Farid
Gazizov
Impact
of evolution on human thought
Testosterone
For a long period
of time humans could not answer the question of what makes a man, a man, and a
women, a women. As was recently found
main difference is not just in presence of genitals. Probably one will ask why? The answer is that genitals themselves are
indirect products of another matter. The
name of this matter is testosterone.
"Testosterone is a hormone that
stimulates sexual development in male human beings. It belongs to a family of hormones called
androgens. Primarily the testicles, a
part of male sex glands, produce androgens.
The ovaries in females and the adrenal glands in both sexes also yield
small amounts of testosterone and other androgens (The world book encyclopedia).”
In its earliest
crucial functions, in developing embryo, testosterone play the key role in
telling the cells of the genetically male embryo to develop as a male. It is amazing, but all human embryo begins as
females for the first few weeks of an embryo’s life, a small group of cells
have potential to develop either as ovaries or testes. About one million of genes that are needed to
direct the development of a human being, one single gene (the "SRY” gene), which
is carried on the Y chromosome, is responsible for determining the sex of the
embryo. If the embryo’s cells contain
the "SRY” gene, the embryo will develop testes, which at some point and for a
limited period of time early in its development produce and release a big
amount of testosterone. It turn, testosterone then signal the cells of
other parts of the embryo to develop as a male.
As shown in the
study by a Stanford research group namely testosterone is responsible for
formation of genitals. An experiment was
held on newborn female rats. They were
injected with testosterone.
Surprisingly, but the female rats developed male genitals, and female
genitals began disappearing. Later
"converted” female rats started revealing purely male behavior, and they were
fully aware of usage of their "new” male genitals. The same experiment was performed with male
newborn rats. It is amazing, but their
penises withered and later completely disappeared. This experiment is not ethical to perform on
humans, but random facts suggest that all most the same can be done with
humans. For instance, in lesbian couple,
butches (female that represents male) use testosterone injections to develop
male features such as deep voice, facial hair and muscles ("The He Hormone,”
Andrew Syllivan)
In girls, the
adrenal glands begin to produce testosterone earlier than in boys. That’s is how and why girls mature earlier,
as a rule, than boys. It was
testosterone that stimulated the growth of girls pubic hair and underarm hair
(there are testosterone receptors in the skin of the pubic area and the skin of
the underarm that are genetically programmed to react to testosterone by
producing hair). And testosterone
stimulated girls skin to produce more oil, contributing to the acne of girls
early teenage years, but also to the healthy glow of the skin and the shine of
the hair.
The medical book
Reproductive Endocrinology by Drs. Samuel Yen and Rovert Jaffe, states; "Testosterone and other androgens have some
biological activity o virtually every tissue in the body.” Among the most important functions listed are
"anabolic actions, such as stimulation of linear body growth, nitrogen
retention, and muscular development.”
This statement means that testosterone works to keep the cells of the
body functioning efficiently, making the best use of nourishment of growth and
maintenance, and particularly contributing to the health of bones and
muscles.
Having knowledge of the way
testosterone function in the body, artificial testosterone injections can be
used for variety of purposes. One of the
purposes of artificial use of testosterone is to stimulate sex drive. The balance of this hormone is responsible
for initiating and maintaining the production of sperm from early puberty
throughout adulthood in male body.
During childhood and adolescence, these hormones are responsible for:
1) Growth of
genitals
2) Depth of pitch of
the voice, increase muscle mass, and growth of bones.
3) Appearance of the
body and facial hair.
Overproduction of
testosterone caused by testicular, adrenal, or pituitary tumors in the young
male may result in precocious puberty.
Overproduction of testosterone in females, caused by ovarian and adrenal
tumors, can result in muscessation of the menstrual cycle and excessive growth
of body hair. Level of testosterone are
low before puberty; they begin to increase at the onset of puberty and continue
to increase during adulthood. Production
begins to diminish at about age of 40, eventually dropping to about one-fifth
of the peak level by age of 80 ("Hormone of desire,” Susan Rako).
Scientifically established men’s testosterone, level is at least ten times
higher than any of the women. According
to the last available date, even male population accounts for less than 50
percent of the world’s population, major part of violence is perpetrated by
men.
Currently many males use
testosterone shots or gel for the purpose of body-building. Testosterone shots trigger imbetterment of
appetite and muscles growth. Besides,
testosterone can have effects on the function of several brain areas. One additional surprising effect of
testosterone is that it can not only affect the function of the brain but also
its development and anatomy. Study in
laboratory of Roger Gorskis at the University of California, Los Angeles, has
revealed that the sex difference in the brain anatomy appears to be due to the
presence of male sex hormones at a certain stage of brain development in male
rats. Later work has shown a similar
effect of testosterone at other brain areas:
for example, the spinal nerve cells that control the muscles of the
genital area are more numerous in male rats (cross sections through the
hypothalamus of a male and female rats (male, (thinner and longer)).
Below is a human life
example how hormone level can influence human health, and behavior brought by
John K. Young in his book "Hormones; molecular messenger.”
