Sun and Shade Trees: Rethinking Introversion and Extraversion

This paper introduces an ecological and evolutionary metaphor to reinterpret the psychological traits of introversion and extraversion. Drawing from forest ecology—specifically the distinction between sun trees and shade trees—it reframes personality traits as adaptive strategies embedded in institutional and cultural environments. The study critiques the limitations of frequency-dependent selection in explaining the high prevalence of introversion and proposes that introverted traits fulfill indispensable structural roles in complex societies. This framework contributes to structural psychological semantics by linking personality variation to ecological succession, cultural evolution, and institutional niche construction.