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Topic Name: Does the brain have a sex?
Category: Genetic Engineering
Research persons: 4engr.com(Organized By variuos scientific resources)
Location: Changaon Residential Area , Bahadarhat, Chittagong-4000, Bangladesh
Details
To speak, count, locate themselves in space… As many aptitudes as one often
judges to separate men and women. Do these differences have they a scientific
reality? They in the brain are observed? True answers in example.
Cerebral volume and intelligence
A well exploited belief
At the XIXe century, the anthropologists are taken of passion for the brain,
this body until at the time completely ignored. Refuge of the heart, its weight
is regarded as the reflection of the intelligence. Thus to have a good idea of
which is more the crafty one, some, like celebrates it Paul Broca, launch out in
metric studies. Thus, in 1861, Broca analyzes 432 brains. Let us recall that at
that time the fashion is to be bequeathed this supreme body to science. It thus
weighs them in two manners: either directly once taken, or by filling the
brain-pans with shot. At all events, it is quickly that it succeeds in
confirming what it thinks already: the women are much less intelligent than the
men.
It is known as. But, let us recall all the same that the women are much less
tall than the men and than this only fact can justify a lighter brain. Yes, but
with XIXe, it is clearly allowed that the woman is definitely lower on the
intellectual level.
And in XXIe century?
Time passed since Broca and his/her colleagues anthropologists and science
evolved/moved. With it, techniques of medical imagery like the IRM, which are a
reliable method today, at least more than to calculate the volume of lead
returning in a cranium. In 2001, the results fell. The brain of the man has an
average volume of 1113 cubic centimeters and that of the woman reaches the 1022.
Even paid to equal size, the brain of the man remains larger. Then yes, the man
has a bulkier brain. Simple reflection of this sexual dimorphism which
characterizes almost all the animals and from which we do not escape.
Attention not all to be confused all the same. Yes is the woman has a “small”
brain more, but less powerful intellectually for as much? That amounts wondering
whether there is a bond between large brain and great intelligence, the size of
the cerebral body and the intellectual abilities. And well, there is no
relationship between the two. To have a head well done better than a quite full
head like one says.
The geniuses have sometimes small brains
The proof that it is not the weight of the brain which conditions the size of
the intelligence. One knows it today but for most difficult to convince, here
are some examples.
With XIXe, we saw it, the anthropologists are clearly with the mode with their
metric measurements, of cranium and the brain. Not astonishing whereas certain
large intellectuals bequeath to science their splendid cortex for studies. And
the results contradict a priori of Paul Broca. Thus, the brain of Anatole France
weighs only one kilogram, whereas the average weight of the brain is estimated
at 1, 350 kg. And the weight of the brain of famous Albert Einstein is 10% lower
than this average.
To summarize: it is not the weight of the brain which makes the genius. The
women do not have thus to redden of their cerebral capacity, slightly lower than
that of the men.
Invisible differences
If thus the volume and the weight of the brain do not make it possible to
differentiate the men and the women, which criteria to use? Since it appears so
natural that the brain is sexually marked, us should be able to observe it.
When science is baited
After the fanatics of the chronometry of XIXe and their failure, the scientists
baited themselves to find new markers justifying of the behaviors female and
male. Because yes, we act in different ways. And if the small girls are more
numerous to spend the hours to converse rather than to play foot, it is not for
nothing. The brain thus be reviewed.
First index, a particular core located in the hypothalamus, a gland of the brain
connected to the pituitary gland, a large center of production of hormones. As
in all the other mammals, this core appears appreciably larger in the male than
in the female. A good index? Not. Indeed, because we are unable to say to what
serves this small core and especially, certain women have, comparatively, a core
larger than certain men. In conclusion, if a brain alone is studied, without
having any index on the person to which it belongs, it is impossible to say if
it is about a male or female brain starting from this only evidence. What is
largely confirmed by the cerebral imagery: without preliminary index, one cannot
distinguish, sexually, two brains in activity.
And nothing proves…
After this new failure, other zones were observed: the callous body, the size of
the hemispheres right and left etc All was imagined. Only here is, no study
seems conclusive. And if science were mistaken in ground in study? Yes, men and
women are different from their behaviors, but the differences are not always
explained by biology. Our differences can simply result from a different
education. Our brain, with the birth, is only one soft wax which will be carved
by our trainings, our experiments, our education and our own reactions. We are
undoubtedly born, men like women, with a similar cerebral structure, which will
be specified according to our environments.
Really? Yes and not, because with the birth, the brain has well a sex and it
will keep it. Simply, the impacts of this cerebral sexualisation are very
largely fantasies.
But to check it, let us pass by again by only and single sexualisation of the
brain then let us begin again, with one, specificities of each sex in order to
see whether they are really marked by a cerebral characteristic. For that honor
with the ladies.