"Bridget was divorcing Bob, her husband of tem years, so she was not
terribly surprised when she started to feel anxious and upset upon awakening in
the morning. She grew worried, however,
when these anxiety attacks became more frequent and stronger, coming upon her
at all times of the day. She went to
see a psychiatrist. The doctor also
assumed the problem was stemming from her divorce proceedings and prescribed an
antidepressant. After two weeks of more
anxiety and no relief coming from the dedication, Bridget felt like committing
herself to a institution. Her
nervousness was now even making her hair fall out; her skin began to feel thin
and bruised. She was not eating
properly either, but was surprised to see she had lost over twenty pounds.
One night Bridget’s best friend Virginia invited her to a dinner
party. Over the meal, someone mentioned
how traumatic divorce was; Bridget laughingly said that it was not making her
thin and anxious, it was also thinning out her skin and hair. One of the other guests, a young woman, asked
her to elaborate, and Bridget shyly told her the symptoms she had been
suffering from. The young woman then
introduced herself as a doctor. She
asked Bridget to come down to her office for a few tests. Bridget did and these tests revealed what the
doctor had first suspected; that Bridget was not suffering from a psychiatric
disorder, but rater a hormonal one. Her
thyroid gland was overworking, giving her the symptoms of thinning hair, thin
skin, excessive weight loss, and anxiety.
Afte4r treatment all of Bridgets’ symptoms disappeared.”
The example
described above suggests that level of testosterone influence not only physical
development of the body, but also is responsible for emotions and
behavior. One researcher, curios about
the fact that only male canaries sing during mating season, gave a testosterone
shot to female canaries. The result was
amazing, the female canaries "burst into song.”
The same experiment was performed on zebra finches. Dr. Christina Wang’s study reveals that men
with low testosterone level are irritable and aggressive than those with
high-normal level. "When their
testosterone level was increased during hormone-replacement therapy, their
anger diminished and their sense of well-being increased.”
Robert M.
Sapolsy, in his book "The trouble with testosterone,” takes opposite opinion
side to scientists who think that increasing testosterone level leads to
changes in behavior (such as becoming more aggressive). He holds an opinion that changes in
surrounding environment trigger change in the level of testosterone.
"Okay, suppose you note a correlation between levels of aggression and
levels of testosterone among these normal males. This could be because (a) testosterone
elevates aggression; (b) aggression
elevates testosterone secretion; (c)
neither cause the other. There is a huge
bias to assume opinion (a), while (b) is the answer. Study after study has shown that when you
examine testosterone levels when males are first placed together in the social
group testosterone levels predict nothing about who is going to be
aggressive. The subsequent behavioral differences
drive the hormonal changes, rather the other way around ("Trouble with
Testosterone,” pp. 152).”
It is a good
point, but what about evidences suggesting that men after taking testosterone
injection find themselves more aggression than normally. The article "The He Hormone” by Andrew
Sullivan brings a good example when a man after taking testosterone shot could
not control his increased aggressiveness and "had nearly gotten into the first
public brawl of his life.”
"Soon after I inject myself with testosterone I feel a deep surge of
energy. My attention span shortens. My wit is quicker, my mind is faster, but my
judgement is more impulsive.”
Several other studies suggest that individuals with
winning attitudes have higher testosterone levels, at least for a short period
of time, than those without such an attitude.
One group of researchers, for example, measured testosterone levels in
six college tennis players and found that testosterone levels began to rise in
all of them before their matches, apparently in anticipation of competition. The big surprise came after the fact: the testosterone levels of those who won
their matches remained high, while the testosterone levels of those who lost
diminished.
A second group of researchers, at North Dakota State
University in Fargo, undertook even further step by trying to figure out if it
was the competition itself, or the mood produced by winning, that caused the
rise in testosterone. In their
experiment, male college students either won or lost $5 through a series of
coin tosses. The task removed all
elements of skill or competition; blind luck determined winners and
losers. After the tosses had been
finished, the researchers measured the saliva of participants for changes in
their testosterone levels. Those who won
money experienced a more positive mood and a rise in "test”; those who lost
whose a decrease in the later. The
result suggested that the acts of winning, rather than the nature of the
competition or the skill involved, improve mood and produces an increase in
testosterone levels. This experiment
obviously supports Robert’s Saporky statement that testosterone level changes
with external factors.
Two more recent studies by a single group of researchers
went further to find out if one has to directly participate in competing in
order to experience increase in testosterone level. In the first study, the
researchers measured the salivary testosterone levels of fans who attended a
college basketball game. In another,
they took the same measurement of a group who watched a World Cup soccer match
on television. In each study,
testosterone levels were taken before and after the game. In both experiments, those fans whose team
had won experienced a surge in their testosterone levels, while those fans
whose team had lost showed a drop.
The result was
very surprising. Even the fans are not
directly involved in the competition, the their testosterone levels change in
accordance with whether their team is losing or winning. The supervisor of the researches, a doctoral
candidate in education psychology at the University of Utah in Salt Lake City,
makes a comment on the researches notes:
"Fans do not have much to do with outcome: there are more like voyeurs
to the team’s experience of competition.” Nonetheless, experiencing victory
even vicariously apparently has very real effect on a person’s hormone levels.
