NOVA scienceNOW: July 21, 2009

PBS Airdate: July 21, 2009
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NEIL DeGRASSE TYSON (Astrophysicist/American Museum of Natural History): On this episode of NOVA scienceNOW you'll meet some walruses with impressive brawn and brains...

ZIYA TONG (Correspondent): Sit up.

Oh, get out of town!

NEIL DeGRASSE TYSON: ...and a sea lion who takes her schoolwork very seriously.

COLLEEN REICHMUTH (University of California, Santa Cruz, Long Marine Laboratory): Sea lions can pass tests that are very difficult for many other species to pass, including humans.

NEIL DeGRASSE TYSON: So are these just fancy circus tricks?

SIVUQAQ (A Walrus): Ohhhhhhhh.

NEIL DeGRASSE TYSON: Or does this gift for gab...

LEAH COOMBS (Six Flags Discovery Kingdom): Knock.

NEIL DeGRASSE TYSON: ...and ability to reason demonstrate that animals are smarter than we think?

And did you ever wonder what makes some people picky eaters? According to my mother, I was never one of them.

SUNCHITA F. TYSON (Neil deGrasse Tyson's Mother): He ate everything that was put in front of him.

NEIL DeGRASSE TYSON: And I still do. But was it because my mother was strict?

SUNCHITA TYSON: There was no question about being picky. I didn't even know what the word meant.

NEIL DeGRASSE TYSON: Or could it be food tastes better to me because it's in my genes?

DENNIS DRAYNA: We, ultimately, were able to pinpoint the actual gene that causes this.

NEIL DeGRASSE TYSON: And, in our profile, you'll meet a doctor whose taste for science began when she performed surgery on the family answering machine.

SANGEETA BHATIA (Harvard - MIT): I took it apart and laid all the pieces on the table and fixed it. There were some parts left over but it was working anyway, so I called it a day.

NEIL DeGRASSE TYSON: Today, she's trying to revolutionize transplant surgery, and she's already had a major breakthrough in the race to build the first ever artificial liver.

SANGEETA BHATIA: The moment that I looked into the microscope and saw that this had actually come to fruition was amazing.

NEIL DeGRASSE TYSON: All that and more on this episode of NOVA scienceNow.

Funding for NOVA scienceNOW is provided by the National Science Foundation, where discoveries begin. And...

Discover new knowledge; biomedical research and science education; Howard Hughes Medical Institute: HHMI.

And the Alfred P. Sloan Foundation, to enhance public understanding of science and technology and to portray the lives of men and women engaged in scientific and technological pursuit.

And the George D. Smith Fund.

And by PBS viewers like you. Thank you.


NEIL DeGRASSE TYSON: Hello, I'm Neil deGrasse Tyson, your host for NOVA scienceNOW.

Can you imagine sitting down for a meal and getting served something that you know will taste so bitter, so vile, but it's really good for you and you have no choice but to eat it?

Thank you.

For some people out there this is just what it's like to eat foods that most others find delicious. Why do people have such different reactions to the same thing? Well, as I found out, the answer may just lie in their genes.


Some kids love to eat, they'll eat almost anything. But others just hate the foods that are best for them.

BOY: I don't like that green stuff. I don't want it.

NEIL DeGRASSE TYSON: Some kids are picky eaters.

NEIL DeGRASSE TYSON: According to my mom, I was never one of them.

SUNCHITA TYSON: Ever since he was a little toddler, he ate everything that was put in front of him.

NEIL DeGRASSE TYSON: And it's a good thing I did.

SUNCHITA TYSON: There was no question about being picky. I didn't even know what the word meant.

NEIL DeGRASSE TYSON: So why are some people picky and others not?

DANIELLE R. REED (Monell Chemical Senses Center): Just like we all differ in our ability to see and to hear, people differ in their ability to taste.

NEIL DeGRASSE TYSON: What makes a dish taste good to some people and terrible to others? I was determined to find out, and I couldn't think of a better way to do it than to invite biologists Bob Margolskee and Stuart Firestein for a tasty meal.

