Return to Video

Does the brain have a sex ? | Catherine Vidal | TEDxParis

  • 0:15 - 0:17
    Does the brain have a sex?
  • 0:17 - 0:23
    This is obviously a fundamental
    question that everyone asks.
  • 0:23 - 0:25
    So, according to initial popular belief:
  • 0:25 - 0:28
    Women have a brain smaller than men,
  • 0:28 - 0:31
    therefore, they would be
    less intelligent than men.
  • 0:31 - 0:34
    This idea stemmed from the 19th century,
  • 0:34 - 0:37
    during the heyday of craniometry
  • 0:37 - 0:42
    when doctors were interested to find
    links between the size of the skull,
  • 0:42 - 0:44
    the weight of the brain and intelligence.
  • 0:44 - 0:46
    It's important to note
    that for most of them
  • 0:46 - 0:51
    it was absolutely obvious and natural
    that men had a bigger brain than women,
  • 0:51 - 0:53
    whites bigger than blacks
  • 0:53 - 0:55
    and managers bigger than workers.
  • 0:55 - 0:57
    A big supporter of these theories,
  • 0:57 - 1:00
    is the French doctor Paul Broca
  • 1:00 - 1:03
    who measured a difference of 150 grams
  • 1:03 - 1:05
    between average weights
    of men's and women's brains,
  • 1:05 - 1:09
    men's weight was 1.350 kg
  • 1:09 - 1:10
    and women's 1.200 kg.
  • 1:10 - 1:14
    In 1861, Broca stated:
  • 1:14 - 1:19
    "We wondered if the smallness
    of a woman's brain did not solely depend
  • 1:19 - 1:22
    on the smallness of her body,
    nevertheless, one should not forget
  • 1:22 - 1:25
    that women on average
    are a little less intelligent than men."
  • 1:26 - 1:29
    So, anyway,
  • 1:29 - 1:32
    this question of link between
    the size of the brain and intelligence
  • 1:32 - 1:34
    is not asked anymore,
  • 1:34 - 1:37
    because the reality is, there is
    no relation between the two,
  • 1:37 - 1:40
    and we know it thanks
    to a certain number of male celebrities,
  • 1:40 - 1:43
    not women, who have given
    their brains to science.
  • 1:43 - 1:46
    A prominent person
    like Anatole France, for example,
  • 1:46 - 1:48
    had a brain that weighed one kilogram,
  • 1:48 - 1:51
    Tourgueniev had a brain that weighed 2 kg,
  • 1:51 - 1:54
    and as for Einstein,
    he had a small brain weighing 1.250 kg.
  • 1:54 - 1:57
    Meaning, of the same size as women's.
  • 1:57 - 2:01
    Another popular belief: women are skilled
    at doing more than one thing at a time
  • 2:01 - 2:04
    because the communications
    between their brain's hemispheres
  • 2:04 - 2:06
    are more developed as oppose to men's.
  • 2:06 - 2:11
    We know very well, they're multi-tasking.
    This idea comes from a study
  • 2:11 - 2:13
    published in 1982,
  • 2:13 - 2:16
    on 20 brains conserved in formalin
  • 2:16 - 2:18
    that showed that the corpus callosum,
  • 2:18 - 2:20
    that's the part surrounded by red,
  • 2:20 - 2:24
    the bundle of fibers that connects
    both cerebral hemispheres,
  • 2:24 - 2:27
    that corpus callosum was thicker
    for women than it was for men,
  • 2:27 - 2:29
    where perhaps better communication stems.
  • 2:29 - 2:34
    Now, since 1982, many things have gone by,
  • 2:34 - 2:36
    new technology developed,
  • 2:36 - 2:40
    in particular the new techniques
    of cerebral imagery such as MRI
  • 2:40 - 2:43
    which made it possible
    from then on to live the dream,
  • 2:43 - 2:48
    meaning to study a live brain
    no more studying a brain in formalin.
  • 2:48 - 2:50
    And if we gather the collection of studies
  • 2:50 - 2:53
    made on this corpus callosum
    since MRI was invented,
  • 2:53 - 2:56
    we realize that there is no difference
    between men and women
  • 2:56 - 2:58
    in the thickness of the corpus callosum.
  • 2:58 - 3:00
    Another popular belief:
  • 3:00 - 3:02
    "Women are more capable
    at learning languages
  • 3:02 - 3:05
    because they use both
    of their hemispheres to speak."
  • 3:05 - 3:07
    Let's see where this also comes from:
  • 3:07 - 3:11
    this comes from a study
    that was published in 1994,
  • 3:11 - 3:15
    a study using MRI during a language test,
  • 3:15 - 3:18
    and it showed that men, taking this test,
  • 3:18 - 3:21
    activated one hemisphere
    whereas women used both.
  • 3:21 - 3:25
    So, this study that was conducted
    on 19 men and women,
  • 3:25 - 3:29
    intrigued numerous researchers who
    looked into reproducing these results.
  • 3:29 - 3:33
    And if we were to gather now
    the collection of studies
  • 3:33 - 3:38
    that were published between 1995
    and 2009, including this one,
  • 3:38 - 3:41
    in total, 700 men and women were tested,
  • 3:41 - 3:43
    we find that statically speaking,
  • 3:43 - 3:46
    there is no difference
    between men and women
  • 3:46 - 3:49
    in the distribution of language areas.
  • 3:49 - 3:53
    And in fact, once a great number
