Here is an interesting article on T!
The Many Gendered Hormone
by Natasha Mitchell
Footy final season is with us again with more than enough grunt and muscle to go around. The big boys are on the loose and the testosterone is raging. Or is it?
Testosterone is a hormone with quite a personality. Tainted by a history of abuse by bodybuilders and athletes, testosterone is often pointed to as the cause of aggression, bulging pectorals, an insatiable sexual appetite and the almighty hairy chest. Its reputation has been somewhat two-faced. Since the 1940's, the illegal use of testosterone and its relatives, anabolic steroids, to increase muscle mass and enhance sports performance has fuelled a blackmarket worth millions. On the other hand, its fruits of virility and strength have been well-accepted in more mainstream clinical therapies.
As the primary male sex hormone produced by the testicles, testosterone tends to be identified with all we stereotype as masculine. It's a lot to ask from a simple chemical arrangement of carbon rings, a derivative of the molecule cholesterol. Is it more than a humble hormone can bear???lt;br>
...testosterone tends to be identified with
all we stereotype as masculine
How much of our behaviour is controlled by the biology of our hormones? Does testosterone really make the man? It's a debate that's been waged in scientific and social circles for decades. Some have attributed high levels of testosterone to criminal tendencies whilst others call it the hormone of desire.
Amidst the excitement, what's emerging is that it's difficult to box our hormones so succinctly according to gender. Despite popular belief, testosterone is a many-gendered hormone. It belongs in the hormonal kitbags of both men and women, and can play a role in the well-being of us all??le, female??anywhere in between. Nevertheless testosterone should perhaps be best known as the "value-laden hormone", caught in a confusing web of social expectations and gender stereotypes.
The Big T through the ages
Before testosterone hit the collective consciousness, scientists had an inkling that the testes offered something special. In 1889, Charles ?ouard Brown-S?ard, a French physiologist concocted a 'rejuvenating therapy for the body and mind'. His bizarre elixir was a liquid extract made from the testicles of guinea pigs and dogs. Brown-S?ard claimed his juicy liquide testiculair increased his physical strength and intellectual prowess, relieved his constipation, and get this, lengthened the arc of his urine.
Centuries before, in a quest for the Viagra of the ancients, testis tissue was recommended as a fix for impotence. From aphrodisiac to medicinal marvel, the unsuspecting balls were destined for fame.
For his early testicular adventures, Brown-Sequard has been coined one of the founders of modern endocrinology.
Our endocrine system helps maintain the steady state of our bodies. It controls our metabolism, growth and reproduction, and helps us adapt to stress and changes in our physical circumstances. It also regulates the concentrations of important substances in the blood, like glucose, calcium, sodium, potassium and water. Secreted by various endocrine glands throughout our body (and some by the neurons, or nerve cells, in our brains), our hormones act as chemical messengers. They are transported by our blood to target tissues, where they activate a change in some physiological activity. But only if the tissue contains the right receptors. For example, for testosterone to have an effect on a particular part of our body, there must be testosterone receptors awaiting its call. It's a case of needing the right key for the right lock.
Years of often extraordinary investigations culminated in the production of synthetic testosterone in 1935. The success of Butenandt and Ruzicka earnt them the 1935 Nobel Prize in Chemistry. And so, the modern persona of this hefty hormone was launched.
Testosterone is one of a family of hormones called androgens. Best known for their masculinising effects, androgens first kick into action during the embryonic stages of life. To explain, let's go back to the prudish basics of reproduction biology. An embryo is conceived when a female egg is fertilised with a male sperm. The egg and sperm each donate a single sex chromosome to the embryo, an X chromosome from women, and an X or Y chromosome from men.
If the combination of these sex chromosomes is XX, then the embryo will be female. If it's XY, the embryo will be male. Though in fact, it's not until the sixth week of development that XX or XY embryos are anatomically defined. Before this the human foetus is essentially sexless, possessing a set of "indifferent" genitalia. One interpretation of this is that all embryos begin as female. Testosterone makes the difference, influencing the growth of male genitalia, while the female component of the indifferent genitalia degenerates. But is it only the absence of foetal testosterone that causes an embryo to develop in a female direction? It's a question that we know less about.
According to some, the intimate association between testosterone and male identity starts this early. Anne Fausto-Sterling , in her book, Myths of Gender, believes this inference that "testosterone equals male", while "absence of testosterone equals female", is well-entrenched in the layers of our culture as a notion of "female as lack", and that "such rock-bottom cultural ideas can intrude unnoticed even into the scientist's laboratory".