I love good food, although it's still a mystery to me how my sense of taste works. So, to set me straight, the chef and my colleagues came up with a little experiment. Much to my surprise, it involved a lot more than my tongue.

Hey, wait, my food is coming. What, what are you doing?

STUART FIRESTEIN (Columbia University): I'm over here now, Neil. I'm over here now. Ready for this experiment?

NEIL DeGRASSE TYSON: I'm ready to eat.

STUART FIRESTEIN: All right, open wide, here it comes. I want you to describe now, just what you're sensing in your mouth.

NEIL DeGRASSE TYSON: I don't taste anything.

STUART FIRESTEIN: That's because flavor really consists of several different sensory modalities. It's not just the taste in your mouth...


STUART FIRESTEIN: ...but also the way the food smells in your nose, the way it looks on the plate, the way it feels in your mouth.


STUART FIRESTEIN: I'm going to take your nose plug off, and I want you to breathe out while I do that. Okay, breathe out.

NEIL DeGRASSE TYSON: Wow, completely different. Oh, it's fruit.

I get some sort of sweet spices, like, I get a little bit of cinnamon, maybe a little bit of clove.

STUART FIRESTEIN: So now let's take a look at what you've been eating.


So why couldn't I taste it without my nose? Why should my nose have anything to do with it at all?

STUART FIRESTEIN: Well I think evolution has seen fit to devote as much of our sensory apparatus as possible to what we eat. You are, after all, what you eat.

NEIL DeGRASSE TYSON: And so were our caveman ancestors. They had to use all their senses to find the nutrients they needed to survive in a hostile environment. And just like us, they probably loved sweets. And there's an evolutionary reason for that: the sugar in sweet foods provides a lot of energy.

ROBERT F. MARGOLSKEE (Monell Chemical Senses Center): Sweet is very important and most people strongly prefer sweet. This is a direct measure of the nutritive value of a food.

NEIL DeGRASSE TYSON: On the other hand we have a very different relationship with that bitter taste in many vegetables. Bitter is a warning.

BOB MARGOLSKEE: Bitter is a protective sense. It's a signal for something potentially poisonous. A plant puts out a toxic compound so people won't eat it.

NEIL DeGRASSE TYSON: So the bitter flavor in a plant prevents people from eating it. Our bitter taste buds honor and respect that fact in a plant?


STUART FIRESTEIN: Finally, you got it. Geez.

NEIL DeGRASSE TYSON: I got it, but my colleagues still hadn't explained why people like me love eating broccoli while others think it's got a nasty, bitter flavor.

Stuart and Bob assured me the answer to this taste bud mystery was on the tip of my tongue.

These are taste buds, and those long slender leaf-like shapes are taste cells. These cells enable us to detect five basic flavors: sweet, salty, bitter, sour and umami, the Japanese word for the savory taste in meat and cheese.

On the outside of each taste cell are finger-like projections, covered with hundreds of tiny taste receptors. And when those receptors bind with the foods we eat, it opens a chemical pathway into the cell that leads all the way up to the brain; that's what we call taste.

So, why do some people hate that bitter taste found in green plants like broccoli and Brussels sprouts and others, like me, enjoy it? It's all because of those little taste receptors on your tongue, they're actually proteins, made by your genes.

You've heard of genes: they're subunits of our D.N.A., that long chain of four chemicals, best known by their initials, A, C, G and T.

Biologists have discovered that, out of the thousands of genes in our D.N.A., there's one that determines if we like the taste of some healthy greens or if we can't stand them.

And that single gene was discovered by geneticist Dennis Drayna. He found it by testing how strongly people react to the taste of P.T.C., a compound a lot like the chemical found naturally in vegetables like cauliflower and broccoli. While some people hate the taste of P.T.C, others can't taste it at all.

Dennis found the reason why, and it's in our genes.

DENNIS DRAYNA: Lo and behold, what did we find? We ultimately were able to pinpoint the actual gene that causes this.

Ah ha!

NEIL DeGRASSE TYSON: A gene that determines how we perceive that bitter flavor in broccoli that so many people hate.