    of subjects were analyzed,
  • 3:53 - 3:56
    the difference between the sexes,
    finally, disappeared.
  • 3:56 - 3:58
    We will see why.
  • 3:58 - 4:01
    Take this example, a study using MRI,
  • 4:01 - 4:04
    where we asked the subjects
    to do a mental calculation
  • 4:04 - 4:07
    that they were all successful at doing.
  • 4:07 - 4:10
    We could then see
    that in the women's group,
  • 4:10 - 4:13
    there was actually a great variability
  • 4:13 - 4:16
    in the distribution of areas in the brain
  • 4:16 - 4:18
    that were activated
    during this calculation.
  • 4:18 - 4:22
    This variability was equally
    found in the men's group.
  • 4:22 - 4:26
    Finally, to come to an even score
    for mental calculation,
  • 4:26 - 4:30
    each individual has their own way
    of activating their brain,
  • 4:30 - 4:34
    corresponding to many different strategies
  • 4:34 - 4:37
    to do mental calculations.
  • 4:37 - 4:41
    And, consequently,
    the variability that we can observe
  • 4:41 - 4:43
    between the individuals of the same sex,
  • 4:43 - 4:47
    equals or exceeds
    the variability between the sexes.
  • 4:48 - 4:50
    Another popular belief:
  • 4:50 - 4:53
    the differences of mental
    aptitudes between the sexes
  • 4:53 - 4:55
    originates from a biological origin.
  • 4:55 - 4:57
    There are indeed a certain number of tests
  • 4:57 - 5:00
    where women are known to perform better.
  • 5:00 - 5:04
    For example tests
    of visual perception of details,
  • 5:04 - 5:05
    such as this test here
  • 5:05 - 5:08
    where one must notice two identical houses
  • 5:08 - 5:12
    and the women are also better
    at tests of verbal fluency,
  • 5:12 - 5:14
    where a maximum number
    of words must be said
  • 5:14 - 5:16
    beginning with the same letter.
  • 5:16 - 5:18
    In short, all this is still
    not very complicated.
  • 5:18 - 5:23
    When it comes to men, they are better,
    or known to be better anyways,
  • 5:23 - 5:27
    at tests involving mental
    rotation of objects in 3D.
  • 5:28 - 5:31
    They are equally better
    at reaching a target.
  • 5:31 - 5:36
    So, based on the significance
    of these differences in performance,
  • 5:36 - 5:39
    we can ask the question:
    Are they inherent or are they acquired?
  • 5:39 - 5:43
    In fact, it must be noted
    that the differences in question
  • 5:43 - 5:46
    are detectable only in adolescence,
  • 5:46 - 5:49
    and that they disappear with learning.
  • 5:49 - 5:53
    Therefore, we can assume
    that education and culture
  • 5:53 - 5:56
    play an important role
    in the emergence of these differences.
  • 5:56 - 6:00
    There is also another important factor,
    which is the context
  • 6:00 - 6:03
    where these prominent tests are carried.
  • 6:03 - 6:08
    Let's take then this prominent test
    of mental rotation in 3D,
  • 6:08 - 6:12
    where one must say
    if the objects presented
  • 6:12 - 6:15
    are the same or if they are different.
  • 6:15 - 6:18
    If the test is given in a classroom
  • 6:18 - 6:22
    and the teacher says
    this is a geometry test,
  • 6:22 - 6:25
    at that moment,
    boys will be better than girls.
  • 6:25 - 6:30
    But if the teacher initially makes
    an announcement that this is an art test,
  • 6:30 - 6:33
    at that moment, boys and girls
    will have the same scores.
  • 6:33 - 6:36
    So, these results are interesting
  • 6:36 - 6:41
    which show how much self-esteem
    and gender stereotypes
  • 6:41 - 6:43
    affect the results of the tests.
  • 6:45 - 6:49
    Another example also is the difference
    in mathematical performances
  • 6:49 - 6:52
    between boys and girls,
    in the United States.
  • 6:52 - 6:57
    A large-scale statistical survey
    conducted on 10 million students
  • 6:57 - 7:00
    in 1990, showed, on average,
  • 7:00 - 7:03
    boys were a little better
    than girls at math tests,
  • 7:03 - 7:06
    and some have interpreted
    these results saying
  • 7:06 - 7:09
    that it was because girls did not have
    a brain made for math.
  • 7:09 - 7:13
    But the same survey
    that was commissioned in 2008,
  • 7:13 - 7:17
    shows equivalent scores
    for boys and girls.
  • 7:17 - 7:22
    So, for 20 years we had a disappearance
    of performance differences in math
  • 7:22 - 7:23
    between boys and girls,
  • 7:23 - 7:26
    which clearly shows
    that it's the education
  • 7:26 - 7:30
    and not the biology that explains
    these differences in scores.
  • 7:30 - 7:32
    Now, we will ask the question:
  • 7:32 - 7:35
    "How does education affect the brain?"
  • 7:36 - 7:40
    Our human brains are made up
    of 100 billion neurons
  • 7:40 - 7:42
    that are connected to each other
  • 7:42 - 7:47
    thanks to connections
    amounting to many billions.
  • 7:47 - 7:52
