字幕表 動画を再生する 英語字幕をプリント My subject today is learning.And in that spirit, I want to spring on you all a pop quiz.Ready?When does learning begin?Now as you ponder that question,maybe you're thinking about the first day of preschoolor kindergarten,the first time that kids are in a classroom with a teacher.Or maybe you've called to mind the toddler phasewhen children are learning how to walk and talkand use a fork.Maybe you've encountered the Zero-to-Three movement,which asserts that the most important years for learningare the earliest ones.And so your answer to my question would be:Learning begins at birth. Well today I want to present to youan idea that may be surprisingand may even seem implausible,but which is supported by the latest evidencefrom psychology and biology.And that is that some of the most important learning we ever dohappens before we're born,while we're still in the womb.Now I'm a science reporter.I write books and magazine articles.And I'm also a mother.And those two roles came together for mein a book that I wrote called "Origins.""Origins" is a report from the front linesof an exciting new fieldcalled fetal origins.Fetal origins is a scientific disciplinethat emerged just about two decades ago,and it's based on the theorythat our health and well-being throughout our livesis crucially affectedby the nine months we spend in the womb.Now this theory was of more than just intellectual interest to me.I was myself pregnantwhile I was doing the research for the book.And one of the most fascinating insightsI took from this workis that we're all learning about the worldeven before we enter it. When we hold our babies for the first time,we might imagine that they're clean slates,unmarked by life,when in fact, they've already been shaped by usand by the particular world we live in.Today I want to share with you some of the amazing thingsthat scientists are discoveringabout what fetuses learnwhile they're still in their mothers' bellies. First of all,they learn the sound of their mothers' voices.Because sounds from the outside worldhave to travel through the mother's abdominal tissueand through the amniotic fluid that surrounds the fetus,the voices fetuses hear,starting around the fourth month of gestation,are muted and muffled.One researcher saysthat they probably sound a lot like the the voice of Charlie Brown's teacherin the old "Peanuts" cartoon.But the pregnant woman's own voicereverberates through her body,reaching the fetus much more readily.And because the fetus is with her all the time,it hears her voice a lot.Once the baby's born, it recognizes her voiceand it prefers listening to her voiceover anyone else's. How can we know this?Newborn babies can't do much,but one thing they're really good at is sucking.Researchers take advantage of this factby rigging up two rubber nipples,so that if a baby sucks on one,it hears a recording of its mother's voiceon a pair of headphones,and if it sucks on the other nipple,it hears a recording of a female stranger's voice.Babies quickly show their preferenceby choosing the first one.Scientists also take advantage of the factthat babies will slow down their suckingwhen something interests themand resume their fast suckingwhen they get bored.This is how researchers discoveredthat, after women repeatedly read alouda section of Dr. Seuss' "The Cat in the Hat" while they were pregnant,their newborn babies recognized that passagewhen they hear it outside the womb.My favorite experiment of this kindis the one that showed that the babiesof women who watched a certain soap operaevery day during pregnancyrecognized the theme song of that showonce they were born.So fetuses are even learningabout the particular language that's spokenin the world that they'll be born into. A study published last yearfound that from birth, from the moment of birth,babies cry in the accentof their mother's native language.French babies cry on a rising notewhile German babies end on a falling note,imitating the melodic contoursof those languages.Now why would this kind of fetal learningbe useful?It may have evolved to aid the baby's survival.From the moment of birth,the baby responds most to the voiceof the person who is most likely to care for it --its mother.It even makes its criessound like the mother's language,which may further endear the baby to the mother,and which may give the baby a head startin the critical taskof learning how to understand and speakits native language. But it's not just soundsthat fetuses are learning about in utero.It's also tastes and smells.By seven months of gestation,the fetus' taste buds are fully developed,and its olfactory receptors, which allow it to smell,are functioning.The flavors of the food a pregnant woman eatsfind their way into the amniotic fluid,which is continuously swallowedby the fetus.Babies seem to remember and prefer these tastesonce they're out in the world.In one experiment, a group of pregnant womenwas asked to drink a lot of carrot juiceduring their third trimester of pregnancy,while another group of pregnant womendrank only water.Six months later, the women's infantswere offered cereal mixed with carrot juice,and their facial expressions were observed while they ate it.The offspring of the carrot juice drinking womenate more carrot-flavored cereal,and from the looks of it,they seemed to enjoy it more. A sort of French version of this experimentwas carried out in Dijon, Francewhere researchers foundthat mothers who consumed food and drinkflavored with licorice-flavored anise during pregnancyshowed a preference for aniseon their first day of life,and again, when they were tested later,on their fourth day of life.Babies whose mothers did not eat anise during pregnancyshowed a reaction that translated roughly as "yuck."What this meansis that fetuses are effectively being taught by their mothersabout what is safe and good to eat.Fetuses are also being taughtabout the particular culture that they'll be joiningthrough one of culture's most powerful expressions,which is food.They're being introduced to the characteristic flavors and spicesof their culture's cuisineeven before birth. Now it turns out that fetuses are learning even bigger lessons.But before I get to that,I want to address something that you may be wondering about.The notion of fetal learningmay conjure up for you attempts to enrich the fetus --like playing Mozart through headphonesplaced on a pregnant belly.But actually, the nine-month-long processof molding and shaping that goes on in the wombis a lot more visceral and consequential than that.Much of what a pregnant woman encounters in her daily life --the air she breathes,the food and drink she consumes,the chemicals she's exposed to,even the emotions she feels --are shared in some fashion with her fetus.They make up a mix of influencesas individual and idiosyncraticas the woman herself.The fetus incorporates