The testis, eunuchs, and testosterone: a historical review over the ages and around the world.

Introduction: Testosterone therapy for men with testosterone deficiency is widely used, yet remains controversial. The rich and fascinating history of the testicles, including human castration, provides a valuable perspective on this important topic.

Objectives: This study reviewed the history of testosterone from antiquity to the modern day.

Methods: Primary sources consisted of books and relevant articles, augmented by a MEDLINE search using the key words "testis," "testicles," "castration," "eunuchs," "testosterone," and "testicular function."

Results: An early scientific observation was that castration reduced sexual development and activity, originating with domestication of animals approximately 10 000 years ago. Human castration appears in ancient Egyptian mythology more than 4000 years ago, in Greek mythology from 8th century BCE, and in the Bible. The history of eunuchs in China spanned 2000 years, beginning with the Hsia dynasty (2205-1766 BCE). The concept that the testicles produced some factor responsible for male sexual development and behavior was thus known throughout the world since the beginning of recorded history. Testosterone was isolated and synthesized in 1935 and was soon available as a treatment. Multiple benefits of testosterone therapy were apparent by 1940. Recent large, controlled testosterone studies have conclusively demonstrated sexual and general health benefits, with a strong safety profile.

Conclusion: Testosterone has been a known substance for <1% of the historical timeline, yet knowledge that the testes were responsible for male sexual development and behavior has been known since the beginning of recorded history. Today, modern evidence has demonstrated the importance of normal levels of testosterone for general health as well as sexual function and desire. Yet, testosterone therapy remains controversial. We believe this historical review provides a helpful perspective on this age-old issue.