Testosterone: An Unauthorized Biography

by Rebecca M. Jordan-Young, Katrina Karkazis (Contributor), Emily Durante (Narrator)

Testosterone is not what you think it is, and it is decidedly not a "male sex hormone." Here is the authoritative life story of a maligned and misunderstood molecule.

Testosterone is a familiar villain and attractive bad boy that supplies a ready explanation for innumerable social phenomena, from the stock market crash and the overrepresentation of men in prisons to men's dominance in business and politics. It's a lot to pin on a simple molecule.

Yet your testosterone level doesn't predict your competitive drive or tendency for violence, your appetite for risk or sex, or your strength or athletic prowess. It's neither the biological essence of manliness nor even "the male sex hormone." This unauthorized biography pries T, as it's known, loose from over a century of misconceptions that undermine science even as they make social fables about this hormone seem scientific.

T's story didn't spring from nature: it is a tale that began long before the hormone was even isolated, when nineteenth-century scientists went looking for the chemical essence of masculinity. And so this molecule's outmoded, authorized biography lived on, providing ready justification for countless behaviors--from the boorish and the belligerent to the exemplary and enviable. What we think we know about T has stood in the way of an accurate understanding of its surprising and diverse effects. Rebecca Jordan-Young and Katrina Karkazis focus on what T does in six domains: reproduction, aggression, risk-taking, power, sports, and parenting. At once arresting and deeply informed, Testosterone allows us to see the real T for the first time.

Genres: Nonfiction, Science, Gender, Feminism, Queer, Biology, History

Audible Audio

First published October 15, 2019

About the author

Rebecca M. Jordan-Young, is an American feminist scientist and gender studies scholar. Her research focuses on social medical science, sex, gender, sexuality, and epidemiology. She is an Associate Professor of Women’s, Gender, and Sexuality Studies at Barnard College.

Reviews

[Alok Vaid-Menon · Rating 5 out of 5]

Humans are extraordinarily complex and diverse. We should be skeptical of simple narratives promoting “biological truth” about “human nature.” When it comes to conversations about biological sex people often rely on gender stereotypes, not empirical data. In their research, Dr. Karkazis and Dr. Jordan-Young conduct a comprehensive survey of the medical literature on hormones to dispel myths about testosterone. They argue that contrary to popular belief: there is no conclusive evidence that testosterone level predicts aggression, sexual desire, strength, and athleticism.

Testosterone is not a “male sex hormone,” it is a steroid hormone found in all genders and sexes and has multiple functions (including in ovulation). This multiplicity of testosterone has been ignored because of the folk tale of testosterone as the biological essence of manhood. The gendering of testosterone is a “zombie fact,” (54) an idea that won’t be put to rest despite overwhelming evidence otherwise. This is because people are more committed to reinforcing pre-determined narratives instead of actually addressing reality.

Researchers willfully ignored findings which found that testosterone was involved in traditionally “feminizing” processes and that estrogen was involved in “masculinizing” processes. They instead devised the sex hormone concept of a dichotomy between testosterone and estrogen, framing them as a heteronormative pair that is “binary, dichotomous, and exclusive, each belonging to one sex or the other” (10). These categories are actually “conventional, not natural” (41) and prevent us from understanding what testosterone actually is and does.

Testosterone is a multipurpose hormone with a host of uses in almost every body. Yes, testosterone is found in organs of sex development, but it is also found almost everywhere else: blood, saliva, urine, brain, muscles, skin, internal organs. Testosterone should not be reduced to a singular hormone, it is a multiplicity that has different expressions in different contexts. In response to the claim that “testosterone increases aggression,” we should ask: “Which testosterone increases which aggression in what context?” (15) Specificity is so often sacrificed in the pursuit of stereotypes.

Dr. Karkazis and Dr. Jordan-Young conclude that “it’s far too simplistic to say that testosterone is the single most important determinant of athleticism” (159). In fact, studies of testosterone levels among athletes “fail to show consistent relationships between T and performance…[and] quite a few studies even find a negative correlation” (161). Considering that “sports require different kinds of strengths,” we should question “how do we define strength?” (161). Strength is not generic (164).

Evidence that T builds muscle, makes you strong, and makes you more competitive are “elusive, partial, and contextual,” (176) instead there is more evidence that athletic training and competition affect T than the other way around. Sports officials are much more likely to accuse Black and brown women from the Global South (like Caster Semenya) of having unfair advantages for their naturally occurring testosterone levels. This is part of an ongoing strategy of attempting to legitimize racism using the guise of science. Black and brown women are competent and talented and this system will do everything it can to undermine their achievements.

People often take their pre-existent ideas of what the world *should* be like and pepper them with “sciency details that. make them seem more alive, plausible, and engaging” (132). That doesn’t make their beliefs actual science. Science requires replicable data to make claims about human behavior. Always fact check, ask for sources, and investigate research design and methods.

[Yomna Abdelazim · Rating 3 out of 5]

بشكل شخصي أحب كتب تبسيط العلوم وتحمست للكتاب وموضوعه الجديد. الكتاب يقوم على تقديم الأبحاث والنظريات المشهورة في مجال البحث العلمي عن الدور الذي يلعبه هرمون التستوستيرون (ت) وتأثيره على سلوكيات الرجال من العنف والجريمة والمغامرة وتفوق الرجال في مجالات الرياضة. حيث تستعرض الباحثتان تلك الدراسات بالتفصيل الممل والرد عليها وتفنيدها من خلال إيجاد الثغرات في بناء تلك الأبحاث والمغالطات المنطقية وطرح بعض التساؤلات المهمة عن الشفافية في الافتراضات التي تقدمها تلك الأبحاث. فنرى كيف يمكن أن تقوم الأبحاث بتأصيل العنصرية العرقية ضد السود أو الأسيويين أو غير الغربيين لصالح الرجل الأبيض. وكذلك كيف يمكن القفز على النتائج والافتراضات للوصول لنتائج محددة للتحيز للرجال ضد النساء.

موضوع الكتاب شيق لكن طريقة العرض تخللها الكثير والكثير من الإعادة والتكرار والاستفاضة والاستطراق والاستطراد مما أصابني بالملل في أوقات كثيرة، فضلًا عن أن الترجمة لم تكن سلسة.
المشكلة الأخرى في رأي هي أن بعض الحجج والمعارضات المنطقية أو العلمية التي قدمتها الباحثتان في رأي لم تكن قوية بما يكفي للقول بأن الأبحاث محل الفحص غير دقيقة أو غير علمية. واستوقفني أيضًا أن الباحثتين في بعض الأوقات ساقت بعض النماذج الاستثنائية لتقديمها على أنها الأساس أو القاعدة.

