Why g is not an adaptation: a comment on Kanazawa (2004)

Area of Science:

• Evolutionary psychology
• Cognitive science
• Psychometrics

Background:

• S. Kanazawa's theory posits general intelligence (g) as a species-typical information-processing mechanism.
• This contrasts with the conventional view of g as a source of individual differences, evidenced by the positive manifold.

Discussion:

• Kanazawa's conceptualization of g is critiqued as hypothetical and empirically unsupported.
• The authors argue that evolutionary accounts of g must address its role in individual differences.

Key Insights:

• Reconciling evolutionary theory with empirical data on general intelligence (g) is crucial.
• An evolutionary framework for g should explain individual variation, not just species-typical processing.

Outlook:

• Future research should focus on evolutionary models of g that incorporate individual differences.
• This approach will strengthen the empirical grounding of general intelligence theories.