these offeringsinto its own body,makes them part of its flesh and blood.And often it does something more.It treats these maternal contributionsas information,as what I like to call biological postcardsfrom the world outside. So what a fetus is learning about in uterois not Mozart's "Magic Flute"but answers to questions much more critical to its survival.Will it be born into a world of abundanceor scarcity?Will it be safe and protected,or will it face constant dangers and threats?Will it live a long, fruitful lifeor a short, harried one?The pregnant woman's diet and stress level in particularprovide important clues to prevailing conditionslike a finger lifted to the wind.The resulting tuning and tweakingof a fetus' brain and other organsare part of what give us humansour enormous flexibility,our ability to thrivein a huge variety of environments,from the country to the city,from the tundra to the desert. To conclude, I want to tell you two storiesabout how mothers teach their children about the worldeven before they're born.In the autumn of 1944,the darkest days of World War II,German troops blockaded Western Holland,turning away all shipments of food.The opening of the Nazi's siegewas followed by one of the harshest winters in decades --so cold the water in the canals froze solid.Soon food became scarce,with many Dutch surviving on just 500 calories a day --a quarter of what they consumed before the war.As weeks of deprivation stretched into months,some resorted to eating tulip bulbs.By the beginning of May,the nation's carefully rationed food reservewas completely exhausted.The specter of mass starvation loomed.And then on May 5th, 1945,the siege came to a sudden endwhen Holland was liberatedby the Allies. The "Hunger Winter," as it came to be known,killed some 10,000 peopleand weakened thousands more.But there was another population that was affected --the 40,000 fetusesin utero during the siege.Some of the effects of malnutrition during pregnancywere immediately apparentin higher rates of stillbirths,birth defects, low birth weightsand infant mortality.But others wouldn't be discovered for many years.Decades after the "Hunger Winter,"researchers documentedthat people whose mothers were pregnant during the siegehave more obesity, more diabetesand more heart disease in later lifethan individuals who were gestated under normal conditions.These individuals' prenatal experience of starvationseems to have changed their bodiesin myriad ways.They have higher blood pressure,poorer cholesterol profilesand reduced glucose tolerance --a precursor of diabetes. Why would undernutrition in the wombresult in disease later?One explanationis that fetuses are making the best of a bad situation.When food is scarce,they divert nutrients towards the really critical organ, the brain,and away from other organslike the heart and liver.This keeps the fetus alive in the short-term,but the bill comes due later on in lifewhen those other organs, deprived early on,become more susceptible to disease. But that may not be all that's going on.It seems that fetuses are taking cuesfrom the interuterine environmentand tailoring their physiology accordingly.They're preparing themselvesfor the kind of world they will encounteron the other side of the womb.The fetus adjusts its metabolismand other physiological processesin anticipation of the environment that awaits it.And the basis of the fetus' predictionis what its mother eats.The meals a pregnant woman consumesconstitute a kind of story,a fairy tale of abundanceor a grim chronicle of deprivation.This story imparts informationthat the fetus usesto organize its body and its systems --an adaptation to prevailing circumstancesthat facilitates its future survival.Faced with severely limited resources,a smaller-sized child with reduced energy requirementswill, in fact, have a better chanceof living to adulthood. The real trouble comeswhen pregnant women are, in a sense, unreliable narrators,when fetuses are ledto expect a world of scarcityand are born instead into a world of plenty.This is what happened to the children of the Dutch "Hunger Winter."And their higher rates of obesity,diabetes and heart diseaseare the result.Bodies that were built to hang onto every caloriefound themselves swimming in the superfluous caloriesof the post-war Western diet.The world they had learned about while in uterowas not the sameas the world into which they were born. Here's another story.At 8:46 a.m. on September 11th, 2001,there were tens of thousands of peoplein the vicinity of the World Trade Centerin New York --commuters spilling off trains,waitresses setting tables for the morning rush,brokers already working the phones on Wall Street.1,700 of these people were pregnant women.When the planes struck and the towers collapsed,many of these women experienced the same horrorsinflicted on other survivors of the disaster --the overwhelming chaos and confusion,the rolling cloudsof potentially toxic dust and debris,the heart-pounding fear for their lives. About a year after 9/11,researchers examined a group of womenwho were pregnantwhen they were exposed to the World Trade Center attack.In the babies of those womenwho developed post-traumatic stress syndrome, or PTSD,following their ordeal,researchers discovered a biological markerof susceptibility to PTSD --an effect that was most pronouncedin infants whose mothers experienced the catastrophein their third trimester.In other words,the mothers with post-traumatic stress syndromehad passed on a vulnerability to the conditionto their children while they were still in utero. Now consider this:post-traumatic stress syndromeappears to be a reaction to stress gone very wrong,causing its victims tremendous unnecessary suffering.But there's another way of thinking about PTSD.What looks like pathology to usmay actually be a useful adaptationin some circumstances.In a particularly dangerous environment,the characteristic manifestations of PTSD --a hyper-awareness of one's surroundings,a quick-trigger response to danger --could save someone's life.The notion that the prenatal transmission of PTSD risk is adaptiveis still speculative,but I find it rather poignant.It would mean that, even before birth,mothers are warning their childrenthat it's a wild world out there,telling them, "Be careful." Let me be clear.Fetal origins research is not about blaming womenfor what happens during pregnancy.It's about discovering how best to promotethe health and well-being of the next generation.That important effort must include a focuson what fetuses learnduring the nine months they spend in the womb.Learning is one of life's most essential activities,and it begins much earlierthan we ever imagined. Thank you. (Applause)
B2 中上級 Ted.comトーク - 赤ちゃんが生まれる前に学ぶこと (Ted.com talk - What babies learn before they're born) 507 45 Halu Hsieh に公開 2021 年 01 月 14 日 シェア シェア 保存 報告 動画の中の単語