الكتاب يحاول تقديم سردية جديدة لدور هرمون ت من الناحية الاجتماعية والثقافية في مقابل السردية العلمية المعروفة لهرمون (ت).
هل ت هو من يحدد سلوكيات مثل القوة والشجاعة والمجازفة أم هناك عوامل أخرى تتعلق بديناميكيات القوة وتداخل العوامل من الجندر والعمر والطبقة الاجتماعية والثقافة هي التي في النهاية ترسم الحدود التي يتصرف الإنسان من خلالها.
كانت الدراسات دائما تشير إلى ت أنه هو من يحدد تلك السلوكيات ولكن هذا الكتاب/الدراسة يشير إلى عوامل وجوانب اجتماعية لطالما تم إغفالها لصالح (ت).
"نريد تسليط الضوء على كيفية تفاعل الجنسانية والفقر والمراكز الاجتماعية المختلفة في هيكلة فرص حياة الشخص وخياراته والمجازفات والفوائد التي تعود على هذا الشخص من مختلف الأفعال".
تجادل الباحثتان بأن العلماء سابقًا افترضوا أن ارتفاع هرمون (ت) هو الذي يتسبب في ميول العنف والجريمة لدى الرجال.
بينما أظهرت بعض الأبحاث المتقدمة العكس وهو أن الميل للجريمة والعنف مع الوقت يتسبب في رفع هرمون ت لدى الذكور.
كذلك الأبحاث في السابق كانت تتحدث عن أن الرجال الذين يتمتعون بارتفاع هرمون ت هم من يفوزون بالمناصب المرموقة ويحققون مكانة اجتماعية جيدة.
بينما ترى الأبحاث المتقدمة أن العكس هو الصحيح وهو أن ارتفاع هرمون (ت) يدفع الكثيرين لسلوكيات تؤدي بهم في النهاية للفشل التعليمي والوظيفي. فالطفل الذي يتمتع بارتفاع هرمون ت لا يتحمل الانصياع للنظام المدرسي ولا يتقبل توجيهات المدرسين مما يدفعه خارج المنظومة التعليمية ومن ثم سيلتحق بالوظائف الأدنى والمكانة الاجتماعية الأدنى.

بداية معقولة لطرح النقاش في هذا الموضوع وسيحتاج للمزيد من الأبحاث العلمية التي تؤكد أو تنفي طرح هذا الكتاب.

23/02/2026

[عبدالرحمن عقاب · Rating 3 out of 5]

هذا كتاب عن "التستوستيرون" هرمون الذكورة، الذي يرتبط في ذهننا بالذكورة والفحولة، وبالرغبة الجنسية المشتعلة، والتنافس المحموم، والمغامرات المتطرفة، والعنف والقوة، وما يقابله من صفات الأنوثة وعلامات الخصوبة، وما يتحدّاه من الأبوّة المقيّدة.
لكنّ مؤلفتي الكتاب (ريبيكا وكاترينا) يطرحان لهذا الهرمون سيرة أخرى وصورة أخرى؛ حين يسائلان الأبحاث التي طرحت تلك الروابط والأفكار "الشهيرة"، ويعيدان قراءة النقود العلمية لها، والأبحاث الأخرى التي لم تحظَ بالشهرة لسببٍ أو آخر. فتبدوا تلك "الحقائق" المعروفة مجرد أوهامٍ وعناوين صحفية تُكرّر وتُتبنّى لمحض أسباب اجتماعية أو اقتصادية.
والكتاب مزدحم بالدراسات والنقود عليها، وكثير الاسهاب والتكرار. وهذا ما أزعجني به، وجعلني أستثقل أسلوبه.
ولكني أجد في الكتاب طرحاً عميقاً ومهماً لأمثلة –ترتكز على هرمون التستسوتيرون هنا- على ما يمكن أن نسميه "العلوم الرائجة" في المجال العلمي والأكاديمي التي تروّج لها الصحافة والثقافة العامة إلى أن تصير "بدهيات علمية" و"حقائق كونية"، وما تحمل تلك العلوم من "افتراضات" تبدو جامدة راسخة، وهي في حقيقتها سرابٌ يخلقه هوى الباحث حيناً وتحيزاته البحثية، أو تحمله وتُخيّله تربة خصبة من البيئة الثقافية أحياناً أخرى.

[FlyingBulgarian Svetli H. · Rating 3 out of 5]

I am with other reviewers who are slightly disappointed with the book. I agree that some of the chapters felt unfounded in science and their comparisons and arguments weak. But I was drawn to the book for one chapter only, which was about testosterone’s role in the female reproductive system - and frankly that chapter was extremely helpful, insightful and interesting. A few takeaways:
1. Testosterone is produced by the ovaries, adrenal glands but also from conversion from peripheral tissue
2. Insensitive testosterone receptors could be the reason some women have high testosterone without any other problems
3. Testosterone in saliva, blood and urine are not perfectly correlated
4. Testosterone is related to the distribution of fat in the body
5. Testosterone fluctuates throughout the day and is affected by multiple things - time of day, coffee, alcohol, sleep, mood, season, sunlight, temperature, social exclusion etc (so fickle!)
6. Testosterone results are not very accurate at the low ranges (I.e. for women)
7. Testosterone has an important role to play in follicular maturity for ovulation up to 12 months prior to ovulation

I found this extremely insightful and interesting. The rest of the chapters, not so much - but that’s again because I picked the book up ONLY for this chapter.

[Ali · Rating 5 out of 5]

"T is not, at root, evolution’s proximate mechanism for generating either masculinity or heteronormative coupling. It’s a transcendent, multipurpose hormone that has been adapted for a huge array of uses in virtually all bodies"