So I have this perfectly prepared salmon on this sauce of broccoli. As I chowed down on a plate of healthy greens, I wanted to know just how this gene works, and why it turns some of us into broccoli eaters and others into picky eaters.

Geneticist Danielle Reed and bio-psychologist Julie Menella are finding answers to this question with the help of middle school students like these.

DANIELLE REED: The experiment we're going to do today is actually quite fun.

One, two, three.

NEIL DeGRASSE TYSON: Students rub their cheeks with a sterile swab, giving researchers easy access to a sample of their D.N.A.

Those four letters in D.N.A., they're packed into 23 pairs of chromosomes. On one of those pairs is the gene they're looking for.

DANIELLE REED: You get one chromosome from your mom and one chromosome from you dad. So this chromosome might have a gene that's a non-taster gene, and this chromosome from your dad might also be a non-taster gene.

NEIL DeGRASSE TYSON: Non-tasters don't taste the bitterness in many vegetables because they have the letters G-T-A in that order in a certain spot on the gene. When you get G-T-A from your mom and dad, those taste receptors on your tongue can't bind with the bitterness in broccoli. But instead, if you get the letters C-C-G from both your mom and dad, you can taste the bitterness in broccoli, and you're a "taster."

DANIELLE REED: And that makes you very sensitive to bitter.

YOUNG VOICE: Oh, yuck!

NEIL DeGRASSE TYSON: Now, I bet you're wondering what would happen if you got one of each.

DANIELLE REED: You might think of that as being a "medium bitter-taster."

NEIL DeGRASSE TYSON: Over time, it may be possible for medium bitter-tasters to actually learn to like the bitterness in broccoli.

Back in the lab, Danielle analyzes the kids' swabs. She thinks she can predict who hates the bitterness of broccoli, based solely on their D.N.A.

She then returns to the classroom to share the results with students and their parents.

But first, they give each kid some P.T.C. to drink.

As she expects, some taste absolutely nothing, while others wished they'd stayed home, especially Reed and Jarrod. When they see their D.N.A. results, it comes as no surprise; they've both got the form of this gene which makes them very sensitive to bitter. And guess what? Neither of them likes broccoli.

GAIL MOMJIAN (Reed's Mother): She did come right over to me afterwards and said, "See, I told you I don't like vegetables."

Maybe I'll give her some slack.

ISA WELSCH (Jared's Mother): Yeah, I'll have a little more empathy, I guess, at this point.

NEIL DeGRASSE TYSON: So what you're telling me is that the picky-eating children are not accountable for being picky eaters.

BOB MARGOLSKEE: It's in their genes.

NEIL DeGRASSE TYSON: It is biologically predetermined. They are innocent in this accusatory world.

So what's a parent to do with their picky eater?

Let them eat cake?

BOB MARGOLSKEE: My favorite part.

NEIL DeGRASSE TYSON: In the end, are we really held hostage by our genes?

Oh, man that's good.

Not entirely.

Remember at the beginning of my meal, when I found out just how much our senses work together to create our perception of flavor? It turns out, over time, that our sense of smell changes, and that affects our sense of taste, no matter what kind of genes we have.

In a recent study, my dining companion, Stuart Firestein found that of the thousand genes in the mouse genome used for smell, not all of them are active throughout life. Maybe the same is true for us.

STUART FIRESTEIN: And so, we think, over a lifetime, our sense of smell changes. So that something which smelled really bad, like, for example, Brussels sprouts or spinach, when we were a kid and therefore gave us a bad feeling for the taste, now smells much better.

BOB MARGOLSKEE: So young children will avoid bitter much more than the adult, and they are more sensitive and more preferring of sweet. They have a sweet tooth. They like lots of fat, lots of sugar.

NEIL DeGRASSE TYSON: What you're saying is you have a biogenetic argument for why the children's menu at every single restaurant in America doesn't have vegetables—no green vegetables—and there's always something fried and an ice cream dessert at the end.

STUART FIRESTEIN: Boy, that sounds good.

