Sexual dimorphism in facial shapes and their discrimination in Japanese monkeys (Macaca fuscata).

Full Abstract

The authors examined the ability of Japanese monkeys (Macaca fuscata) to discriminate between sexes based on facial features. The shape and position of facial features (facial morphology) were measured to quantify the differences between sexes. The distance between the chin and nose was longer in males than females, and the outline of the face around the upper jaw and upper face differed between sexes. Using operant conditioning, 2 monkeys succeeded in discriminating sex based on facial pictures. Furthermore, they successfully generalized the discrimination to novel pictures of faces. Tests with morphed pictures of faces revealed that the monkeys used facial morphology to discriminate between males and females. Our results suggest that Japanese monkeys have sexual dimorphism in facial shape and they can use the morphological differences to discriminate conspecific sex. Copyright 2009 APA, all rights reserved.

Author information

Author/s: Koba, Reiko (R); Izumi, Akihiro (A); Nakamura, Katsuki (K);

Affiliation: Department of Animal Models for Human Disease, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Japan.

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't

Journal: Journal of comparative psychology (Washington, D.C. : 1983) (J Comp Psychol), published in United States. (Language: eng)

Reference: 2009-Aug; vol 123 (issue 3) : pp 326-33

Dates: Created 2009/08/18; Completed 2009/09/25;

PMID: 19685975, status: MEDLINE (last retrieval date: 9/25/2009, IMS Date: )

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