Sometimes when I start a review, I comment that the book was a different book than the one I wanted it to be. It's rare - ok unique - for a work to convince me that what I thought I wanted to know wasn't what I needed to know. Testosterone: An Unauthorized Biography has few clear answers on how T affects human behaviour, but it is a very detailed, powerful and scientific exploration of why we might need to embrace ambiguity in this space, which eventually won me over. The science here is meticulous, and better because it does not pretend that the scientific method is impenetrable or incontrovertible.
Some of my initial frustration stems from a dynamic in popular science around gender, where positive claims are often made regarding biological mechanisms of traditional gender difference, then feminist scholarship focuses on debunking claims, rather than positive arguments. It is, of course, easier to debunk bad science than to demonstrate new findings. At the same time, global finding trends create little incentive for science which disproves, compared with new discoveries, leading to a real shortage of critical analysis and study replication, so the work of those like Cordelia Fine is very important.
Testosterone, however, is easily the aspect of biological sex with the most evidence of impact on behaviour. While Fine recently wrote a book with Testosterone in the title, it barely focused on the hormone. When it did deal with T, it focused on debunking the association with risk-taking, fairly easy to do, given that no definition of "risk-taking behaviour" holds up for more than five minutes*. Risk-taking is easy to debunk, but the evidence around T's connection to aggression and competition is not as simple. In the non-human biological sciences, T is well-understood to be associated with these behaviours. So I was frustrated when at the outset, Jordan-Young and Karkazis explicitly excluded non-human biologies from consideration. There are well-worn arguments on both sides of this debate - on the one hand, Jordan-Young and Karkazis are right that the experience of the vast volume of rodent studies are of limited applicability to human biology and cultures, on the other, ethics prevent us from conducting the same kinds of studies on humans - or even other primates - that are carried out on rodents and birds, and T is associated with aggression in a large number of species, not just rodents.
Tightening the scope enables a relatively comprehensive analysis of studies, carried out I think with the assistance of many graduate students. This avoids cherry-picking to make a point, and means when, for example, the authors point out that none of the hundreds of studies, except Sari van Anders**' ones, cited any STS studies on gender and sexuality studies, this carries weight.
Jordan-Young and Karkazis do not, however, ignore the non-human body of research. They just haven't subjected it to the same kind of scrutiny that they have the studies within the scope of the book. And importantly, they do not deny that T impacts on human behaviour. Their argument boils down to "it's complicated" and no clear patterns have emerged in human behaviour. T comes in different forms (and is introduced in different ways) and intersects differently with different individual biologies. It carries such a multitude of varying effects that any attempt to generalise behaviour outcomes is problematic.
With non-human animals, the authors also point out that "Reciprocal effects between T and dominance are well documented. These complex and multidirectional effects of T are the “trouble with testosterone” that Robert Sapolsky has famously described. The long-standing assumption that animals with higher T rise to the top of dominance hierarchies gets it backward: evidence is much stronger that moving up the dominance hierarchy is what stimulates high T."
My interest in this topic stems from my interest in gender roles and how these debates influence gender equity conversations. T is increasingly at the centre of these debates, as I have acquaintances who can rail against any suggestion of biology-as-gender in child-rearing, and discuss the personality-altering effects of hormonal gender transition treatments on the other. Where I was more ignorant is in the impact of these discussions on race - specifically that the association of T and aggression has been largely used to justify racist incarceration outcomes: if high T causes criminality then that might be why African-American men are locked up in such high numbers. I would like to think that this hasn't previously occurred to me because it is so patently absurd - using criminal convictions as a proxy for aggression is every bit as absurd as using stock trading as a proxy for risk-taking: people make choices based on available options, and at least a cursory look at those options is essential to understanding their choices. Or as our authors put in, in surprisingly graceful academic language, "
in practice, the process of embodiment—that moment where the social is imbibed and transformed into the biological—is not under investigation. In its place is a thin, shallow conceptualization of the social, which figures in the research as an assumed and homogeneous background to subjects categorized by race or class: race isn’t connected to social institutions and history, but is a collection of habits." This is, apparently, pervasive "None of the T studies we’ve seen consider how the racial and class composition of their samples are related to social institutions and the operations of power, and how these, in turn, shape the lives of the people they study, whether they are looking at prisoners, military veterans, schoolchildren, or business school students. Instead, the studies follow folk notions and reiterate the social canalization of power."
Some of the most quotable evidence here comes from the studies - strong and replicated - which uncomfortably show that fatherhood is associated with substantially lower T in Western peoples, but not in non-Western. This points to a complex intersection between social structures, T and behaviour which is intriguing, but far from firm. In one of the Western studies, men who attempted unsuccessfully to calm a (robot) infant, had a rise in T, those whose robot infant was receptive, saw a drop. These kinds of results - changes in hormonal balances, but in unpredictable ways, which could change subtly based on minute shifts in environment or context or biology permeate the book.
They also deal head-on, in the longest section of the book, with the racial subtext around preventing female athletes with high naturally occurring T from participating in elite sport. This section has hints of anger coming through, as the authors carefully and individually tear apart the arguments that such T provides a qualitative advantage, and also delve into the combination of racialized sexism - or sexualised racism - that underlies the concept of "normal" bodies.
I was a bit surprised to see another's criticism of the science of the authors, given that it is such a meticulous examination of scientific studies - far more so than most pop science books (If we have reached the point where any critical examination of science is anti-science, then science has clearly lost.). However, Jordan-Young and Karkazis clearly anticipated this, and provide some of the most thoughtful meditations of science I've read: "Facts are produced through specific questions, techniques, tools, and interpretive frameworks, and values are embedded in all of these. This is very different from saying that science is “just made up” or “the same as opinion.” It means instead that while the material world does indeed exist, we can only know that world through our human engagements with it. The best we can do is use our senses, which allow us to perceive and select only some data points out of all the possible phenomena that exist; transform those data by filtering them through our measures; and apply our own cognitive, linguistic, and disciplinary frameworks to shape the results into an interpretation that is meaningful to us. "
Towards the end of the book, Jordan-Young and Karkazis discuss many of the things that I am most interested in - the growing discussion of T not as a conservative argument for the status-quo, but the biohackers who view it as a portal to a better humanity: the ongoing consensus that T is somehow under our control. The authors warn: "For some, it might seem obvious that T can’t be used as a precision tool to confer vigor, focus, libido, and a sense of power. But our travels with T suggest that the majority of people would find it plausible and intriguing that you might use T in these ways. These “new projects” of using T walk a fine line between disruption and recapitulation of sex hormone ideology." In the end, the clear message of this book, is that T is still unknowable to us, and that without a bit of self-knowledge, about our own biases and tendencies, we will simply project onto it what we already see. "Questions about biology and human nature are inextricable from moral and political debates about the value of human variations, the possibilities for equality, and the urgency and feasibility of social change."
There is passion here for exploration, but caution against arrogance. This book has clearly been a labour of love and purpose, and I concur with their hopes that they " have opened a space for new ways of thinking about T that might emerge alongside [the traditional fable], maybe taking up more room and gaining momentum as T’s complexities are further elaborated. Instead of the titanic strength of Atlas, we hope we’ve suggested that T has other and better superpowers: a shape-shifting, moving, social molecule that serves as a dense transfer point for the micro-operations of biology and social relations of power at multiple levels."


