The Case of the Sexually Arrested Orangutans

By Susan B. Chaplin, Laura J. Baumgartner

Abstract

This case examines the hormonal control of the development and maturation to adulthood and the role of stress hormones in that developmental process. The case was adapted from results summarized in Maggioncalda and Sapolsky’s (2002) article in Scientific American. It presents evidence for why an unusual adaptation for reproduction in subordinate male primates may have evolved as a means of reducing stress. Students are presented with data from the published studies and asked to analyze and interpret the results to formulate hypotheses. Initially developed for an upper division endocrinology course, the case has been used in an upper division comparative anatomy-physiology course, and could be used in an animal behavior or behavioral ecology course.

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Date Posted

01/13/2009

Overview

Objectives

Understand the normal homeostatic regulation of peripheral endocrine glands, such as the adrenal and gonadal glands by the hypothalamus and pituitary.
Describe how one life process such as growth and maturation is regulated by a variety of synergizing hypothalamic and pituitary hormones.
Describe the action of stress hormones on normal physiology.
Understand the “fight or flight” response.
Appreciate the effect of stress hormones on growth and development.
Understand the effect of hormones on behavior.
Evaluate data to determine whether it supports hypotheses.
Generate new hypotheses based on results presented.

Keywords

Orangutan; ape; primate; secondary sexual development; endocrine hormones; stress hormones; cortisol; alternative reproductive strategies; evolution; arrested development

Subject Headings

Evolutionary Biology

Physiology

Zoology

EDUCATIONAL LEVEL

Undergraduate upper division

FORMAT

PDF

TOPICAL AREAS

Scientific method

LANGUAGE

English

TYPE/METHODS

Interrupted, Journal Article