Thousands of years before the word “testosterone” existed, before anyone had heard of hormones, before endocrinology was a field or even a concept — humanity was running a very large, very involuntary clinical trial on the effects of removing testosterone from men.
We know it as the history of eunuchs. In the language of modern medicine, we would call it the world’s longest longitudinal study of male hypogonadism.
The data is in. The methodology was terrible. But the results were unmistakable.
The Scale of This
The castration of men was not an unusual practice in antiquity. It was an institution.
The earliest documented creation of eunuchs in China dates to approximately 1300 BC — more than three thousand years ago. The Chinese eunuch system persisted, with thousands of eunuchs existing at any given time, until the end of the imperial period in 1912. The last Chinese eunuch, a man named Sun Yaoting, died in 1996 at the age of ninety-four.
Think about that. The Chinese imperial eunuch system lasted longer than the Roman Empire. Longer than medieval feudalism. It overlapped with the Industrial Revolution, with both World Wars, with the invention of the automobile. Sun Yaoting, who was castrated as a boy, lived to see television.
The scale across human history is staggering. It has been estimated that between 1450 and 1870, approximately 11.5 million Africans were transported across the Atlantic to the Americas. During the same general period — from 650 to 1920 — the Islamic deportation of slaves from Africa totaled approximately 17 million. Several million of those enslaved people were castrated.
This was not medicine. It was not science. It was, for the most part, a tool of control, punishment, and economic organization. But it produced, as an unintended byproduct, detailed empirical knowledge about what testosterone does to a man’s body — and what happens when it’s gone.
What the Data Showed
Physicians who examined eunuchs noted consistent physical patterns. A German anatomist named Wagenseil, who in 1922 established an institute at the Chinese-German Tung-Chi University in Shanghai, examined a series of thirty-one Chinese eunuchs aged forty-five to fifty-seven years. His findings were systematic.
No beard growth. Sparse body hair. Twenty-one of the thirty-one had developed kyphosis — the characteristic hunching of the spine caused by significant bone density loss. Classic osteoporosis, before that term existed in clinical use, caused by a lifetime without the bone-protective effects of testosterone.
The ancient world understood the behavioral effects in practical terms, even without the biochemistry. The physiology was used deliberately: eunuchs were valued precisely because removing testosterone removed aggression, ambition, and the drive to create competing offspring. They were considered trustworthy administrators, loyal servants, and reliable guards — the idea being that a man without the hormonal motivation to accumulate power, seize territory, or father children could be trusted to manage someone else’s palace.
This was, in a brutal way, a real understanding of testosterone’s role in motivation, competition, and social behavior — expressed through human exploitation rather than laboratory research.
The Castrati: Science in an Octave
There is one corner of castration history that’s slightly less grim, though not entirely so: the castrati singers of the 17th and 18th centuries.
Testosterone, during puberty, does several things to the male voice. It drops the pitch by thickening and lengthening the vocal cords. It enlarges the larynx. A boy castrated before puberty doesn’t undergo this process. What results is a voice with the pitch and tonal qualities of a child’s soprano, but with the lung capacity and physical resonance of an adult male body.
The effect was extraordinary — rich, powerful, and unlike anything else in music. Audiences went wild for it. The most famous castrati became international celebrities. Carlo Farinelli (1705–1782) was described in contemporary accounts in terms that would fit a modern rock star. Domenico Annibaldi drew similarly passionate audiences.
The middle Italian towns of Norcia and Preci became infamous centers for the operations. Thirty family dynasties had, for centuries, monopolized the trade in secret — extraordinary considering that castration was technically illegal even in the Papal States that controlled the region. The Vatican found a convenient workaround: it didn’t forbid employing castrated singers, only the castration itself.
It’s estimated that several thousand boys were castrated in pursuit of vocal careers. Most of them developed only mediocre voices and were ridiculed by their contemporaries — the operation had been sold as a guarantee of success that could not actually be guaranteed. The boys who didn’t make it as singers had traded their endocrine system for a probability, and lost.
One faint audio record survives. Alessandro Moreschi (1858–1922), the last Vatican castrato, made a series of gramophone recordings in 1902. The recording quality is primitive — it sounds like someone singing through an antique pillow — but what comes through is genuinely unlike anything else. It’s available today. History preserved in distortion.
The Lifespan Finding
One interesting footnote from the castrati data: when researchers compared the life expectancy of castrated male singers to that of intact male singers born during the same period (1580–1858), they found no statistically significant difference. The castrated singers lived on average 65.5 years; the intact singers, 64.4 years.
This is a small and imperfect dataset, but it suggests something that modern gerontology continues to debate: the presence or absence of testosterone, on its own, may not be the primary driver of male lifespan. It’s a finding that cuts against the folklore that testosterone is somehow hard on the body. The eunuchs were not, on average, noticeably longer-lived because of their castration.
They were just quieter about it.
What This Means
What three thousand years of involuntary human endocrinology showed us, long before anyone could articulate the mechanism, is this: testosterone governs phenotype, behavior, bone, muscle, and motivation in a way that is comprehensive and systematic. Remove it, and you remove a specific cluster of characteristics that are deeply interconnected.
The ancient world knew this empirically. The knowledge was used for control, for art, for punishment, and for power. It took science another couple of millennia to understand why.
What’s Next
The organized search for the actual hormone doesn’t begin until the early twentieth century — and when it does, it involves one of the most theatrical and bizarre chapters in medical history: wealthy men lining up to have monkey testicle tissue surgically implanted in their bodies.
For rejuvenation. In Paris. And then, when things went sideways, in Algeria.
It’s a story that has everything.
