Author(s) :

Sonoma Peterson.

Volume/Issue :

Abstract :

Homo naledi (H. naledi) and Homo floresiensis (H. floresiensis) are hominin species that both display reduced sexual dimorphism. The factors that cause this reduction are debated. For H. naledi, two factors are debated as the primary causes. Those factors include the emergence of new tools, which make hunting easier, and pair bonding, which reduces male competition, leading to postponed adolescence and smaller canines and body size in males. Their mix of ancient and derived anatomical traits also makes it difficult for researchers to differentiate between the sexes. As for H. floresiensis, the island rule suggests that fewer resources result in a smaller overall body size for the species. The smaller overall body size increases pair bonding to fend off predators, which means less male competition, making things like larger canines and bigger body size a waste of energy. This review finds that while there is evidence supporting the theories of pair bonding, insular evolution, and reduced male competition, the current framework used for sex determination requires additional evidence to draw a definitive conclusion, and the available data remain too limited to distinguish whether these reductions reflect adaptive social strategies or developmental constraints.