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