Annie Murphy Paul: What we learn before we're born

283,547 views ・ 2011-11-29

TED


Please double-click on the English subtitles below to play the video.

00:15
My subject today is learning.
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And in that spirit, I want to spring on you all a pop quiz.
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Ready?
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When does learning begin?
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Now as you ponder that question,
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maybe you're thinking about the first day of preschool
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or kindergarten,
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the first time that kids are in a classroom with a teacher.
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Or maybe you've called to mind the toddler phase
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when children are learning how to walk and talk
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and use a fork.
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Maybe you've encountered the Zero-to-Three movement,
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which asserts that the most important years for learning
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are the earliest ones.
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And so your answer to my question would be:
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Learning begins at birth.
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Well today I want to present to you
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an idea that may be surprising
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and may even seem implausible,
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but which is supported by the latest evidence
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from psychology and biology.
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And that is that some of the most important learning we ever do
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happens before we're born,
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while we're still in the womb.
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Now I'm a science reporter.
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I write books and magazine articles.
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01:21
And I'm also a mother.
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And those two roles came together for me
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in a book that I wrote called "Origins."
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"Origins" is a report from the front lines
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of an exciting new field
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called fetal origins.
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Fetal origins is a scientific discipline
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that emerged just about two decades ago,
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and it's based on the theory
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that our health and well-being throughout our lives
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is crucially affected
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by the nine months we spend in the womb.
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Now this theory was of more than just intellectual interest to me.
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I was myself pregnant
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while I was doing the research for the book.
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And one of the most fascinating insights
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I took from this work
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is that we're all learning about the world
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even before we enter it.
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When we hold our babies for the first time,
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we might imagine that they're clean slates,
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unmarked by life,
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when in fact, they've already been shaped by us
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and by the particular world we live in.
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Today I want to share with you some of the amazing things
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that scientists are discovering
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about what fetuses learn
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while they're still in their mothers' bellies.
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First of all,
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they learn the sound of their mothers' voices.
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Because sounds from the outside world
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have to travel through the mother's abdominal tissue
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and through the amniotic fluid that surrounds the fetus,
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the voices fetuses hear,
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starting around the fourth month of gestation,
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are muted and muffled.
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One researcher says
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that they probably sound a lot like the the voice of Charlie Brown's teacher
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in the old "Peanuts" cartoon.
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But the pregnant woman's own voice
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reverberates through her body,
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reaching the fetus much more readily.
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And because the fetus is with her all the time,
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it hears her voice a lot.
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Once the baby's born, it recognizes her voice
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and it prefers listening to her voice
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over anyone else's.
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How can we know this?
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Newborn babies can't do much,
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but one thing they're really good at is sucking.
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Researchers take advantage of this fact
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by rigging up two rubber nipples,
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so that if a baby sucks on one,
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it hears a recording of its mother's voice
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on a pair of headphones,
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and if it sucks on the other nipple,
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it hears a recording of a female stranger's voice.
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Babies quickly show their preference
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by choosing the first one.
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Scientists also take advantage of the fact
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that babies will slow down their sucking
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when something interests them
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and resume their fast sucking
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when they get bored.
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This is how researchers discovered
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that, after women repeatedly read aloud
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a section of Dr. Seuss' "The Cat in the Hat" while they were pregnant,
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their newborn babies recognized that passage
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when they hear it outside the womb.
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My favorite experiment of this kind
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is the one that showed that the babies
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of women who watched a certain soap opera
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every day during pregnancy
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recognized the theme song of that show
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once they were born.
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So fetuses are even learning
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about the particular language that's spoken
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in the world that they'll be born into.
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A study published last year
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found that from birth, from the moment of birth,
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babies cry in the accent
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of their mother's native language.
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French babies cry on a rising note
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while German babies end on a falling note,
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imitating the melodic contours
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of those languages.
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Now why would this kind of fetal learning
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be useful?
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It may have evolved to aid the baby's survival.
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From the moment of birth,
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the baby responds most to the voice
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of the person who is most likely to care for it --
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its mother.
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It even makes its cries
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sound like the mother's language,
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which may further endear the baby to the mother,
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and which may give the baby a head start
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in the critical task
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of learning how to understand and speak
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its native language.
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But it's not just sounds
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that fetuses are learning about in utero.