*Jordan-Young and Karkazis mercilessly deconstruct these studies, importantly connecting understanding of risk for relative gain and loss matrix - that those with few resources and options take different choices than those with many of both. E.g. "But multiple lines of evidence suggest that status is an important mediating variable that might explain some or even all of the apparent association between T and risk-taking. In other words, “given that testosterone is a social hormone with a reciprocal relationship with social status, and social status has been found to drive risk-taking behavior,” the positive relationship between T and risk-taking might be spurious."

**Would van Anders write a book, please? This is the third book which has cited her work in ways which I have tried to follow up on, but all her research output is written for endocrinologists. I mean, I'm sure she has time on her hands, yes?

[Muriel (The Purple Bookwyrm) · Rating 4 out of 5]

More accurate rating: 7.5/10.

This was interesting: Testosterone: An Unauthorized Biography isn't so much about the steroid testosterone, and what it does or doesn't do in the body (including the brain, which is what neuro-sexists and anti-sexists tend to focus on), but rather about the way human beings conduct research into testosterones and its effects, the way we ask questions about testosterone and its effects, and the way we interpret the results of said research - all of which can be subsumed under the umbrella-term "T Talk".

Note, you will learn some facts, here and there, about what testosterone does in the human body, whether male or female, but it really isn't the focus of the book. For my part, I found testosterone's unexplored role in the ovulatory cycle absolutely fascinating... And would have liked to learn more about this. 😅 I also learned that no clear or simple relation exists between testosterone and aggressive behaviour, even in men; and that whilst testosterone plays a role in the regulation of libido - in both men and women -, the amount of bioactive testosterone necessary to enact that regulation is actually quite low, and adding more testosterone in will not magically resuscitate flagging sexual desire, again in either women or men. I stress these last two points because even I, a very gender critical feminist who believes very few behavioural differences between men and women can be neatly explained by purely physiological differences used to think there was a solid correlation between higher levels of testosterone in males and a greater potential for aggression, and another one between high T and a slightly higher average libido, or rather slightly higher and less discriminating libido, in men - women being more choosy but by no means naturally more chaste as such. But it seems the available research doesn't even quite support those relatively "intuitive" claims!

Of course, the authors only looked at studies involving metabolic testosterone in adults, because that is what was relevant to their specific enquiry. But that means the potential influences of anabolic testosterone during foetal and pubertal development were laid by the wayside, and I felt it stood as an elephant in the room at times, especially when the authors talked about sport and the debates surrounding testosterone levels in competing athletes - female athletes specifically.

Speaking of which: the book is divided into 6 chapters - female reproduction, violence, power, risk-taking, parenting and athleticism. I felt the latter was the weakest: the authors used bad-faith arguments, compared apple to oranges and got bogged down in moral philosophy when I wanted the book to get back to the science. I understand the book is basically a giant humanities-informed analysis of gendered endocrinology, but it just got tedious at times. This chapter wasn't as tight as the previous ones, especially when the authors kept coming back to intersex individuals to discuss female athletic performance. I mean, wouldn't being intersex precisely add a confounding variable? What were they even comparing then? Also, injecting the woke "science can't even precisely define sex" when the whole book clearly references male and female biology felt wonky and virtue-signalling-y as fuck. 🙄 I also noticed the authors conveniently left out the debate currently going on involving transgendered athletes in women's competitions from their analysis... So, I don't know, that whole chapter just felt off to me.

This book is really about the way humans conduct science, the way knowledge is acquired, and the biases we bring to the table when we do research - especially research that implicates our bodies, our minds, and our (often unfair) social structures. In that respect it is a very good book, though perhaps not quite what I was looking for? Still, it is most definitely true that what we think we know about testosterone - or any other hormone or neurotransmitter really, the same kind of book should be done for the way mental illness is studied in conjunction with neurotransmitter levels for example - is informed by an androcratic, classist and often racist history and society. It influences the very questions we ask, and the field of possibilities when it comes to gathering new items of knowledge in the fields of neuroendocrinology, neuropsychology or reproductive science.

Especially since testosterone, like any other molecular messenger and regulator, is a multi-purpose molecule that doesn't act, or react, the same way at all times, in all contexts or in all tissues. Bio-chemistry is complex as fuck, and you have to factor in different molecular configurations, receptor-molecule interactions, synergy between different hormones and neurotransmitters, etc... There isn't one T, but multiple Ts. And the same goes with oestrogen, cortisol, oxytocin, serotonin, etc...

Also, I agree with the authors that we should ditch the nomenclature of "androgens" and "oestrogens", since estradiol, progesterone, and testosterone all exist and work in both male and female bodies. Both men and women need optimal levels of all the sex steroids, so they should just be called sex steroids, though in truth they also play roles in other systems; but I don't think it's inaccurate to keep calling them sex steroids since they have primary functions in the reproductive system.

In conclusion, a worthwhile if imperfect read, if you're in the mood for a (largely) feminist-aligned analysis of science, rather than a feminist-aligned scientific treatise per se.

PS: and the whole "bio-hacking" with testosterone (or other sex steroids I presume) is also shown to be bullshit according to most available research - it just doesn't do what most people think it does, or does it in ways that are much more complicated than initially assumed.

[Richard Thompson · Rating 3 out of 5]

There's a whole lot of debunking going on in this book. Testosterone isn't really the male sex hormone. It has some function with building strength and aggression, but not always. It's connection to athleticism is varied. It plays a critical role for women in ovulation. A lot of the classic studies that supposedly established what we think we all know about testosterone turn out to have been bad science whose methods were tainted by p-hacking racism and misogyny. I did learn a lot and was disabused of some of my mistaken notions about testosterone, but I is found the book to be ultimately very unsatisfying. Ms. Jordan-Young goes on at great length in telling us what testosterone is not, but spends precious little of the book in explaining what it is. Her main answer seems to be "It's complicated." Oh come on. Surely she could have done better than that.

My other gripe about this book is that the tone and writing style are deeply infused with political correctness and academic jargon words that add nothing to clarity and serve only to provide a coded message that the author is card carrying member of the academic left. I'm not so far from being a member of the academic left myself, and I share the position that we need to take steps in our society to reexamine beliefs and systems that are too often built on racism and disrespect for disadvantaged groups, but I'm able to express my views without constantly using words like "heteronormative" and "interrogate" and "binary." This book could have used an editor with a stong hand to simplify and neutralize the writing style. That would have made the message more powerful and effective.

[Tim · Rating 5 out of 5]

For anyone looking for a complete rundown of what testosterone is and does in the human body: this is not that book.