A girl's hormone too
Testosterone is also well known for its role in the hormonal hotbed that is male puberty. It promotes the growth of the reproductive tract, increases in the length and diameter of the penis, development of the prostate and scrotum, and the sprouting of pubic and facial hair. As well as these androgenic, or masculinising effects, testosterone also drives anabolic, or tissue-building, changes. These include thickening of the vocal chords, growth spurts, development of sexual libido, and an increase in strength and muscle bulk.
There's no denying these powerful physical effects which continue well into adulthood, and their driving force, hormones. But we feel compelled to box our hormones resolutely into those that belong to men, or to women. Estrogen and progesterone are the so-called female sex hormones, and testosterone, the so-called primary male sex hormone. With that we assign our hormones impossible gender roles. But of course gender ain't that simple, and nor are our hormones.
It turns out men and women produce exactly the same hormones, only in different amounts. Men's bodies generate more than twenty times more testosterone than women, an average of seven milligrams per day. Women, via mainly their ovaries and adrenal glands, make a tiny three tenths of one milligram of testosterone per day (1). But it may come as a surprise to know that women's ovaries primarily produce testosterone, from which estrogen is then made. This ovarian production accounts for one-quarter of the total circulating testosterone in a woman's body. Conversely, men's bodies produce their own all-womanly estrogen, converted by their tissues from their all-manly testosterone.
Psychiatrist Dr Susan Rako, believes testosterone is as much a woman's sex hormone as it is a man's. She argues that the "amount of testosterone, tiny as it is, that a woman's body is continually producing is an essential amount." Rako's book, provocatively titled, The Hormone of Desire, is one of a growing wave of publications about the importance of androgens like testosterone to women's health. In calling it the hormone of desire, Rako maintains "testosterone is the hormone most critically implicated in the maintenance of libido, or sexual desire, in women just as it is men".
Its major job starts, as with boys, at puberty. Think of short-and-curlies, hairy armpits, sprouting breasts, and angst about acne. Testosterone is a culprit. But we sure miss it when it's not around.
for many women there's the fear of side effects...
will I grow a beard?
As women age, their levels of circulating testosterone gradually decline. The effect can be especially felt in women around their menopause, when they also experience a precipitous drop in estrogen, or if their ovaries are removed, which prematurely induces a 'surgical menopause'. Rako says the symptoms of a "deficiency" or loss of testosterone can include a loss of vital energy and feeling of "well-being", a loss of familiar levels of sexual libido, sensitivity of nipples and genitals, and a thinning of pubic hair. Other impacts may include a "flatness" of mood, dry skin, brittle scalp hair, and loss of muscle tone and strength. It's understood that testosterone also contributes to the health of a woman's vulva, regrows the vital tissue of the clitoris, and can play a role in curbing osteoporosis by helping maintain the density of our bones. And if that wasn't enough, it can influence our cognitive function as well.
It's an impressive compendium of symptoms, supported by an emerging body of scientific research (based on clinical trials of postmenopausal women). Not all women experience these effects. But for those who do, the option for testosterone replacement therapy is available, for both women and men. There's the choice of patches, pills or implants - each with their own risks and benefits.
For many women there's the fear of side effects. Will I grow a beard? Will I sprout pimples? Will I become as randy as a rooster? Will I bulk-up with big boy muscles? Rako believes the resistance to prescribing supplementary testosterone for a woman with symptoms of deficiency "boils down to a rigid holding to the irrational notion that testosterone for women is unnatural".
Dr Susan Davis, Director of Research of the Jean Hailes Foundation in Melbourne, is one of a small group of scientists worldwide conducting clinical trials into androgen therapy in women. She says the aim is to keep the levels of testosterone within the normal blood level range for a younger woman. The idea is not to make women super-sexual, but to tailor the therapy to individual needs.
As with standard hormone replacement therapy (HRT) for menopausal women, testosterone is not without its strong critics. Unlike HRT, which combines progesterone and estrogen, the research into the side effects of testosterone therapy is relatively young. And should women expect the sexual vibrancy of their youth to last forever? Debates aside, one wonders why we hear so much about progesterone and estrogen in women, but very little about the oh-so-sexy testosterone?