Testosterone
level is not only different among individuals, but it changes within one
organism one intraday basis. Testosterone level can vary by up to fifty percent
during one day. In the mornings it tends
to be higher than in the evenings. This
is another reason why people feel fresh in the mornings. During the day one
might experience ups and downs of testosterone level induced by winning mood
effect. These up and downs do not have
effect on physical development of the individual ("The Testosterone Syndrome,”
Eugene Shippen, William Fryer).
Sensitivity to
the changes in the testosterone levels is not very researched subject. It is noticed that different individuals
experience different effects after having the same amount of testosterone
injected. The genetically determined differences in the numbers of testosterone
receptors may be one factor.
Besides
stimulating growth of bones, body mass, facial hair, change in voice,
testosterone might be a possible reason of illnesses. In the report by Paule A.
Lotufo, Joann E. Manson, Alexandersen P, Haarbo J, Christiansen C., on male
pattern baldness and coronary heart disease, the authors conclude that "vertex
pattern baldness appears to be a marker for increased risk if coronary heart
disease. They state that testosterone
may provide a "plausible explanation for an association between baldness and
coronary heart disease.” The reference
cited is a study that shows elevated testosterone levels in men with prostate
cancer and baldness; however, these were no measured testosterone
concentrations in the data presented.
Dr. Brian L.G. Morgan and Roberta Morgan, in their book "Hormones,” are
tying to link high testosterone level with coronary heart disease. They bring into attention the fact that in
general, since women have lower testosterone levels than men, according to
available poll of data, they live longer lives.
"Equal numbers for both sexes are around by age thirty, and only 70
percent of men reach age sixty-five, where as 84 percent of women do.”
On the contrary
recent results from the Telecom Study showed that decreased testosterone levels
were associated with increased cardiovascular risk factors in otherwise healthy
men.
Eugene Shippen
and William Fryer, in their book "Testosterone syndrome,” agree with the
opinion that low level of testosterone are more associated with increased
cardiovascular risk factors, rather than all the way around.
"The fundamental fact is this: a clear and ever-increasing majority of
medical studies report an association between high testosterone and low
cardiovascular disease in men. This is
not a coincidental association, since when testosterone is diminished
well-accepted risk factors increase, and when testosterone is administered in
appropriate doses most of the major risk factors for heart disease
diminish. Moreover, in the majority of
patients, symptoms and objective EKG measurements improve. These studies are confirming the results I
have been getting with patients for years.
Men prosper health wise and live longer when their testosterone levels
are normal. Heart problems, in
particular, are more easily controlled (The Testosterone Syndromes, pp. 81).”
With growing old,
men begin experiencing erective problems and losing sexual interest. These problems are caused by diminishment in
testosterone level. Facts reveal that
men who are taking testosterone, in any form, experience surge of sexual
interest, and overall enhancement in physical strength. Eugene Shippen, and William Fryer, in their
book "The Testosterone Syndrome,” relate diminishing sexual interest to a sign
of future heart disease and diabetes, conditions common in the male menopause
("The Testosterone Syndrome,” pp. 59)
At the end of
this research, I would like to notice and bring example of the fact that
majority of scientific world hold opinion that artificial testosterone if
correctly applied can bring much of good to the human kind, especially to
elderly.
"Standford R. is
seventy-four years old now, but he has had heart problems since the early
1970s. It did not make life easy for
him. He is an athletic man who likes to
hunt, fish on the river, and walk in the woods.
By the time Standford together with his chest pains, got into the 1980s,
it was time for a quintuple bypass. The
chest pains started up again in a few years later. His chest pains went away, his energy
returned and when he is not walking over the hills and fields and hunting in
the woods, Standford makes love.
Sometimes twice a day ("The Testosterone syndrome,” pp79).
Conclusion
As can be
concluded from all researches discussed above change in testosterone level
triggers changes in behavioral pattern, and environmental change followed by
change in behavioral pattern triggers change in testosterone level.
The arguments in
scientific world regarding testosterone and their role in human anatomy are not
over yet. The subject is hard to
explore, because experiments that has to be done in order to find right answers
are not considered to be ethical on humans.
The scientific world has no choice, but to use random historical facts
to come to the answers. However, the
fact the testosterone play a huge role in human development and behavior is not
argued by any more.
Reference:
1)
"The Testosterone Syndrome”;
Eugene Shippen, M.D. and William Fryer, M. Evans and Company, Inc., 1998
2)
"Hormones; Molecular
Messenger”; John K. Young, Franklin Watts, 1994
3)
"The Trouble with Testosterone
and other essays on the biology of the human predicament”; Robert M. Sapolsky,
Scribner, 1997
4)
"The Hormone of Desire; The Truth about sexuality, menopause, and
testosterone”; Susan Rako, M.D., Harmony Books, 1996
5)
"Never Too Buff”; John Cloud
6)
"The He Hormone”; Andrew
Sullivan