This is a book about what we say that testosterone does that is not actually supported by the research that makes those claims — such as the connections between testosterone and aggression, dominance, and sexuality that are so culturally prevalent that we never think to question them. Even the links between testosterone and athleticism are far more tenuous than the lay person would have any reason to suspect.

The authors do a masterful job of breaking down the many unacknowledged social biases in the research on testosterone. These biases spawn methodological biases that are compounded by the research that seeks to build upon the earlier work. This is by no means a problem that is isolated to the research on testosterone, and in fact any research that attempts to map out human behaviour through the lens of biological determinism should be viewed with great scepticism.

[Mansoor · Rating 1 out of 5]

WTH, I was promised "to see the real testosterone for the first time. (from the publisher's note)"

[L. · Rating 4 out of 5]

This book is extremely interesting in its methodological criticisms and reflections on the current scientific work on testosterone. The authors debunk pervasive zombie facts and highlight the complexity and difficulty of adequately researching testosterone.

[Daniel R. · Rating 4 out of 5]

The myth of testosterone far exceeds what science can say about it. Systematically exploring testosterone research and opinion across ovulation, violence, power, risk-taking, parenting, and athleticism the authors point out p-hacking, pastiche science, and poorly designed studies. All of which intertwine and build upon each other to promote an incorrect and at times detrimental view of what testosterone is and is not capable of and responsible for.

[Melanie · Rating 5 out of 5]

An important book for anyone of any gender to read and understand the cultural narrative we put on "biological" masculinity that puts harmful pressure on cisgender men, insists on unrealistic expectations for trans men, hurts the professional aspirations of cisgender and trans women, and creates fictional binaries in gender that ultimately hurt us all. Easy to read with just the right amount of technical science talk and it covers the issue from all angles making clear that this so-called "male hormone" is much more complex than that.

[Marina · Rating 5 out of 5]

Who knew I could stay up late reading about the biology, politics, and sociology of a hormone. Really enjoyed this overview of scientific methodology and how it collides with public opinion. I highlighted so many telling passages, but here are a few of my favorites for those who don't have time to read the whole book:

▪ When we say we don’t take the science literally, we mean that we’re aware that scientific findings aren’t served up on a platter by Mother Nature. Instead, they are constructed out of specific research questions, the tools scientists use, and an enormous array of methodological choices, including what to measure and how, which groups or situations to compare, what statistical methods to use, and on and on. Critical excavation of science is not the same as rejecting facts, or saying that all observations or all evidence is relative. As the sociologist of science Bruno Latour observed more than a decade ago, “The question [for critical science and technology studies scholars] was never to get away from facts but closer to them, not fighting empiricism but, on the contrary, renewing empiricism.”

▪ ... agnotology, or the study of ignorance and how it is created, sustained, and used, is as important as epistemology, the study of knowledge. Asking “What don’t we know, and why don’t we know it? What keeps ignorance alive, or allows it to be used as a political instrument?,” scholars have examined ignorance in domains that include global climate change, military secrecy, female orgasm, environmental justice, archaeology and land claims, racial ignorance, and more.

▪ There are seasonal variations, too, but there is no universal pattern of circadian and seasonal variations with T. And some variation is just idiosyncratic. Dr. William Crowley of the Reproductive Endocrine Unit at Massachusetts General Hospital has observed “a funny disconnect between one measurement and a later one” in a number of men he has studied: they have very low T levels at one point but later have a “perfectly normal testosterone profile.” What’s more, the daily fluctuations in T that have been found in US and European populations aren’t found everywhere across the globe. And while many different studies around the world have found seasonal variations, the peaks and troughs don’t come at consistent times, and it isn’t clear what’s driving them. Sunlight? Temperature? Work patterns? Variations have been observed in people whose activities have seasonal patterns, like athletes during the off-season, the training season, and the competitive season. Others, such as farmers in rural Bolivia, who have huge variations in activity across the seasons, didn’t show any seasonal variation in T over the course of a year. These variations across populations, within populations, and within individuals are significant but not well understood. For most research questions, it doesn’t make sense to just take one T measure and think that you have captured an individual’s T as if it were a stable trait. But when taking multiple measures, it’s important to try to minimize sources of variation in T that aren’t relevant to the research question. Thus, most researchers measure T at the same time of day for all subjects, and for women they also factor in hormonal contraception and the menstrual cycle.

▪ If 15 percent of men with excellent health have T below the normal range, what’s the criterion for calling that range “normal”? This matters in medicine, but also in sports: how the “normal” ranges of T are calculated for men and women is central to a debate about regulating women athletes...

▪ Multiplicity is not, in the end, the main narrative that we pick up, but it is a crucial background fact. To be clear, the specificities and multiplicity of T do not mean there is no hope for a scientist who wants to pin T down. Scientists aren’t oblivious to this by any means—researchers working with T are the ones who have elaborated the importance of the different versions, after all. But the specificities have a way of slipping out of view at crucial moments in studies, and especially in review articles and other synthetic statements about what “T” (singular) does. The stubborn insistence on the specific version of T that does things in the body, that relates to other aspects of bodies and reciprocally engages with behaviors, means that synthetic statements are more elusive. That may frustrate researchers who are taught that good science is characterized by simplicity. But the apparent simplicity of this molecule is an illusion.

▪ It is helpful also to take an agnotology perspective—that is, to think not only about what has been persistently unknown or forgotten about female reproduction, but also about why these elements are forgotten, and how precisely that forgetting happens

▪ As with the studies of aggression and T that suggest patterns of violence and criminality can be explained by too much T, the power posing narrative uses T talk to shrink a huge social problem to the microenvironment of an individual body. If power posing can, as Cuddy says, “significantly change the way your life unfolds,” why bother directly confronting structural inequality? Standing with your hands on your hips provides a fast, individualized solution that is much more manageable than challenging entrenched systems. It’s the kind of argument that appeals to a liberal feminist sensibility, even as it obscures the radically different relationships to power among the homogenized category of “women.” In spite of the feminist sheen, the power posing approach actually counters a mainstay of feminist analysis and activism: gender inequality stems from social formations, not from biology. For those researching power posing, power is internal: postures shift state of mind and hormones, which in turn shift behaviors, creating power itself.

▪ In keeping with this cultural habit of imagining risk as risking money, most researchers studying risk-taking treat financial behavior as the epitome of risk-taking in humans. Of course, this skips over obvious problems, such as that you have to have money to risk money, and that who has money is determined by all kinds of external factors, like gender systems, social class, and global economic relations, as well as idiosyncratic life events.

