Testosterone/ What's Left Behind
Joseph Everett — Journalist, Biohacker, Writer & Researcher, Creator @ What I've Learned
Joseph Everett delves into the profound psychological and behavioral effects of testosterone, a hormone whose
"Good relationships make people happy and healthy. Understanding hormonal effects, culture, and personality can help us have better relationships and understand ourselves and others better."
Summary
- Testosterone levels have declined worldwide over 30 years, impacting energy, mood, confidence, and social behaviors. - Testosterone boosts strength, focus, confidence, mood, pain tolerance, and reduces social anxiety and empathy. - It drives motivation for social status, competition, and risk-taking, influencing behaviors from sports to entrepreneurship. - Testosterone fluctuates with social hierarchy and competition outcomes, reflecting one's perceived social status. - Lifestyle factors like sleep, strength training, sunlight, weight loss, and supplements (zinc, vitamin D) influence testosterone levels.
Article
The hidden force shaping modern society: how falling testosterone levels are reshaping behaviour and motivation
**Exclusive research reveals the widespread psychological and social impacts of a hormone most associate only with muscles and aggression**
At the Hololife Summit 2025 in Tokyo, content creator and scientific researcher Joseph Everett presented findings that challenge conventional understanding of testosterone's role in human behaviour. His research, compiled over years of investigation and personal experimentation, reveals how declining global testosterone levels may be fundamentally altering everything from social dynamics to mental health.
A global decline with far-reaching consequences
Everett, who runs the educational channel "What I've Learned," shared a striking statistic: compared to thirty years ago, men today have, on average, testosterone levels about one hundred points lower. This isn't merely a medical curiosity. The decline, observed consistently worldwide over the past three decades, appears to correlate with shifts in behaviour, motivation and social interaction that extend far beyond the gymnasium.
"The question is: does this matter?" Everett asked his Tokyo audience. "Is testosterone being a bit lower a bad thing? Are men less aggressive, causing less trouble, or could it be beneficial for society?"
His research suggests the answer is more complex and concerning than many might expect.
Beyond muscle: the psychological landscape of testosterone
Most discussions of testosterone focus on its physical effects: muscle growth, bone density, fat distribution. However, Everett's work explores territory less frequently examined—the hormone's profound influence on psychology and behaviour.
"Testosterone is said to give you more energy—but energy to do what?" he noted. "Many people can play video games or scroll through social media endlessly without needing extra energy. So, what kind of energy does testosterone provide, and what is it used for?"
Drawing on research by James McBride and extensive animal studies, Everett outlined testosterone's impacts on strength, energy, concentration, confidence, persistence and intensity of focus. The hormone reduces empathy and the ability to recognise emotions in others, whilst lowering the likelihood of crying. It increases pain tolerance, reduces social anxiety and promotes extroversion.
Perhaps most significantly, testosterone demonstrates a powerful antidepressant effect. Studies indicate that higher doses improve mood even in individuals with normal testosterone levels, boosting confidence whilst reducing anxiety.
Everett experienced this connection firsthand during a gruelling personal experiment. After completing a marathon on the fifth day of a fast without eating, his testosterone plummeted ninety percent—from 840 to 82. "I felt a huge drop in confidence and mood, with increased anxiety and irritability," he recalled. "Thankfully, this lasted only a couple of days."
Cultural rituals and the pain tolerance connection
The research takes an anthropological turn when examining pain tolerance. Anthropologist David Gilmour's work "Manhood in the Making" documents how many cultures worldwide feature rituals for boys transitioning to manhood, typically involving enduring pain. Among the Fulani people in Africa, boys undergo a flogging ritual, where performing well can increase social status and even result in more wives.
"Enduring such pain may be a 'testosterone check,'" Everett explained, "since testosterone not only increases pain tolerance, but also reduces social anxiety, helping in situations requiring bravery."
This connection between testosterone and pain tolerance extends to modern contexts. The hormone's anti-anxiety effect, particularly regarding social anxiety, combined with increased extroversion, creates a physiological foundation for risk-taking behaviour that has implications throughout society.
The dating landscape and social risk aversion
As global testosterone levels decline, studies reveal more young men avoiding approaching potential romantic partners in person, perceiving such direct contact as socially risky. Instead, they opt for dating apps and digital communication.
"Lower testosterone levels might explain why fewer young adults approach potential mates directly, reflecting a shift in social motivation and risk-taking," Everett observed.
This change may result from lower testosterone, but it also reflects broader cultural transformations in how people navigate social interaction and romantic connection.
Agency, resilience and mental health implications
Testosterone increases resilience to stress and enhances what researchers call "agency"—the feeling that one's actions have meaningful effects on the world. Higher agency correlates strongly with greater well-being and happiness. Conversely, low testosterone may contribute to higher rates of depression and anxiety, which appear about twice as prevalent among women, possibly due to testosterone's protective effects being present at lower levels.
"Jordan Peterson once said that sometimes people think they're depressed when they're actually just at the bottom of their social hierarchy," Everett noted. "Low testosterone and diminished confidence might simply reflect one's social position, and a misalignment between one's capabilities and social context."