NEIL DeGRASSE TYSON: So next time you get frustrated with your picky eater, take a moment to relax and remember, their genes may be influencing their food choices just as much as you are.

On Screen Text: Take 14 hydrogen atoms, 10 carbons, one oxygen and put them together, and it smells like mint. Assemble that very same molecule in a mirror image, and the same molecule, in this configuration, smells like caraway. Why?

For the most part, both molecules bind to the same receptors, but there are another three receptors that bind only with the caraway version. And that's nothing to sniff at. Sorry.


NEIL DeGRASSE TYSON: Class, we know that some animals can learn to do all kinds of entertaining tricks. But now we're finding out that some creatures can learn and even reason in a way that's totally unexpected.

Correspondent Ziya Tong had a close encounter with a group of animals who not only go to school, they study and they're actually acing their tests!

Class!! Class!!!

Thank you.

LEAH COOMBS: Okay, Ziya come on in.

ZIYA TONG: I'm so excited.

Okay, so this was an offer I couldn't refuse...

LEAH COOMBS: Come around this way, Ziya.

ZIYA TONG: My God, what did I get myself into?

I've flown across the country for a kiss, a kiss from a walrus—all 2,300 pounds of him.

His name is Sivuqaq, and he and two females live here at a Six Flags Amusement Park in Vallejo, California. They were found abandoned in Alaska, when they were only two weeks old.

LEAH COOMBS: So here's their food.

ZIYA TONG: Leah Coombs is their trainer.

LEAH COOMBS: Do you want to grab a handful out of there?


LEAH COOMBS: Are you ready?

ZIYA TONG: I think so.

This is certainly a long way to come for a kiss.


LEAH COOMBS: So, this is Siku, right here, one of the girls.

ZIYA TONG: Hello, Siku.

And now, seeing their size, I wonder if it was such a good idea.

LEAH COOMBS: You want to give her a kiss? Give her a kiss on her cheek. Siku, target.

So lean in to her so she can get to you.

Target. Good girl. Kiss. Okay. Good girl. Blow a kiss.

ZIYA TONG: All my fears aside, these guys really know how to impress a gal.

Sit up.

Oh, get out of town! Get out of town.

As charming and funny as these characters are, some scientists say these clowns are challenging long-held assumptions about what makes humans different from other animals.

I never thought you could be so friendly.

LEAH COOMBS: Good girl. Give me a sound. Good.

ZIYA TONG: And that is what Colleen Reichmuth and Ron Schusterman study. They're trying to understand the behavior and intelligence of these marine animals and others, like seals and sea lions, that all belong to a family of fin-footed mammals called pinnipeds.

At their lab, at the University of California, Santa Cruz, they and their students work to understand the how these animals' brains function. And to do so, they run the lab much like a school for pinnipeds.

Meet the class star, Rio, a California sea lion. Definitely entertaining, but no academic slouch either.

COLLEEN REICHMUTH: Rio's really a remarkable animal. She's had about 21 years of schooling.

ZIYA TONG: Rio has some pretty remarkable classmates, too, including Sprouts, a harbor seal...


SPROUTS (A Harbor Seal): Wowowowowo.

ZIYA TONG: ...and a half-ton Northern elephant seal, named Burnyce.

COLLEEN REICHMUTH: Here you go. Good. Down.

ZIYA TONG: At this would-be-school, the animals spend their days taking tests.

COLLEEN REICHMUTH: Sea lions can pass tests that are very difficult for many other species to pass, including some of the great apes and including humans.

ZIYA TONG: Here's how it works. Rio, like a participant at a game show, sits in front of a wood set and is shown different characters, some that look like numbers, some like letters.

Rio has been taught that certain sounds, like crickets, go with a particular number or letter, like D.

So, when the buzzer sounds, she selects her answer by pointing her nose at one of the cards. If she makes the right match, she gets a fish.

Rio loves getting fish rewards and memorized very quickly that particular sounds go with particular letters or numbers. For instance, the ring of a telephone goes with B.

COLLEEN REICHMUTH: So, Rio could learn, by trial and error, that straightforward rote memorization that if she hears the ring, then she should always choose B. And she's able to make that type of association very quickly.