▪ After three strikes with their planned comparisons, they turned to other measures that might show a link between cortisol and losses. This part of the paper reads a bit like a detective story, as the researchers detail their meticulous search for correlations, signaling the exploratory nature of their process with phrases like “we therefore looked” and “we suspected that” and “consequently, we looked to see whether …” You can almost hear the ship creaking as they turn their analysis to meet their data. This is the very definition of p-hacking.

▪ Jens Zinn, a sociologist who studies the phenomenology of risk, argues that “it does not make sense to speak about risk-taking when the decision-maker is not affected by the outcomes (which instead affect others). This could be called risk-making (for others) rather than risk-taking and follows a different logic.” The traders weren’t monetarily unaffected, but the bulk of the money at stake was not theirs. In other areas of life, people whose risk-taking ripples outward to create negative consequences for others, or whose risks break social and legal rules, are sometimes labeled as “antisocial,” “externalizers,” or even sociopaths. These terms are used in some of the studies on T and risk-taking, but tellingly, the studies of risk-taking among traders, CEOs, entrepreneurs, and business students don’t frame negative or irresponsible behaviors this way, even decidedly illegal activities like insider trading, options backdating and tax evasion, or cheating in business negotiations.

▪ The dangerous things that some groups of people do as a matter of course because of role expectations and material constraints are not typically examined as risks. For example, the epidemiologists Karen Messing and Jeanne Mager Stellman have documented the surprisingly extensive toxic exposures and high accident rates involved in domestic labor, a pattern obscured by the widespread notion of home as a “safe place.”32
So it’s not just desperation that makes people do dangerous things, it’s expectations, norms, and the daily circumstances of inequality. Consider the mundane behavior of asking for directions. This isn’t inherently risky, but the context can make it so, depending upon who you are, where you are, and whom you ask. In recent years, there have been innumerable accounts of black people going about their normal daily routines—asking directions, waiting in a cafe for business associates, playing in a park, driving, resting in a student lounge, and barbecuing are a few examples—who have faced extreme consequences ranging from arrest to assault to murder, at the hands of both civilians and the police, so many of whom have been white. Likewise, as Fine has pointed out, childbirth for a woman in the United States is about twenty times more likely to be fatal than skydiving. Even this surprising level of risk masks huge disparities by race and class. Black women continue to experience devastatingly high maternal mortality rates: more than four black women die for every thousand live births, while just over one white woman does. Native American and Alaskan Native women die at twice the rate of white women.33

▪ Science is not only storytelling, and this is why we insist on following the constructs and thinking about which specific version of risk or T is being mobilized in particular studies. But one story—the idea that T, via sexual selection, has ensured the pairing of maleness with a whole suite of traits and behaviors—is the glue that holds a whole body of research together. Narratives and data can also be fit into the rubric of “floaters” and “sinkers”: floaters are the stories and bits of data that get picked up from researchers’ discussions, abstracts, and titles and get cited in subsequent research, and the sinkers are the bits that don’t fit, the awkward gaps between hypothesis and data, the multiple analyses that are done offstage and never again mentioned. The data on risk-taking and T are weak at best, and certainly chaotic. But the narrative has a pleasing parsimony: T increases risk-taking.

▪ As we’ve seen, researchers make radically different uses of theories and data on T to explore patterns of parenthood in humans. At one extreme, purported racial variations in T and reproductive strategies are taken up to legitimize white supremacy and argue that human races literally have traveled different evolutionary trajectories. At the other extreme, shifts in T associated with the nurturing components of parenting are used to break the age-old designation of T as “masculine.” But it is important to be alert to the background narratives about good and bad parenting that are potentially activated by this work, especially when it is framed in terms of investments in offspring—even when these normative judgments run counter to researchers’ explicit commitment to a non-normative approach to human behavioral variations.

▪ It’s worth repeating that most of the researchers who use data on T to understand evolution and human parenting in no way endorse the uptake of that material for racist arguments. But resonance doesn’t require their active engagement. Synthetic theories about the evolution of human behavior, and about T as a mechanism in those processes, are like the warp and weft of a scientific and cultural fabric. Researchers don’t weave the fabric alone—no one could, as the field of data required is too vast. Instead, they must rely on other researchers’ work to supply some of the threads that get woven into the overall piece. Those threads, as well as the structure and language of the theory, build racial content into challenge hypothesis work in humans.

▪ Writing about this work presented us with similar challenges. Whether a citation is laudatory or outright condemnation, it underscores the importance of a piece of writing by showing that others have taken it seriously enough to engage with it. Links across studies lend each other mutual support, reinforcing the “fact value” of each through citation. We have opted to write about a number of egregiously racist studies in this chapter, especially, and wish that we could do so without citing them. As scholars, we need better strategies for responsibly identifying deeply problematic work without adding to its fact value.

[Andy Adkins · Rating 2 out of 5]

The author has cherry picked results from niche endocrine studies to establish a counter-intuitive narrative for testosterone's role in sexual biology, gender psychology, & athleticism. Early chapters in the book were, for this reason, quite engaging. The author, however, fails to adequately support her gender & athleticism premised conclusion by meticulously including details on study methods, participation statistics, & thoroughgoing discussions of testosterone's variously relevant conversion pathways.

[Laura · Rating 5 out of 5]

I was skeptical of a gender studies expert's ability to tackle the biochemistry and epidemiology study of hormones, but boy was I wrong. And boy is Testosterone so much more complex than a 'boy becomes strong aggressive man' narrative.
Rebecca Jordan-Young and co-author Katrina Karkazis slowly visit all the ingrained myths about testosterone and slowly take them apart with the thoroughness that would make any biochemistry expert proud. Among the problems highlighted in the book, some stood out for me:

- Testosterone (T as they refer to it) is often described as a 'male hormone' despite the fact that T is a) present in females as well and b) it can be metabolized into so called 'female' hormones as well. But there is more testosterone in males so surely it means it's more important for males, right? Well, it turns out that T is essential for one very female function: OVULATION. Shouldn't it inhibit ovulation, you may ask, and lead to polycystic ovarian syndrome. Well, it depends, it's all about balance. T seems to be essential for the early maturation of eggs, in the months prior to the final sprint from ovulation to potential fertilization. It turns out that many women unable to ovulate using 'female hormones' actually benefit from T or T precursor treatments, to the point where now it is part of the standard treatment for some women. But it's more complex than that.

- Low T means little effects and high T levels mean large effects, correct? Actually not. The T-response curve is not linear, meaning low T can sometimes have large effects. Sometimes T levels increase because the T receptor responds poorly to T levels (think of it as someone whose hearing is failing. You need to speak louder for them to understand what you're saying. Similarly, for some people the body produces more T because at regular levels the receptor is simply not doing its job properly so it needs a booster). Also, increasing T levels sometimes causes a negative feedback loop in the body.

