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Fluctuating asymmetry and psychometric intelligence
F B Furlow1, T Armijo-Prewitt, S W Gangestad
1Department of Biology, University of New Mexico, Albuquerque 87131-1091, USA. mycol1@unm.edu
Proceedings. Biological Sciences
|June 22, 1997
Summary
Human intelligence (IQ) differences may stem from genetic vulnerabilities to developmental stress. Body asymmetry, a marker of developmental instability, correlated with lower IQ scores in two student samples, suggesting indirect genetic influences on intelligence.
Area of Science:
- Developmental Biology
- Behavioral Genetics
- Human Intelligence Research
Background:
- The genetic basis of human psychometric intelligence (IQ) remains largely unknown.
- Heritability of IQ is often attributed to direct genetic influences on intelligence itself.
- An indirect genetic mechanism involving developmental stress is hypothesized.
Purpose of the Study:
- To investigate the hypothesis that IQ differences are partly due to heritable vulnerabilities to environmental developmental stress.
- To explore the relationship between developmental instability, measured by fluctuating asymmetry (FA), and IQ.
- To examine potential physiological mechanisms linking FA and IQ.
Main Methods:
- Fluctuating asymmetry (FA) of the body was measured as an indicator of developmental instability.
- Cattell's Culture Fair Intelligence Test (CFIT) was administered to assess psychometric intelligence.
- Two independent samples of undergraduates (N=112 and N=128) were studied.
Main Results:
- A significant negative correlation was found between FA and CFIT scores in both samples.
- Higher body asymmetry was associated with lower IQ scores.
- This suggests developmental instability is linked to reduced cognitive ability.
Conclusions:
- Findings support the hypothesis of an indirect genetic mechanism for IQ heritability via developmental stress.
- Proposed physiological explanations include compromised brain development or altered energy allocation in high-FA individuals.
- Improving developmental quality may enhance average IQ in future generations.
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