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It's also tastes and smells.
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By seven months of gestation,
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the fetus' taste buds are fully developed,
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and its olfactory receptors, which allow it to smell,
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are functioning.
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The flavors of the food a pregnant woman eats
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find their way into the amniotic fluid,
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which is continuously swallowed
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by the fetus.
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Babies seem to remember and prefer these tastes
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once they're out in the world.
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In one experiment, a group of pregnant women
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was asked to drink a lot of carrot juice
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during their third trimester of pregnancy,
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while another group of pregnant women
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drank only water.
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Six months later, the women's infants
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were offered cereal mixed with carrot juice,
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and their facial expressions were observed while they ate it.
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The offspring of the carrot juice drinking women
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ate more carrot-flavored cereal,
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and from the looks of it,
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they seemed to enjoy it more.
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A sort of French version of this experiment
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was carried out in Dijon, France
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where researchers found
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that mothers who consumed food and drink
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flavored with licorice-flavored anise during pregnancy
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showed a preference for anise
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on their first day of life,
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and again, when they were tested later,
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on their fourth day of life.
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Babies whose mothers did not eat anise during pregnancy
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showed a reaction that translated roughly as "yuck."
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What this means
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is that fetuses are effectively being taught by their mothers
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about what is safe and good to eat.
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Fetuses are also being taught
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about the particular culture that they'll be joining
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through one of culture's most powerful expressions,
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which is food.
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They're being introduced to the characteristic flavors and spices
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of their culture's cuisine
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even before birth.
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Now it turns out that fetuses are learning even bigger lessons.
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But before I get to that,
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I want to address something that you may be wondering about.
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The notion of fetal learning
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may conjure up for you attempts to enrich the fetus --
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like playing Mozart through headphones
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placed on a pregnant belly.
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But actually, the nine-month-long process
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of molding and shaping that goes on in the womb
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is a lot more visceral and consequential than that.
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Much of what a pregnant woman encounters in her daily life --
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the air she breathes,
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the food and drink she consumes,
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the chemicals she's exposed to,
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even the emotions she feels --
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are shared in some fashion with her fetus.
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They make up a mix of influences
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as individual and idiosyncratic
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as the woman herself.
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The fetus incorporates these offerings
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into its own body,
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makes them part of its flesh and blood.
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And often it does something more.
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It treats these maternal contributions
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as information,
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as what I like to call biological postcards
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from the world outside.
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So what a fetus is learning about in utero
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is not Mozart's "Magic Flute"
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but answers to questions much more critical to its survival.
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Will it be born into a world of abundance
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or scarcity?
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Will it be safe and protected,
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or will it face constant dangers and threats?
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Will it live a long, fruitful life
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or a short, harried one?
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The pregnant woman's diet and stress level in particular
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provide important clues to prevailing conditions
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like a finger lifted to the wind.
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The resulting tuning and tweaking
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of a fetus' brain and other organs
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are part of what give us humans
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our enormous flexibility,
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our ability to thrive
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in a huge variety of environments,
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from the country to the city,
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from the tundra to the desert.
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To conclude, I want to tell you two stories
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about how mothers teach their children about the world
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even before they're born.
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In the autumn of 1944,
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the darkest days of World War II,
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German troops blockaded Western Holland,
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turning away all shipments of food.
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The opening of the Nazi's siege
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was followed by one of the harshest winters in decades --
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so cold the water in the canals froze solid.
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Soon food became scarce,
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with many Dutch surviving on just 500 calories a day --
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a quarter of what they consumed before the war.
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As weeks of deprivation stretched into months,
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some resorted to eating tulip bulbs.
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By the beginning of May,
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the nation's carefully rationed food reserve
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was completely exhausted.
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The specter of mass starvation loomed.
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And then on May 5th, 1945,
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the siege came to a sudden end
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when Holland was liberated
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by the Allies.
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The "Hunger Winter," as it came to be known,
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killed some 10,000 people
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and weakened thousands more.
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But there was another population that was affected --
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the 40,000 fetuses
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in utero during the siege.
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Some of the effects of malnutrition during pregnancy
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were immediately apparent
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in higher rates of stillbirths,
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birth defects, low birth weights
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and infant mortality.
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But others wouldn't be discovered for many years.
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Decades after the "Hunger Winter,"
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researchers documented
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that people whose mothers were pregnant during the siege