- But athletes dope with T so obviously increasing T levels in the body leads to more muscle and better athletic performance, right? No, not always. It may be important to maintain a certain T level to which the body is used to (which would explain why certain athletes who tried to lower their T-levels usually performed poorer after T-depletion therapy). But several athletes have very low T levels despite being very 'strong' (weight lifting) and some transwomen athletes actually improved their performance after undergoing hormonal therapy. OK, but these are exception to the rules, correct? So banning women with higher T levels from competition makes sense, it gives them an unfair advantage? The question is: an unfair advantage to what? One athlete performer needs different skills compared to another. With few exceptions, there has been no consistent evidence that higher T improves performance across all disciplines. And we don't exclude very tall men from say the pole vault or sprinting, so why are we excluding women with a high T level? We don't boost men's T-level if it's in the lower levels, yet some extraordinary athletes have low T levels. Sometimes T goes up with physical training, sometimes it goes down. Why is it so complicated?

Why wouldn't it be? Why would strength and endurance depend on one molecule alone? Evolution would surely not risk putting all of its eggs into a single molecule, it would be too dangerous, too prone to error.

The truth is that as scientists we often become infatuated with a story. A simple, easy to tell story. A problem that I recognize as a practicing scientist. While stories are important and ease communication, they can also create dangerous myths that oversimplify a complex problem and - a lot more problematically - become weapons for institutionalized racism and sexism. It is disturbing to read about statistical hacking of data, cherry picking and post-hoc definitions of presumed T effects that have been employed in previous T-research for the sake of promoting a narrative. A sexist, transphobic and yes also racist narrative.

Sadly, some of the T myths are, as the authors put it, like a zombie: they won't die, no mater how much new better research tries to kill it.

Hopefully more research will be conducted in the future to explore the role of hormones derived from cholesterol (this includes testosterone, estrogen, progesterone) in human development and behavior. Because there is no doubt they're essential molecules for development (both physical and mental). Refusing to investigate the nuances of their effects can have harmful effects on everyone: from men, to women, to trans and non-binary people.

[Abby Outterson · Rating 5 out of 5]

This book came highly recommended by Alok Vaid-Menon, so I was excited to read! It was fascinating, but certainly did not offer any answers about T; instead, it demonstrated just how limited our view of T really is. By examining research and popular culture’s depiction of T’s role in various categories that include aggression, reproduction, dominance, parenting, and sports, the authors reveal how much society’s views of gender norms have informed the way researchers conduct and interpret T studies. The most striking examples were the wide use of “p-hacking” in study analysis and the horrifying consequences of “normal” t values for women in sports being strictly enforced (on non-western women, after data establishing those values came from western women only.)

The book’s lack of answers around T- only more questions- can make it a little confusing to read, but it is worth getting through to understand how little we really know about T, and how much we stand to rethink its role in our society before examining further. I was glad to see mention of some promising studies that seem to be remedying many past problems and offer hope for a new direction in this field of research. Also, I highly recommend watching Vaid-Menon’s interview on Instagram with one of the book’s author’s, Katrina Karkazis. It helped clarify several of the underlying points made in the book. Both book and interview are well worth revisiting in the future.

[Jo · Rating 3 out of 5]

This book started off with a lot of potential for explaining the misconceptions with testosterone as well as the known facts. However, somewhere along the way, the authors' use of complicated and ambiguous word choice, sentence structure, and prose led to the main message becoming incredibly confusing. I understand that testosterone is still not understood completely and the premise of this book was to point out scientific discrepancies, but it was also supposed to explain this clearly to readers. After reading this book, I still feel confused as to what is known fact regarding testosterone and what isn't. I am also confused on its function, use in society, and its overall characteristics. All I know is that there have been many studies that have made conclusions of testosterone that the authors proved completely false or significantly manipulated. I also caught a few grammar mistakes as well as typos, which I was not happy about.

[JC · Rating 4 out of 5]

I started reading this book after a classmate mentioned Rebecca M. Jordan-Young in a class I attended that was specifically focused on feminist STS. I took a long hiatus from it because course work took a stranglehold of my life, and returned to this book after submitting my last course paper recently.

This was a very fascinating book that explored the extent to which understandings (even scientific ones) of testosterone are socially conditioned and used to justify and reify existing dominant social constructions of race and gender. Whether its girlboss corporate feminists advocating for power-posing to produce more testosterone and help create more highly powered women leaders (read corporate oppressors), [spoiler alert: its bad science], to racist researchers trying to find a biological reason (like testosterone levels) for the racial distribution of crime statistics, very flimsy science being used to discriminate trans athletes, or blaming the ‘male endocrine system’ for ‘male aggression’ rather than socialization and bad politics, this book was a fascinating glimpse into how molecules become deployed in scientistic conceptions of the world, and how complicated our endocrine system actually is, in contrast to the persistent misconceptions of it that float about popular media (and even within scientific literature itself). There’s lots of engagement with STS literature in here also, which was neat to encounter. Very good section on J. Philippe Rushton (a racist asshole who was tenured for decades at Western) and how his theories became important to racist theorization of this hormone. There are a couple recently published articles in Science for the People, touching on Rushton and sociobiology that I've found particularly enlightening, and you can read them here and here.

I still have such a bad backlog of books to get to, but will be staying away from writing reviews this weekend because I have a conference paper that I have to present on Monday, and I’m still not finished!! I have a persistent cough that is keeping me at home, which is possibly a good thing, because I have been stuck at home for weeks and am itching to get out, but also need to get this conference paper done! But also this cough is not doing me any favours on Monday. Thankfully it’s a virtual conference, otherwise I would have had to miss it.

[Claire · Rating 3 out of 5]

Maybe it's because I listened to it but I didn't love this one. Started listening after listening to a podcast about sex testing in the Olympics which I loved. But this one was a bit too much, one too many studies and repetitiveness

[Simon Roe · Rating 3 out of 5]

I found the content of analyzing previous studies on testosterone plus the racism and sexism in our assumptions on T fascinating. However the introduction and conclusion were esoteric and the nature of the book’s arguments make it hard to understand the nuances of the conclusions made (but that might just be a me problem lol).

[Ivy Shack · Rating 3 out of 5]

Basically, any time you hear a simple answer for a wide variety of problems or achievements, it's a good idea to maintain a heavy dose of skepticism.

[Dino · Rating 4 out of 5]

3.75

[Luka Prelas · Rating 4 out of 5]

Important and eye-opening, regardless of how slow and dense it was to read.