Sexualisation? Yes
Our sexual hormones and our behaviors, inter alia, are controlled by the brain.
Result or causes sexual reproduction, it does not matter. Here, the interest
lies in the fact that very early, at the embryonic stage, our brain receives
various sex hormones. In that only it is a sexual body.
A genetic and hormonal sex
At the first stages of the development, the sex of the embryo is marked, at
least genetically. You point out the famous difference: the women have two X
chromosomes whereas the men have an X chromosome and one chromosome Y. This
difference genetic is at the origin of the formation of the sexual organs which
very early are functional. Thus, they produce female or male hormones quickly.
Secreted in blood, they arrive at the brain of the fetus and thus act on its
formation. Thus, the sex hormones take part in the construction of the brain,
while influencing the establishment of various circuits of neurons. In that, and
that only, we can speak about the sexualisation of the brain.
All occurs in the embryo
The sexualisation of the brain takes place during the fetal life. It is the sex
which then determines the formation of certain neuronal circuits which play a
major part, well later, in the physiology of the reproductive functions.
It is talkative
It is too talkative, it is in fact what it often reproaches him. And it is true
that the women are much more loquacious than their male counterparts. They
pronounce, on average, 20.000 words per day whereas the men, them, say only
7.000 of them. During years, one found (false) pretexts biological to
standardize this difference. What says the neurosciences of them today?
The science of the rumor
The rumor runs since the Seventies that the women are much more gifted than the
men for the verbal tasks. Language earlier, more developed, more moderate, which
was not that a simple report in fact was tracked by the neurobiologists. And
here that in 1995, the proof in is supposedly made. Indeed, certain Sally
Shawith, very famous university of Yale, shows in one of his studies that, if
the women have the direction of the word, it is because their two cerebral
hemispheres are activated during this exercise. Whereas only the left
hemisphere, where the surface of Broca is placed, the zone known as of the
language, is requested at the men. To summarize, the language among women
requires the use of the whole brain and at the man right the left brain.
Astonishing. The brain is clearly lateralized. Approximately, the left side
manages the morality on the right side of the body and conversely. That there
are zones specific to the language, of agreement. But why, according to the sex,
these functions move whereas the brain is the same one?
The brain out of cause?
Thus with leaving the Nineties, the explanation given is that the woman
activates her two cerebral hemispheres during a linguist activity. And this
competence is due, according to the belief, with female hormones: estrogens. A
little runs like explanation… Blow, the scientists bait themselves to check the
wobbly assumption. Already while helping themselves of progress of the cerebral
imagery and especially by carrying out studies on more significant samples.
In 2004, a very large study, published in the American review Brain (vol.127)
finally taken stock: no significant difference is observed. The women do not
call more upon their two hemispheres at the time of the activities of word,
their brain functions exactly like that of the men.
Ladies, you do not delight too quickly. The basic report is always of
topicality: the women are much more talkative than the men. Simply, this
specificity is not due to a difference in cerebral operation. It is not a
question of a biological difference. The explanation is undoubtedly to find side
of the training. The small girls spend more time to papoter in the courses of
school than to defy itself physically. In some kinds, the women are more
solicited, and especially earlier, for the act of speech.
It can make several things at the same time
It can prepare the dinner while making the list of the races for the following
day, supervise that the children make their duties well and I pass from there.
The woman is multi-task. She can make various things at the same time. Contrary
to the man who is regarded as mono task, whereas during his evenings foot it
proves the opposite to us: it can look at, drink and eat at the same time. Let
us give up, good once for all, these exasperating stereotypes and artisan's.
A fiber network
To manage various activities into simultaneous means to call upon various
cerebral zones at the same time, therefore that the hemispheres right and left
of the brain exchange much. However, the two hemispheres are connected by
commissures, networks of nervous fibres. The callous body, which makes the
bridge between the two zones is most important of these commissures. It is
included/understood why then the neurobiologists sought side of this callous
body to explain why the women are able to make so much things at the same time.
During various autopsies, the scientists believed to see a significant sexual
difference in the thickness of the callous body: it would be thicker among women
than at the men. These results thus encouraged a great morphometric study
published in 1982. The results confirm the former observations and the
researchers protest at the time the thickness of the induced callous body of the
different behaviors at the man and the woman. When it is thick, it allows a
better intracerebral communication, when it is thinner, it forces the use of
only one cerebral hemisphere at the same time.
And here is the explanation given. Really? Not. To explain these
psychological differences with a so variable tool, appears doubtful.
