The definition of the face.

Area of Science:

• Primatology
• Anatomy
• Ethology

Background:

• A universally accepted definition of the 'face' in humans and other primates is lacking.
• Primatologists often adopt the definition that the face encompasses all head structures visible from a frontal view.

Purpose of the Study:

• To explore the definition and characteristics of the primate face.
• To understand the functional unity of the face despite its anatomical heterogeneity.

Main Methods:

• Review of existing definitions and anatomical descriptions of the primate face.
• Analysis of facial structure and its relation to visual perception and social signaling.

Main Results:

• The primate face is a composite of diverse anatomical and functional elements (e.g., forehead, eyes, mouth, pelage).
• Despite heterogeneity, the face functions as a cohesive unit, particularly in facial expressions.
• Frontally oriented eyes and stereoscopic vision contribute to the importance of the face in primate visual displays and face-to-face interactions.

Conclusions:

• The definition of the face is primarily based on topographical anatomy, encompassing all structures visible from the front.
• The functional integration of diverse facial elements highlights the significance of the face in primate communication and social behavior.