On folivory, competition, and intelligence: generalisms, overgeneralizations, and models of primate evolution

Area of Science:

• Primate behavioral evolution
• Evolutionary ecology
• Primate socioecology

Background:

• The "fruit/leaf dichotomy" is a criticized but persistent model in primate socioecology and brain evolution.
• This dichotomy limits understanding of the social and ecological complexities of primate folivory.
• Gray langurs (Semnopithecus entellus) exhibit significant ecological and behavioral plasticity despite folivorous adaptations.

Purpose of the Study:

• To examine the behavior of primate folivore-frugivores, focusing on gray langurs.
• To challenge traditional assumptions about primate folivory and socioecology.
• To explore the implications of gray langur behavior for evolutionary models.

Main Methods:

• Analysis of gray langur behavior and ecology within the framework of evolutionary ecology.
• Examination of dietary breadth and foraging strategies in relation to Liem's Paradox.
• Comparative analysis with other leaf-eating primates and frugivorous primates.

Main Results:

• Gray langurs display remarkable dietary breadth and inhabit diverse environments, including high altitudes.
• Contrary to classical views, gray langurs engage in resource competition and solve complex ecological problems.
• Their adaptability challenges the notion of constrained activity patterns associated with folivory.

Conclusions:

• Broad characterizations and subjective definitions are inadequate for understanding primate folivore adaptation.
• Primate adaptation, particularly in temperate zones, requires more nuanced approaches than simple categorization.
• A comprehensive understanding of primate ecology necessitates integrating proximate and ultimate mechanisms within mainstream evolutionary ecology.