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  • So what does it mean to be a woman?

  • We all have XX chromosomes, right?

  • Actually, that's not true.

  • Some women are mosaics.

  • They have a mix of chromosome types with X, with XY or with XXX.

  • If it's not just about our chromosomes,

  • then what is being a woman about?

  • Being feminine?

  • Getting married?

  • Having kids?

  • You don't have to look far to find fantastic exceptions

  • to these rules,

  • but we all share something that makes us women.

  • Maybe that something is in our brains.

  • You might have heard theories from last century

  • about how men are better at math than women

  • because they have bigger brains.

  • These theories have been debunked.

  • The average man has a brain about three times smaller

  • than the average elephant,

  • but that doesn't mean

  • the average man is three times dumber than an elephant ...

  • or does it?

  • (Laughter)

  • There's a new wave of female neuroscientists

  • that are finding important differences between female and male brains

  • in neuron connectivity,

  • in brain structure, in brain activity.

  • They're finding that the brain is like a patchwork mosaic --

  • a mixture.

  • Women have mostly female patches and a few male patches.

  • With all this new data, what does it mean to be a woman?

  • This is something that I've been thinking about almost my entire life.

  • When people learn that I'm a woman who happens to be transgender,

  • they always ask,

  • "How do you know you're a woman?"

  • As a scientist, I'm searching for a biological basis of gender.

  • I want to understand what makes me me.

  • New discoveries at the front edge of science

  • are shedding light on the biomarkers that define gender.

  • My colleagues and I in genetics, neuroscience, physiology and psychology,

  • we're trying to figure out exactly how gender works.

  • These vastly different fields share a common connection --

  • epigenetics.

  • In epigenetics, we're studying how DNA activity

  • can actually radically and permanently change,

  • even though the sequence stays the same.

  • DNA is the long, string-like molecule that winds up inside our cells.

  • There's so much DNA

  • that it actually gets tangled into these knot-like things --

  • we'll just call them knots.

  • So external factors change how those DNA knots are formed.

  • You can think of it like this:

  • inside our cells, there's different contraptions building things,

  • connecting circuits,

  • doing all the things they need to make life happen.

  • Here's one that's sort of reading the DNA and making RNA.

  • And then this one is carrying a huge sac of neurotransmitters

  • from one end of the brain cell

  • to the other.

  • Don't they get hazard pay for this kind of work?

  • (Laughter)

  • This one is an entire molecular factory --

  • some say it's the secret to life.

  • It's call the ribosome.

  • I've been studying this since 2001.

  • One of the stunning things about our cells

  • is that the components inside them are actually biodegradable.

  • They dissolve,

  • and then they're rebuilt each day,

  • kind of like a traveling carnival

  • where the rides are taken down and then rebuilt every single day.

  • A big difference between our cells and the traveling carnival

  • is that in the carnival,

  • there are skilled craftsmen that rebuild the rides each day.

  • In our cells, there are no such skilled craftsmen,

  • only dumb builder machines

  • that build whatever's written in the plans,

  • no matter what those plans say.

  • Those plans are the DNA.

  • The instructions for every nook and cranny inside our cells.

  • If everything in, say, our brain cells

  • dissolves almost every day,

  • then how can the brain remember anything past one day?

  • That's where DNA comes in.

  • DNA is one of the those things that does not dissolve.

  • But for DNA to remember that something happened,

  • it has to change somehow.

  • We know the change can't be in the sequence;

  • if it changed sequence all the time,

  • then we might be growing like, a new ear or a new eyeball every single day.

  • (Laughter)

  • So, instead it changes shape,

  • and that's where those DNA knots come in.

  • You can think of them like DNA memory.

  • When something big in our life happens,

  • like a traumatic childhood event,

  • stress hormones flood our brain.

  • The stress hormones don't affect the sequence of DNA,

  • but they do change the shape.

  • They affect that part of DNA

  • with the instructions for molecular machines that reduce stress.

  • That piece of DNA gets wound up into a knot,

  • and now the dumb builder machines can't read the plans they need

  • to build the machines that reduce stress.

  • That's a mouthful, but it's what's happening on the microscale.

  • On the macroscale, you practically lose the ability to deal with stress,

  • and that's bad.

  • And that's how DNA can remember what happens in the past.

  • This is what I think was happening to me

  • when I first started my gender transition.

  • I knew I was a woman on the inside,

  • and I wore women's clothes on the outside,

  • but everyone saw me as a man in a dress.

  • I felt like no matter how many things I try,

  • no one would ever really see me as a woman.

  • In science, your credibility is everything,

  • and people were snickering in the hallways,

  • giving me stares,

  • looks of disgust --

  • afraid to be near me.

  • I remember my first big talk after transition.

  • It was in Italy.

  • I'd given prestigious talks before,

  • but this one, I was terrified.