[عمر الحمادي · Rating 4 out of 5]

ملخص هذا الكتاب أن هرمون الذكورة ليس ذكوريا بالضرورة... استطاع مؤلفتا الكتاب دحض ما يعرفه الناس عن هرمون التستوستيرون، فضلاً عن التشكيك في مدى ارتباطه بالقوة والهيمنة والعنف والأداء الر��اضي مستندين في ذلك إلى منهج نقدي لاذع للأبحاث الكلاسيكية التي ربطت بين مفاهيم القوة والرجولة والأداء وبين نسبة الهرمون المرتفعة... يستحق القراءة حتى لو لك يكن مقنعاً في بعض افتراضاته.

[Attabey · Rating 3 out of 5]

Sooo the TlDr is that Y is complicated and is hard to know what's going on... 🤷‍♀️

[Noah · Rating 5 out of 5]

I just wrote a 3-paragraph review on this book and how “real” and important this book is from both a social and scientific point of view, but then Goodreads decided to scrap it with an accidental screen tap. I am sad :(

Basically, I found it staggering that we understand so little about T, yet our biases and cursory knowledge about it impact so much about how we understand ourselves and the world around us. Every chapter shows another major human category affected by T’s scientific p-hacking and bias-confirming feedback loops.

This book gives me hope that we will eventually be able to recognize, deconstruct, and then repurpose the different types of T. Racism, sexism, and political agendas all have a firm grip on T, but as we poke holes, we should find a treasure trove of insight into ourselves and the forces which manipulate our understanding.

[Caroline · Rating 3 out of 5]

Challenging our notions of what testosterone really does, this book is also a great guide for how to examine research. What biases do the researchers/subjects bring to the table? Who is involved? What is p-hacking and how does create false results?

There are times that this book can feel dense/repetitive, but overall it provides a great deal of new information from biological and sociological perspectives. I especially recommend this book to people interested in how myths surrounding testosterone promote beliefs around race and gender.

[Ahmed · Rating 2 out of 5]

رغم ان البحث الذي يتناوله الكتاب ممتاز ومثير للفضول الا ان الطرح او السرد التفصيلي يجعل من قراءة هذا الكتاب نوع من الفضول الممزوج بالملل خصوصاً ان اغلب فصوله هي نقد للدراسات التي اجريت على هذا الهرمون مما يجعل قراءة نقد عن الدراسة عملية مملة ومرهقة.

الكتاب كنت اعتقده يناقش مسألة التيستوستيرون علمياً لكن بعد التدقيق اكتشفت ان هو يناقشها علمياً لاغراض سياسية وانا ما كنت مهتم لقضايا الهرمون السياسية.

[G · Rating 4 out of 5]

Really fascinating read about how culture/social expectations shape the way in which scientific experiments are both conducted and read.

[Jacob · Rating 5 out of 5]

"[Testosterone] is a transcendent, multipurpose hormone that has been adapted for a huge array of uses in virtually all bodies" (206).

This was a fascinating read.

Jordan-Young and Karkazis meticulously trace the stories we tell about T through a feminist studies of science lens.

They explore these stories in chapters each focusing on a different realm: the methodological issues around T research; the role of T in ovulation; violence; power and confidence; risk-taking; parenting; and athleticism. They chose these as realms where the claims about T are and have been especially impactful, socially and politically.

On the whole they show that we know a lot less about T than we think we do, and that much of the research on T is deeply methodologically faulty and tainted by racist, classist, and sexist bias. Much of this research seeks to reify what we already think we know about T, and its supposed links to virility, masculinity, and strength.

Testosterone is not fixed. For people of all sexes, T fluctuates throughout days, years, seasons and in response to specific activities and social stimuli (28-9). T also doesn't work on its own. It is generally bound to other hormones or to proteins (30), and how well your body can use it is affected by the number and location of your androgen receptors (31, 171-2). So somebody might have really high T levels, buu that's because their body isn't very good at actually using it. In fact T is often described as "sex hormone" but really isn't; there are multiple hormones that produce masculinizing effects, and T has many different functions (likely including many we still don't understand) in all bodies (41). All of this makes it really difficult to research T and its effects on its own.

Given scrutiny of the available evidence, most of the commonly held beliefs about T don't hold up. The two that stuck out for me most were around aggression and strength as these are both mobilized in the current war on trans women/trans feminine people (and also against Black men and Black women, the latter of whom are often rhetorically framed as having higher testosterone or being more like men whether they are trans or cis).

Double blind placebo controlled trials show absolutely no connection between T and aggression (56) and research that does show this starts from a racist, classist and sexist premise, then manipulates the data to reinforce what is already believed (as detailed in Chapter 3).

The chapter on athleticism (Chapter 7) was especially relevant as I was finishing reading the book during the Olympics and watching all of the controversy around racialized women athletes whose sex/gender came into question. As the authors put it "it's far too simplistic to say that testosterone is the single most important determinant of athleticism" even though testosterone is what competitive athletic sex testing in women's sports (unclear to me if men are ever tested??) has focused on.

Introducing exogenous testosterone is well documented to increase muscle mass, strength, and endurance. However, studies of T levels in elite athletes have failed to show consistent correlation between T levels and athletic performance (161). As the authors put it "strength is not generic." Different kinds of athletic tasks require different kinds of strength. T only aids with maximum and power measures of strength, and is actually negatively correlated with endurance. A study of youth competitive weight lifters showed that lean body mass is actually a better predictor of performance than T levels in both girls and boys (169). Furthermore, progesterone also has anabolic effects, and can make up for lower T in women (171). In short, T and strength *are* related, but in complex ways not easily measured in bodies shaped by different genes, environments, training regimens etc. (174) let alone across different sports that require different kinds of strength.

Similarly, T does affect libido, but the relationships are similarly "complicated and limited" (211) with decades of pharmaceutical experimentation showing that exogenous T isn't a reliable way to increase libido regardless of gender. The increased libido trans masculine people and trans men experience when taking T is likely mostly placebo effect (knowing you are taking T and its supposed to increase libido) alongside other physical and social changes that effect how you feel (212). T is a "social hormone" as the authors repeatedly remind us, and it can't be separated from the many other factors that effect the given realm, whether strength, libido, confidence, or aggression.

My only criticism of the book is the lack of attention to non-binary genders. For example, ovulating people are described as women, and people assigned female at birth who take testosterone are blanket-named as trans men. I would have liked more nuance in the language used around gender when relating it to sex, because as I know these authors know, sex ≠ gender!

Nevertheless, would highly recommend this book to anyone interested in exercise science, popular science in general, feminism etc.