Davis says we have a tendency to accept that men can be sexually active well into their 60s, 70s and 80s. But older women are rarely thought of as sexual, or supported in maintaining their sexual libido. Some say it's a tradition entrenched in an unsympathetic medical profession.
So is testosterone the solution for all women who want saucier sex-lives? Is our libido only titillated by testosterone? Of course our sexuality and libido are affected by much more than our biology. Let's not forget stress, boredom, anxiety, disinterest and exhaustion. But Rako argues "the wipeout of sexual desire that results from a critical reduction in testosterone is different from the fluctuations we experience with the various ups and downs of life and relationships."
Mirror, Mirror on the Wall, Who's the Most Aggressive of Them All?
Boys will be boys. You could cut a knife through the air the testosterone levels were so high. The 'roids were raging, goin' off, peaking, on a roll, out of control, over the top??ghty big men with mighty big hormones, hard yacka and all that...
It's not surprising that our levels of testosterone are understood to affect our behaviour. Testosterone receptors are found in our brain, which means the hormone interacts and binds with our neurons, relaying to them important messages for action. Deborah Blum, author of Sex on the Brain, says this indicates the brain is "prepared to listen to what testosterone has to say" and that "most researchers consider this at least indirect evidence that testosterone is capable of altering the brain, and thus, influencing our behaviour."
Before the last decade, much of the work into testosterone and behaviour was through animal studies. Examples reported by Blum include: Stanford University scientists found female rats, given testosterone at birth, not only developed penises, but "knew" how to use them. At Emory University's Regional Primate Centre, watching other monkeys have sex was found to boost male monkeys' testosterone levels by some 400%. Rose et al found that more dominant adult male rhesus monkeys had higher levels of free testosterone, which fluctuated if levels of dominance or social rank changed.
Professor Robert Sapolsky author of The Trouble with Testosterone, recounts the leg-crossing, knife-wielding 'subtraction' experiment. "Remove the source of testosterone in species after species and levels of aggression typically plummet. Reinstate normal testosterone levels afterward with injections of synthetic testosterone, and aggression returns."
Finding human subjects for research into hormones and behaviour is less complicated than it used to be. Gone are the days of liquidising tonnes of testicles, or taking awkward urine samples from self-conscious punters. Today it's as easy as a 'hook-tooey' into a specimen jar. At a given moment, a person's blood levels of free testosterone can be accurately measured from a sample of their saliva.
This simple spit test has allowed research to leave the lab, and enter the real world of raging hormones.
Professor James Dabbs of Georgia State University leads research into the relationship between testosterone and human social behaviour. To do this, Dabbs says "we need to know what happens in natural settings outside the laboratory?? have gathered data in settings ranging from bedrooms to barrooms, among subjects who include children, adults, unemployed day labourers, lawyers, prisoners, politicians and two chimpanzees." He's ventured into fire departments, construction sites, colleges, strip clubs and sports arenas.
Over the past decade Dabbs and his colleagues have found testosterone levels to influence a person's tendency towards criminal violence, delinquency, suicide, heroic altruism and aggression, as well as their cognition, sexuality and sex roles, occupation, personality, emotions, competitiveness, childhood behaviour, facial expressions, disturbed relationships and more. It's an extraordinary body of work with powerful implications.
As with most of our hormones, blood levels of testosterone vary according to our stress levels, or other demands on our bodies. As well as providing fabulous fodder for research, this presents a dilemma for scientists. For example, it appears a correlation exists between levels of aggression and testosterone. Sapolsky asks, is it (a) high testosterone that elevates aggression or (b) aggression that elevates testosterone? According to Sapolsky, the bias of endocrinologists is towards (a), when in fact (b) is the answer. It's one for the chicken and the egg. Do our actions control our hormones, or do our hormones control our actions?
Take testosterone on the sporting field. Dabbs' team took saliva samples of male fans before and after a televised World Cup soccer match. Mean testosterone levels increased in the fans of winning teams and decreased in fans of losing teams. The conclusion was that testosterone levels rise and fall with experiences of success and failure in social encounters. Other contests analysed included fights, tennis tournaments or chess matches.
Take testosterone in a prison. Dabbs' team found that criminal violence and aggressive dominance among women in prison is linked to higher levels of testosterone. An earlier study of male inmates found testosterone levels to be highest among male inmates convicted of violent crimes such as rape, murder and assault. Variables such as age, social factors and other hormones were seen as important in these studies.