The restored truth
This study alone obviously was not essential, even if it were very relayed by
the avid media to explain the differences man-women by cerebral architecture in
each sex. Thus, a great study resuming 50 studies undertaken during years 1980
and one new study relating to 2000 people in 1997, came to contradict these
facts. The new one? Yes. Not the least reliable index. The thickness of the
callous body is not more important at the woman. What to call in question last
measurements.
And then, moreover, is a large callous body really an advantage? Not. Because
to have a strong thickness of this commissure does not mean to have a nervous
fibre bridge more solid. This bond thus does not have any direction, just like a
large brain is not more intelligent.
Once again, these two behavior various associates with a sexualisation,
cannot be explained by biology. They concern more the behavior and also depend
on the company in which we grow and evolve/move. Traditionally, in our company
the woman assumes, and it is less and less true, the management of its
professional life and most of the domestic life. Accustomed to this rate/rhythm
since childhood, not astonishing that it keeps and develops this feature into
growing old. Today, the men answer these various tasks and a father with the
hearth, also, can make several things at the same time, even if he is a man.
It has intuition
Ah it (too much) famous feminine intuition… You know when a woman is persuaded
that you are not well because it “reads it” on your face, whereas you hold a
great form. Which cause invented for this new female phantasm? A gene, a
hormone?
Intuition, a myth?
The subject became almost amusing with force. On the base, one confers to the
women a kind of gift called the intuition. Thanks to this gift, the woman is
apparently able, better than any man, to interpret the unvoiced comments, to
read the expressions driven back starting from a simple glance, to detect a
problem with the least start of voice… But the feminine intuition is a myth. No
element in the female brain makes it possible to encourage such a lie.
However various causes are evoked
gene? Just like some seems to have discovered gene of the marital inaccuracy,
others would have found gene of the intuition. Forgery, even if information is
disseminated by the scientific reviews most prestigious.
hormone then! Either. However the sex hormones have good back. But no
characteristic hormonal activity forever recorded nor noted. Which other
argument?
Of the sensory sensors in the good place. More sensors and differently
placed. Here what could explain this intuition. Really? Not, that is impossible
of cerebral activity. If they are neither the genes nor the hormones the persons
in charge, it is necessary to seek elsewhere! And it is what certain scientists
did. In particular Dr. Ruben Gur, in 1980. It tried to connect the cerebral
activity of the women and the intuition. For him a report is essential: even at
rest, the cerebral activity of the women is very intense, approximately 90%,
whereas that of the men borders the 70%. Thus, women, because they are always
ready to react are much more sensitive to their environment, ready to leap and
to anticipate especially there. But once again, the study does not hold really
the road. If one had fun to replace the women and men studied in the Eighties by
active women and current fathers with the hearth, or quite simply if one sought
the phenomenon in other companies, we would certainly not obtain the same
results.
The feminine intuition can more be explained socially, by the training. In
our companies, they are the small girls who play headstock, the teenagers who
keep children. In short, the women are rather quickly put in contact with the
other and they learn how to include/understand it and anticipate its reactions
precociously. Just like the maternal instinct, the intuition is a kind of price
gained while growing. What is less and less true in our companies where both
sexes tend to fill the same tasks.
It has a GPS integrated in the brain
Let us pass to Him maintaining. Ladies arrange these roadmaps which you cannot
still read correctly and let you guide by the incredible direction of the
orientation of the male. But it is time to say it: if the men have sometimes
this quality to locate themselves well in space it is not, for as much, an
innate capacity.
Two brains
It was necessary to find them well a cerebral specificity justifying of this
aptitude for better locating itself in space. What could be more natural than to
find during left brain of the women? And well it is while seeking that one
finds. When it is thought that the women have a facility for the tasks
linguistics, it is very natural to think that the men locate themselves well in
space because their right brain is stronger.
Return behind. This theory which under hears a strong specialization of the
cerebral surfaces is the theory of the two brains. An old belief taken again by
three important neurologists of Harvard: Geschwind, Levitsky and Galaburda. For
them, each hemisphere of the brain plays a role well given. The left brain is
requested for the activities of language and rational thought, while the right
is the seat of the emotions and… of the representation of space. Here it is the
this so much rented male talent.
Why such a theory?
Quite simply starting from the lesions sometimes observed. For example a lesion
in part of the left brain makes lose the word, from where: the word is placed in
the left hemisphere. Some notice that lesions with the right brain induce losses
of capacity to be directed and blow, the right brain becomes the seat of the
orientation. But attention, an injured zone highlights the part which it plays
in a function but not the fact that it is essential for him. At all events, this
simplistic vision of the cerebral organization allured a very large audience.
A true cerebral specificity?
Then yes or not, are the men equipped with a brain larger right? Not. And the
cerebral imagery largely contributed to destroy this theory of the two brains.