ZIYA TONG: Sea lions like Rio are perfect for this kind of testing because they are like, well, a dog with bone.

COLLEEN REICHMUTH: Sea lions can be very focused. They can ignore lots of other distractions, and really home in. When Rio makes an error, you may see her kind of tense up, jump in the pool, swim around. She may bark. She'll pace around a little bit. She's a bit intense.

ZIYA TONG: As any student knows, rote memorization is a useful skill in taking tests for a sea lion or a human, but it isn't all that impressive when it comes to demonstrating intelligence.

But today's test is.

COLLEEN REICHMUTH: This is J, as in jack, on the right; number 9, on the left.

ZIYA TONG: Colleen wants to see if Rio can exhibit that supremely human skill of logic.

COLLEEN REICHMUTH: So Rio had previously learned that A, B and C, that all letters could be grouped together. And now, she learned something new: that ring goes with B.

ZIYA TONG: So today, Rio is presented with a new problem. She hears the familiar ring sound, but her choices are only the letter C and the number 9, not B the answer she has been taught. Now Rio must figure out what answer will get her a fish. Very quickly, she figures out that she can substitute B with any other letter.

COLLEEN REICHMUTH: It turns out that Rio is able to use a logic rule to solve a problem that you haven't encountered before, being able to, you know, think it through and be correct on your first exposure.

ZIYA TONG: Rio scores over 90 percent on this exam, definitely an A student.

It was through experiments like this that Rio became one of the first animals to demonstrate a kind of higher order reasoning once thought limited to humans. And this kind of reasoning is also believed to be the basis for the most human of intellectual expressions: language.

So how does this research relate to the evolution of human language?

RONALD J. SCHUSTERMAN (University of California, Santa Cruz, Long Marine Laboratory): Symbols have meaning. They stand for something else. Many experiments now suggest that different types of animals have an understanding of meaning. They can comprehend the use of symbols.

COLLEEN REICHMUTH: You can make the analogy to the way we use sounds to identify certain objects in our environment. For example we use the word "car" to identify a physical shape that is a car.

ZIYA TONG: Another aspect of Reichmuth and Schusterman's research is to see if these animals can be taught to control the sounds they make, like humans do when we learn to speak. That is where our one-ton walrus friends come in.

SIVUQAQ: Ohhhhhhhhh.

ZIYA TONG: Most mammals make particular sounds only in reaction to a specific situation, like a dog that growls when it's threatened. Efforts to train apes and other land-dwelling mammals to control and modify the sounds they make have largely been unsuccessful.

LEAH COOMBS: Knock. Good. Knock, knock. Good.

ZIYA TONG: A lot of animals obviously communicate through sound, so what's different about a walrus?

RONALD J. SCHUSTERMAN: What this training shows is they have incredible control over this, so that they can learn to produce these under certain occasions and inhibit them under other occasions.

LEAH COOMBS: Give me a sound, something else, now.

COLLEEN REICHMUTH: Certainly language is very special. You know, people have always looked for reasons to separate animals from humans. Some people will tell you it's because humans have a soul, some people will tell you it's because humans have language. From my experiences studying animals, I can't point to any one feature that sets humans apart from non-human animals. The distinctions are blurred.

ZIYA TONG: Through the rigors of higher education, it seems that animals like Sivuqaq, Rio and Sprouts, are capable of surprising intellectual feats...

Oh, you deserved this one. You worked extra hard.

...and that suggests that many of the skills we considered to be uniquely human, just might not be.

On Screen Text: So Rio was able to figure this out: if greater-than is greater than B, and B is greater than C, then greater-than is greater than C. At what age is a human able to do this? 6 months? No. One year? No. Two years? No. Four years?

If greater-than is greater than B, and B is greater than C, then greater-than is greater than C.

It isn't until about four years of age that humans are able to make the associations that Rio made.


NEIL DeGRASSE TYSON: Sometimes, if something goes terribly wrong with one of your organs—let's say your liver stops working—surgeons might be able to replace it and help you survive.