Take testosterone and 'delinquency'. Comparing college students with men and women of similar age in a "delinquent urban subculture" (identified as skinheads, bouncers, bartenders, strippers), "delinquents" had higher testosterone levels than college students. (Personally, boxing the range of research subjects into a "delinquent urban subculture" sounds questionable, but anyway...)
Take testosterone in the workplace. Dabbs' team examined the salivary testosterone in seven vocation groups of men, as well as an unemployed group. They found that actors and footy players had higher levels than religious ministers. Dabbs related testosterone to dominance and antisocial tendencies, which in turn, he suggests, effect vocational preferences in subtle ways. Other studies reveal traditional 'white collar' workers possess lower testosterone than traditional 'blue collar' workers.
These results, and the multitude of other bizarre correlations made by Dabbs and his colleagues, appear conclusive. Hormones play a big part in the individual differences and day to day changes in our behaviour.
However we should be wary of blaming our way of being solely on our hormones. There's definitely more to our life equation than our endocrine system. Dabbs agrees that "to understand human nature, it is imperative to understand both biologic and social forces." But "behavioural or biological approaches are incomplete??tosterone affects behaviour, but the outcome of behaviour also affects testosterone levels." Similarly Sapolsky comments "our behavioural biology is usually meaningless outside the context of the social factors and environment in which it occurs."
...there's more to our life equation
than our endocrine system.
Deborah Blum agrees "there's a lot of quick political reaction to theories about a cause-and-affect role for testosterone in competition and aggression." "Feminists become understandably annoyed by the oversimplified, back-to-the-kitchen notion that women don't have the hormonal underpinnings for competition. And plenty of men - masculinists, if you like - are equally annoyed at being dismissed as a bunch of naturally bad-tempered apes." But Blum firmly believes "the connections between body chemistry and behaviour deserve our attention."
Valerie Grant, a behavioural scientist at the University of Auckland, would agree. She's states testosterone is the "biological underlay of dominance", and has just written a book that's ready to raise temperatures. In Maternal Personality, Evolution and Sex Ratio, she examines evidence that mothers have control over the sex of their infants. The suggestion is more dominant women are more likely to conceive boys. It's implied that a woman conceives an infant of the sex she is psychologically most suited to raise. "Her body, her personality and her behaviour are all appropriately tuned for the conception of a male or female infant". Defining dominance is an exercise in itself. Grant distinguishes it from aggression, and draws upon words like 'strong', 'influential', 'bold', 'powerful' in painting a picture of its meaning. This maternal dominance hypothesis raises complicated and contentious questions, about sex selection and the future of our population.
Grant asks should we go with nature instead of against? She agrees that we should "treat men and women with equal respect and dignity" but says we should "acknowledge the existence of biologically based, physical and psychological sex differences". Grant questions the "reluctance of women to stop trying to compete with men in those areas where men are known to be biologically advantaged, and to begin to explore those areas in which women have the biological advantage." It's biological determinism at its best. Controversial stuff, that may have some writhing uncontrollably in their seats.
Biological versus Social Determinism - No One's a Winner
All hail the mighty testosterone? Anne Fausto-Sterling, geneticist and author of Myths of Gender, has a problem with correlating our behaviour with a single hormonal state. She says "it's easy to forget that our bodies have a number of different hormonal systems, all of which interact with each other??attribute a change in behaviour to a change in a single hormone, when many different hormones rise and fall simultaneously, misrepresents the actual physiological events."
Some would see her considered critique as an attempt to restrict science's investigation into the biology of our behaviour, or to ban research into sex differences. But Fausto-Sterling is arguing "for a more complex analysis in which an individual's capacities emerge from a web of interactions between the biological being and the social environment."
Ultimately she's reminding us that the science we do is never value-free. Despite claims of objectivity and neutrality, everything we do is clouded by the subtleties of our socialisation, of our life experience. What we don't see, we ignore. What we see too well, we may forget to notice too. Testosterone and gender stereotypes can be too familiar, or altogether unfamiliar, depending on where one stands. It's difficult for science, and its pursuit, to exist in a social vacuum.
Fausto-Sterling adds, "by definition, one cannot see one's own blind spots, therefore one must acknowledge the probability of their presence and provide others with enough information to identify and illuminate them?? ought to expect individual researchers will articulate - both to themselves and publicly - exactly where they stand, what they think, and, most importantly what they feel deep down in their guts about the complex of personal and social issues that relate to their area of research."
Food for thought in these balmy hormonal times.