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Impact of Evolution on Human Thought. Testosterone

Impact of Evolution on Human Thought. Testosterone

Farid Gazizov

Impact of evolution on human thought


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


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


“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).


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.


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


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