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have more obesity, more diabetes
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and more heart disease in later life
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than individuals who were gestated under normal conditions.
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These individuals' prenatal experience of starvation
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seems to have changed their bodies
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in myriad ways.
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They have higher blood pressure,
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poorer cholesterol profiles
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and reduced glucose tolerance --
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a precursor of diabetes.
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Why would undernutrition in the womb
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result in disease later?
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One explanation
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is that fetuses are making the best of a bad situation.
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When food is scarce,
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they divert nutrients towards the really critical organ, the brain,
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and away from other organs
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like the heart and liver.
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This keeps the fetus alive in the short-term,
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but the bill comes due later on in life
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when those other organs, deprived early on,
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become more susceptible to disease.
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But that may not be all that's going on.
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It seems that fetuses are taking cues
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from the intrauterine environment
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and tailoring their physiology accordingly.
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They're preparing themselves
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for the kind of world they will encounter
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on the other side of the womb.
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The fetus adjusts its metabolism
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and other physiological processes
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in anticipation of the environment that awaits it.
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And the basis of the fetus' prediction
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is what its mother eats.
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The meals a pregnant woman consumes
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constitute a kind of story,
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a fairy tale of abundance
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or a grim chronicle of deprivation.
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This story imparts information
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that the fetus uses
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to organize its body and its systems --
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an adaptation to prevailing circumstances
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that facilitates its future survival.
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Faced with severely limited resources,
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a smaller-sized child with reduced energy requirements
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will, in fact, have a better chance
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of living to adulthood.
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The real trouble comes
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when pregnant women are, in a sense, unreliable narrators,
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when fetuses are led
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to expect a world of scarcity
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and are born instead into a world of plenty.
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This is what happened to the children of the Dutch "Hunger Winter."
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And their higher rates of obesity,
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diabetes and heart disease
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are the result.
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Bodies that were built to hang onto every calorie
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found themselves swimming in the superfluous calories
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of the post-war Western diet.
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The world they had learned about while in utero
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was not the same
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as the world into which they were born.
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Here's another story.
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At 8:46 a.m. on September 11th, 2001,
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there were tens of thousands of people
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in the vicinity of the World Trade Center
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in New York --
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commuters spilling off trains,
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waitresses setting tables for the morning rush,
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brokers already working the phones on Wall Street.
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1,700 of these people were pregnant women.
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When the planes struck and the towers collapsed,
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many of these women experienced the same horrors
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inflicted on other survivors of the disaster --
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the overwhelming chaos and confusion,
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the rolling clouds
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of potentially toxic dust and debris,
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the heart-pounding fear for their lives.
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About a year after 9/11,
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researchers examined a group of women
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who were pregnant
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when they were exposed to the World Trade Center attack.
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In the babies of those women
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who developed post-traumatic stress syndrome, or PTSD,
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following their ordeal,
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researchers discovered a biological marker
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of susceptibility to PTSD --
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an effect that was most pronounced
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in infants whose mothers experienced the catastrophe
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in their third trimester.
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In other words,
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the mothers with post-traumatic stress syndrome
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had passed on a vulnerability to the condition
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to their children while they were still in utero.
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Now consider this:
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post-traumatic stress syndrome
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appears to be a reaction to stress gone very wrong,
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causing its victims tremendous unnecessary suffering.
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But there's another way of thinking about PTSD.
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What looks like pathology to us
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may actually be a useful adaptation
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in some circumstances.
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In a particularly dangerous environment,
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the characteristic manifestations of PTSD --
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a hyper-awareness of one's surroundings,
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a quick-trigger response to danger --
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could save someone's life.
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The notion that the prenatal transmission of PTSD risk is adaptive
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is still speculative,
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but I find it rather poignant.
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It would mean that, even before birth,
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mothers are warning their children
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that it's a wild world out there,
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telling them, "Be careful."
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Let me be clear.
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Fetal origins research is not about blaming women
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for what happens during pregnancy.
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It's about discovering how best to promote
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the health and well-being of the next generation.
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That important effort must include a focus
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on what fetuses learn
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during the nine months they spend in the womb.
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Learning is one of life's most essential activities,
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and it begins much earlier
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than we ever imagined.
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Thank you.
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(Applause)
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About this website

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