Medical Sciences students with their age, weight, height and body mass index. The present study was a cross-sectional study on 18-26 years old students of Arak University of Medical Sciences (150 female and 136 male) in 2009-2010 educational year. Sampling methods were probability and multi-stage methods which were performed using students' educational file and interviewing the subjects. Questions regarding anthropometric data (height, weight, age, body mass index and skull index) were included in the personal questionnaires. Data was analyzed and evaluated statistically using SPSS statistical software. Mean height was 177.27±6.41 cm in males and was 166.61±5.35 cm in females. Mean weight of males was 73.33±9.11 kg and mean weight of females was 55.55±7.28. Mean BMI was 23.20±2.43 and 21.27±2.69 in males and females, respectively. Mean skull index was 1.99±0.26 in males and 2.20±0.3 in females. Mentioned data were significantly different between males and females. Also mean age of females was less than males. Positive relations were found between skull volume and height, weight, age and BMI in both sexes and this relation is stronger regarding BMI. The present study, supporting the other studies in this field, confirms the relation between skull index and body mass index and indicates the effect of race. Considering the studied population which are students of Arak University of Medical Sciences and are from different regions of the country, similarities between results of this study and studies from Iran and studies conducted in a special region reveals that factor of race is affected by geographical factors.

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Genetic and environmental contributions to cranial capacity in black and white adolescents

Cited by 27 publications

References 30 publications

Thirty years of research on race differences in cognitive ability.

Thirty years of research on race differences in cognitive ability.

Assessment of the Total Intra-Cranial Volume of the Igbo Population of Nigeria Using Computed Tomography

Correlation of Skull Size and Brain Volume, with Age, Weight, Height and Body Mass Index of Arak Medical Sciences Students

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