  • I looked out into the audience,

  • and the whispers started --

  • the stares,

  • the smirks, the chuckles.

  • To this day, I still have social anxiety around my experience eight years ago.

  • I lost hope.

  • Don't worry, I've had therapy so I'm OK --

  • I'm OK now.

  • (Laughter)

  • (Cheers)

  • (Applause)

  • But I felt enough is enough:

  • I'm a scientist,

  • I have a doctorate in astrophysics,

  • I've published in the top journals,

  • in wave-particle interactions, space physics,

  • nucleic acid biochemistry.

  • I've actually been trained to get to the bottom of things, so --

  • (Laughter)

  • I went online --

  • (Applause)

  • So I went online, and I found fascinating research papers.

  • I learned that these DNA knot things are not always bad.

  • Actually, the knotting and unknotting --

  • it's like a complicated computer language.

  • It programs our bodies with exquisite precision.

  • So when we get pregnant,

  • our fertilized eggs grow into newborn babies.

  • This process requires thousands of DNA decisions to happen.

  • Should an embryo cell become a blood cell?

  • A heart cell? A brain cell?

  • And the decisions happen at different times during pregnancy.

  • Some in the first trimester, some in the second trimester

  • and some in the third trimester.

  • To truly understand DNA decision-making,

  • we need to see the process of knot formation in atomic detail.

  • Even the most powerful microscopes can't see this.

  • What if we tried to simulate these on a computer?

  • For that we'd need a million computers to do that.

  • That's exactly what we have at Los Alamos Labs --

  • a million computers connected in a giant warehouse.

  • So here we're showing the DNA making up an entire gene

  • folded into very specific shapes of knots.

  • For the first time,

  • my team has simulated an entire gene of DNA --

  • the largest biomolecular simulation performed to date.

  • For the first time, we're beginning to understand the unsolved problem

  • of how hormones trigger the formation of these knots.

  • DNA knot formation can be seen beautifully in calico cats.

  • The decision between orange and black

  • happens early on in the womb,

  • so that orange-and-black patchy pattern,

  • it's an exact readout of what happened

  • when that cat was just a tiny little kitten embryo

  • inside her mom's womb.

  • And the patchy pattern actually happens in our brains and in cancer.

  • It's directly related to intellectual disability and breast cancer.

  • These DNA decisions also happen in other parts of the body.

  • It turns out that the precursor genitals transform into either female or male

  • during the first trimester of pregnancy.

  • The precursor brains, on the other hand,

  • transform into female or male during the second trimester of pregnancy.

  • So the current working model

  • is that a unique mix in my mom's womb

  • caused the precursor genitals to transform one way,

  • but the precursor brain to transform the other way.

  • Most of epigenetic research

  • has really focused on stress, anxiety, depression --

  • kind of a downer,

  • kind of bad things.

  • (Laughter)

  • But nowadays --

  • the latest stuff --

  • people are looking at relaxation.

  • Can that have a positive effect on your DNA?

  • Right now we're missing key data from mice models.

  • We know that mice relax,

  • but could they meditate like the Dalai Lama?

  • Achieve enlightenment?

  • Could they move stones with their mind like Jedi Master Yoda?

  • (Yoda voice): Hm, a Jedi mouse must feel the force flow, hm.

  • (Laughter)

  • (Applause)

  • I wonder if the support I've had since that talk back in Italy

  • has tried to unwind my DNA.

  • Having a great circle of friends, supportive parents

  • and being in a loving relationship

  • has actually given me strength and hope to help others.

  • At work I wear a rainbow bracelet.

  • Sometimes it raises eyebrows, but it also raises awareness.

  • There's so many transgender people --

  • especially women of color --

  • that are just one demeaning comment away from taking their own lives.

  • Forty percent of us attempt suicide.

  • If you're listening and you feel like you have no other option,

  • try to call a friend,

  • go online or try to get in a support group.

  • If you're a woman who's not transgender but you know pain of isolation,

  • of sexual assault --

  • reach out.

  • So what does it mean to be a woman?

  • The latest research is showing

  • that female and male brains do develop differently in the womb,

  • possibly giving us females this innate sense of being a woman.

  • On the other hand,

  • maybe it's our shared sense of commonality that makes us women.

  • We come in so many different shapes and sizes

  • that asking what it means to be a woman may not be the right question.

  • It's like asking a calico cat what it means to be a calico cat.

  • Maybe becoming a woman means accepting ourselves

  • for who we really are

  • and acknowledging the same in each other.

  • I see you.

  • And you've just seen me.

  • (Applause and cheers)

So what does it mean to be a woman?

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B2 US TED dna woman brain precursor female

【TED】Karissa Sanbonmatsu: The biology of gender, from DNA to the brain (The biology of gender, from DNA to the brain | Karissa Sanbonmatsu)

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    林宜悉 posted on 2019/02/11
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