The men and the women have equivalent brains, which function at the same
rates/rhythms. Moreover, it is inconceivable to think today that a brain is
affiliated with such or such function. That it is for the language or the
location in space, it is all the brain which is active, not a part only. Each
function calls upon various zones.
Despite everything, we are forced to admit that, in our company, the men
often have a better direction of the orientation than the women. Undoubtedly
parce, very young people, they are more confronted with exercises which require
of good knowledge to be located in space: race of orientation, football,
basketball… But the girls who practise these same activities develop this same
capacity. It is although the direction of the orientation is acquired by the
training.
It is strong in maths
The men are more gifted than the women for the scientific dies. In any case, it
is what affirmed former president d' Harvard, Larry Summers, during a speech.
Normal that this aberration cost him its place. Because not, the men are not
programmed better to excel in these fields.
To forget the two brains
And yes logic. The aptitude for mathematics was placed beside the direction of
the orientation, in the right brain. Which chance for the men, at least on
paper… We saw it, the theory of the two brains is false thus impossible to give
this so-called scientific talent to the brain highly developed right.
And to forget the hormones
Assertions fraught with consequences and especially completely false. The use of
the cerebral imagery made it possible to give a progress report on this question
by showing the activity of the male and female brains at the time of the
activities of calculation. The result is very different. It was supposed that
only the right brain was in activity. It is the opposite. Arithmetic calculation
requests the left frontal cortex and the left and right parietal surfaces.
Moreover, no difference is noted according to the sex of the individual.
Side of the hormones also there is change. Doreen Kimura supports his
hormonal studies starting from taking away of saliva, to say as much that
sampling is doubtful. Thus blood taking away were carried out, and there still:
no significant result, the testosterone makes the math student. More generally
also, the human one seems to escape the hormonal laws because their fluctuations
leave our marble cortex.
It aims better than it
It has this innate direction of the throw of precision whereas the woman misses
once on two the dustbin which is with two meters of its office… Innate, really?
Is this finally there a sexually marked behavior which finds its origin in the
brain?
A prehistoric brain?
It aims very well and it is normal will say certain. A character inherited sound
very old ancestor prehistoric hunter, undoubtedly. A kind of atavism
Paleolithic? Can one explain the direction of the precision of the men by the
presence of a prehistoric function which Perdue but which finally does not have
any more raison d'être? A prehistoric cortex too adapted to the modern life.
If this assumption is followed, all becomes very clear, but also rather
false. The wandering hunters were to have a good direction of the orientation
for managing their territories well, keep silent themselves not to be made hear
their preys and aim well to be able to eat. A few millennia later one obtains a
man who has the direction of the orientation in spite of him, which speaks
finally rather little and which also is rather precise for him… Thus finally,
the differences in behavior between the men and the women of today are right the
remainders of the division of the tasks which took place in the past: the man
with hunting and the woman with the camping. Much too simple (and forgery) to be
true.
A plastic brain
How to affirm that our ancestors were distributed the tasks in this way? This
model is simply the model of the Western company of the XIXe century copied on a
world where this information escapes to us. Moreover, the ethnographic examples
do not fail to put at evil this assumption. There is a very great variability in
the allocation of the functions, according to companies'. Thus the argument of
the ancestral gene which perjure does not hold the road.
Moreover, we are born with an unfinished brain, the same one undoubtedly as
our old. But as we saw during various examples, we have the brain which we
build. Except pathologies and malformations, babies, we have all the same
cortex. It is well our life, our culture, our education, our experiments which
will carve it.
All the differences which make us cannot be inevitably explained by biology,
quite to the contrary. Our environment acts much more than one does not believe
on our brain.
Too not disappointed? You will not be able to say any more “I am only one
woman” in front of a plan or “I am only one man” in front of a woman on standby
of words. Oh yes we are different, but our brain does not testify any.
Attention with the dangerous drifts
The only observable sexual difference in our brain is our genetic sex. This last
is at the origin of a production of sex hormones which will impregnate our
cortex. But as we saw, it is not really sensitive to the hormonal fluctuations.
Nothing in our brain thus makes it possible to distinguish the man from the
woman and even less to justify the differences in behaviors observed. Then yes,
we create our own differences by the means of the life, our company, etc They
are certainly above all the sociocultural alternatives, but not biological. Let
us stop always seeking a biological cause with the differences. Indeed, this
step can only reinforce the tools for discrimination and science should not be
used for this stupid purpose. Even if the greatest scientific reviews
unceasingly relay information of this kind, “science spectacle” should not
especially make us forget that all the men are equal… and are born with the same
brain.
Cerebral operation is a complex ground. We have all the same structure and
yet we make use of it in a single way. If the sexual differences are
non-existent, the indivuelles variations are, they, very numerous. The brain is
as a modelling clay to which we give form each day.
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