Status motivation and competitive drive
One of testosterone's most significant functions involves motivation to gain status. This could manifest as excelling at sports, earning more money or achieving competitive success in any realm. The hormone increases drive to be perceived as accomplished or "cool" within one's social context.
Robert Sapolsky's research illustrates how this status motivation adapts to different environments. Monks given testosterone might compete at performing the most acts of kindness—demonstrating that testosterone's motivation for status can channel into diverse domains depending on social context.
Competition and winning boost testosterone, whilst higher testosterone increases willingness to compete, creating a momentum effect. However, losing can result in dramatic testosterone drops. Studies across various animal species found testosterone levels closely tracking individuals' positions in social hierarchies—the "top dog" has the highest levels, whilst those at the bottom have the lowest.
In humans, managers and chief executives often demonstrate higher testosterone, though the relationship proves less straightforward due to differing values and priorities.
The innovation question
Testosterone's association with risk-taking and impulsivity raises intriguing questions about innovation and entrepreneurship. The hormone makes people more likely to stick with their first impulse or speak their minds regardless of group opinion. It may prevent overthinking but can also lead to mistakes.
"If testosterone levels are declining, could that lead to less innovation?" Everett asked. "It's possible."
The hormone also reduces lying in men. Sometimes telling the truth carries risk, and higher testosterone correlates with greater willingness to take that risk.
Evolutionary context and modern applications
Testosterone's varied roles may stem from evolutionary pressures. Hunting, an historically important male activity, required risk-taking, physical energy and spatial cognition. Testosterone improves spatial abilities like tracking moving targets, which translates to modern activities like racing.
"Testosterone increases spatial cognition, improving abilities related to tracking moving targets, which may explain male dominance in activities like racing and better parking accuracy," Everett explained.
Practical interventions: lifestyle and environmental factors
Modern factors including endocrine disruptors, poor sleep, insufficient protein and processed food diets contribute to declining testosterone, possibly preventing people from realising their true potential.
Everett's research identified several lifestyle strategies for optimising testosterone levels. Sleep, strength training and sunlight exposure all demonstrate beneficial effects, whilst soda consumption and smoking prove detrimental. Losing weight, increasing daily steps and getting more sunlight can improve testosterone levels.
Supplement options include zinc and vitamin D as core choices, with ashwagandha, Tongkat Ali, selenium, DHEA, shilajit, fenugreek, D-aspartic acid and boron potentially worth considering, particularly if free testosterone levels are low.
The heat sensitivity factor
The testicles demonstrate remarkable sensitivity to heat. Temperature increases as small as 0.8 degrees Celsius can significantly affect sperm and testosterone production. Prolonged sitting, tight clothing and even driving can all heat the testicles. Cooling interventions, particularly for those with varicocele (a condition impairing heat dissipation), may help maintain optimal testosterone production.
"Heat exposure, particularly to the testicles, can negatively impact testosterone production by affecting sperm production and androgen activity," Everett noted.
The momentum effect in practice
Higher testosterone increases motivation to exercise, and exercise itself boosts testosterone. Even brief social interactions, such as speaking to women for fifteen minutes, can increase testosterone, which in turn makes such interactions more likely.
Everett's fasting experiments revealed that whilst a five-day fast didn't dramatically drop his testosterone, refeeding doubled it, likely because fasting creates conditions for greater anabolic activity when eating resumes.
Beyond testosterone: the complex hormonal picture
Testosterone represents only part of the hormonal landscape. Free testosterone, androgen sensitivity, dihydrotestosterone, cortisol, prolactin and estrogen all play significant roles in the overall picture of hormonal influence on behaviour and physiology.
Understanding across genders
Whilst testosterone discussions often focus on men, its behavioural effects offer insights valuable to everyone. Carol Hooven of Harvard notes that understanding testosterone helps women understand men and themselves better. Recognising how hormones influence behaviour can improve relationships and communication.
Robert Waldinger's presentation about a seventy-year Harvard study found that the clearest predictor of happiness and health was good relationships. Whilst culture and personality often override hormonal influences, considering biological factors can help people understand and improve their relationships with others.
"Understanding testosterone's behavioral effects can improve interpersonal relationships by providing insight into gender differences in mood, motivation, and social behavior," Everett emphasised.
Looking forward
Everett announced that his comprehensive research will be published in book form in June, providing detailed exploration of testosterone's multifaceted role in human behaviour and society. His work, available through his Substack and YouTube channel "What I've Learned," continues to bridge the gap between technical research and public understanding.
The implications of his findings extend far beyond individual health optimisation. If declining testosterone levels are indeed reshaping motivation, risk-taking, innovation and social interaction on a societal scale, understanding this hidden force becomes crucial for addressing challenges in mental health, relationships, entrepreneurship and cultural dynamics.
As global testosterone levels continue their decades-long decline, Everett's research suggests we may be witnessing not merely a medical trend, but a fundamental shift in the biological foundations of human behaviour and social organisation. Whether this represents a crisis or merely an adaptation remains an open question—one that merits serious attention from researchers, policymakers and individuals alike.
Part of Hololife Summit 2025 Tokyo