    Now 90% of these connections
    develop after birth.
  • 7:52 - 7:56
    And it's precisely on how these
    connections will come to be,
  • 7:56 - 7:59
    that these networks
    of neurons will develop,
  • 7:59 - 8:03
    and where education and culture
    will play an important part.
  • 8:03 - 8:06
    First example:
    brains of professional pianists,
  • 8:06 - 8:09
    also applicable for violinists,
    I assure you,
  • 8:09 - 8:12
    we can observe the MRI, for these people,
  • 8:12 - 8:15
    a thickness of the cerebral regions
  • 8:15 - 8:19
    which control the coordination
    of fingers as well as the hearing.
  • 8:19 - 8:21
    In fact, this phenomenon of thickness
  • 8:21 - 8:26
    is due to the connections produced
    between the extra neurons
  • 8:26 - 8:28
    and in addition it is proportional
  • 8:28 - 8:32
    to the time spent learning
    the piano since childhood.
  • 8:32 - 8:35
    And we use the term cerebral plasticity
  • 8:35 - 8:38
    to describe the brain's ability
  • 8:38 - 8:42
    at shaping up eventually
    to reflect experience.
  • 8:42 - 8:45
    Another example of cerebral
    plasticity in adulthood.
  • 8:45 - 8:48
    We take a group
    of twenty -year-old students
  • 8:48 - 8:51
    and we ask them to learn
    to juggle three balls.
  • 8:51 - 8:52
    And in just three months,
  • 8:52 - 8:55
    we find this phenomenon
    of the cortex thickening
  • 8:55 - 8:59
    in the regions that control
    the motor coordination and vision.
  • 8:59 - 9:02
    So, what's really interesting
    in this experiment is
  • 9:02 - 9:05
    that if the students
    stop practice juggling,
  • 9:05 - 9:09
    eventually the regions
    that thickened before will shrink.
  • 9:09 - 9:12
    And so, we strongly went ahead
    with this experiment
  • 9:12 - 9:15
    with people who are
    a little bit older, in their sixties,
  • 9:15 - 9:19
    and we find the same phenomenon
    of thickness as the young ones.
  • 9:19 - 9:20
    It is still rather reassuring,
  • 9:20 - 9:24
    it shows that cerebral plasticity
    persists with age.
  • 9:25 - 9:28
    Here we have an example
    extremely extraordinary
  • 9:28 - 9:30
    of cerebral plasticity.
  • 9:30 - 9:34
    A man who is 44 years old,
    married with two kids,
  • 9:34 - 9:37
    living a professional life
    completely normal,
  • 9:37 - 9:40
    who suffered from slight
    weakness in his leg.
  • 9:40 - 9:44
    We decided to do an MRI test
    and surprise surprise,
  • 9:44 - 9:49
    we discovered that his skull
    was essentially full of liquid
  • 9:49 - 9:52
    and his brain was reduced to a thin layer
  • 9:52 - 9:54
    flattened along
    the inner lining of the skull.
  • 9:54 - 9:56
    We then asked questions.
  • 9:56 - 10:00
    And, it turns out, this person
    suffered from hydrocephalus from birth,
  • 10:00 - 10:03
    so we placed a drain
    at the base of the skull
  • 10:03 - 10:08
    to discharge the excess liquid,
    but the drain was clogged
  • 10:08 - 10:11
    and finally the pressure
    of the liquid repressed the brain
  • 10:11 - 10:13
    along the inner lining of the skull.
  • 10:13 - 10:17
    And all this happened without causing
    any trouble in this patient's life
  • 10:17 - 10:19
    who never suspected anything.
  • 10:20 - 10:24
    So, now that you know
    everything on cerebral plasticity,
  • 10:24 - 10:27
    in terms of the brain's structure
    and function
  • 10:27 - 10:30
    which is modified in relation
    to history for each person,
  • 10:30 - 10:34
    you can now then understand
    why we all have very different brains,
  • 10:34 - 10:35
    regardless of sex.
  • 10:35 - 10:38
    However, what we do have in common
  • 10:38 - 10:41
    is this cerebral cortex
    gifted with plasticity
  • 10:41 - 10:44
    which has greatly developed
    in the course of evolution
  • 10:44 - 10:48
    and which had to crease in order
    to fit inside the cranium.
  • 10:49 - 10:52
    You have here in front of you,
    to the left, a real brain
  • 10:52 - 10:56
    and to the right, a model brain
    with the technological means,
  • 10:56 - 11:00
    we can have fun by unfolding it virtually.
  • 11:00 - 11:02
    And I will give you this experience.
  • 11:03 - 11:07
    Here I am unveiling the brain,
  • 11:07 - 11:08
    well, the skull, actually.
  • 11:09 - 11:11
    I am opening the cranium
  • 11:11 - 11:13
    and I am unfolding the cerebral cortex
  • 11:13 - 11:17
    which measures 2 m² on 3 mm of thickness,
  • 11:17 - 11:21
    and it's because of this cerebral cortex
    that all of us, men and women,
  • 11:21 - 11:24
    are able to reason, to think,
  • 11:24 - 11:27
    to dream and to imagine
    the future of humanity.
  • 11:27 - 11:28
    Thank you.
  • 11:28 - 11:31
    (Applause)
Title:
Does the brain have a sex ? | Catherine Vidal | TEDxParis
Description:

Catherine Vidal debunks popular beliefs and preconceived ideas regarding the brain based on the reality of facts.

more » « less
Video Language:
French
Team:
TED
Project:
TEDxTalks
Duration:
11:38
  • I'm sending these subtitles back for further improvement. Please correct the following issues:
    - total length of subtitles and lines
    - disjointed sections of sentences
    - reading speed

    In the new editor, you can see the character length of each subtitle, as well as its reading speed (characters/second). For languages based on the Latin alphabet, the maximum subtitle length is 84 characters (subtitles over 42 characters need to be broken into two lines). The maximum reading speed should not be over 21 characters per second. To learn more about line length, line breaking and reading speed, watch this tutorial: http://www.youtube.com/watch?v=yvNQoD32Qqo&list=PLuvL0OYxuPwxQbdq4W7TCQ7TBnW39cDRC

    Please split subtitles that are over 42 characters into two lines. Also, please fix the line breaks in most of the subtitles to make the lines more balanced in length and/or to keep linguistic "wholes" together (e.g. keep the word "that" in the same line as the clause that it introduces as a relative pronoun). To learn more about why and how to break subtitles into lines, see this guide on OTPedia: http://translations.ted.org/wiki/How_to_break_lines

    Please merge subtitles where they could work as a single two-line subtitle that forms a bigger part of a sentence and so, it's easier to translate into other languages than subtitles containing disjointed sections of the whole sentence. (English subtitles are often used as the source language in translation). To learn more, see http://translations.ted.org/wiki/English_Style_Guide#How_to_make_your_subtitles_a_good_source_for_translations

    Make sure the reading speed of the subtitles is not over 21 characters per second. In order to fix this, you can either compress the text (see http://translations.ted.org/wiki/How_to_Compress_Subtitles) or edit the timing of the subtitle. In many cases, you can merge subtitles to create a bigger subtitle with the correct reading speed. In order to merge subtitles, copy the text of the second subtitle, delete the second subtitle, paste its text into the first subtitle and extended its time to cover the duration of the deleted subtitle.

    If you have any questions don't hesitate to contact me.

    Thanks!

  • Hey there,

    Great job! Thank you for all the improvements you made. The translation is excellent. Reading speed and line breaks were applied correctly pretty much everywhere.

    All I did was to unbreak some subtitles that were no longer than 42 characters. It’s OK to occasionally break them if they consist of two little sentences, but in almost every case, you should not break subtitles that are no longer than 42 characters.

    I also fixed some line breaks in some subtitles to make the lines more balanced in length and/or to keep linguistic "wholes" together (e.g. keep the word "that" in the same line as the clause that it introduces as a relative pronoun). http://translations.ted.org/wiki/How_to_break_lines

    Best,
    Helene

English subtitles

Revisions Compare revisions