But for this kind of transplant to work, you need a new liver standing by, one that somebody just donated. Internal organs like this have no shelf-life and they're hard to find. But what if we could manufacture livers, so that you could just order up a new one if you needed it?

Well, in this episode's profile, we meet a bioengineer who's trying to do just that, by figuring out how to build functioning livers in the lab, on demand.

SANGEETA BHATIA: I don't cook at all. My husband likes to say that I'm very good at "preparing" things, which means, like, heating them up. I don't keep my car very clean; my car is a mess. Right now, it smells like a dead animal.

NEIL DeGRASSE TYSON: Sangeeta Bhatia seems a lot like the rest of us.

ALICE CHEN (PhD student, Harvard-MIT): She actually is really normal.

GEOFFREY VON MALTZAHN (PhD student, Harvard-MIT): I think she's remarkably normal.

MEHMET TONER (Sangeeta Bhatia's Ph.D. Advisor): I find Sangeeta is a very normal person.

SANGEETA BHATIA: I'd like it to be that if you met me socially, you wouldn't necessarily know what I did, until I told you.

NEIL DeGRASSE TYSON: What this M.I.T. doctor and bioengineer has done isn't exactly normal. She was a pioneer in getting liver cells to function outside the human body, taking a major step toward developing an artificial liver.

Her problem-solving potential became obvious at an early age, when she performed surgery on the family's broken answering machine.

SANGEETA BHATIA: I got out the screwdriver, and took it apart, and laid all the pieces on the table, and tried to figure out what was broken. And I found something that looked amiss and fixed it. And lo and behold, the answering machine worked again. There were actually some parts left over that were supposed to belong on the inside, but it was working anyway, so I called it a day.

NEIL DeGRASSE TYSON: Sangeeta's parents emigrated from India, her father, an engineer, and her mother, one of the first female M.B.A.s in India.

SANGEETA BHATIA: My mom was, sort of, ahead of her time. She was a really independent, strong woman. If I look back on it now, she arranged her life so that she could work and contribute and still be home for us when we came home from classes.

When I was in high school, I, even like now, had a very full life. So I've always had a lot of things going on. I had a lot of really hard classes, I was twirling baton, I was dancing. I think I never really thought about the fact that it was a lot of work. I just thought about how I could do all the things I wanted to do.

NEIL DeGRASSE TYSON: And all these activities helped her to deal with the stresses of schoolwork.

SANGEETA BHATIA: You can't worry about the exam that's the next day, because you're focusing, in the moment, on learning this move. And I think what emerged from it was this, this, probably, more balanced version of me.

NEIL DeGRASSE TYSON: But after arriving at M.I.T., the harsh reality of a highly competitive, around-the-clock-work culture hit hard.

SANGEETA BHATIA: I felt, in the beginning, really out of my league, like I could never possibly work enough hours in the day. And I came to the lab one Saturday night at 3 a.m., and I noticed the lab was full of people. And I had this moment where I realized that I didn't want to be there every Saturday night at three in the morning.

Science is a marathon, and finding ways to protect part of yourself is an important part of success in the marathon.

NEIL DeGRASSE TYSON: In Sangeeta's marathon, she got a Ph.D. in biomedical engineering from M.I.T. and an M.D. from Harvard. And in the process, she applied the power of computer chip technology to tackle one of the human body's most complicated organs.

SANGEETA BHATIA: I fell in love with the liver, sort of by accident. When I was a first-year graduate student, my advisor, Mehmet Toner, had what seemed like this fascinating project, which was to make an artificial liver. It would be an off-the-shelf transplant that you could give a patient, that didn't have to come from another dying patient.

NEIL DeGRASSE TYSON: The first step toward making this artificial liver was to take liver cells from a real liver, and get them to function outside the human body, in the lab. The problem was, as soon as the liver cells were removed from the body, they immediately began to die.

MEHMET TONER: As soon as we take liver cells out of the body, put it in a laboratory environment, all bets are off. They don't function, they are not happy. And Sangeeta's problem was to tackle that.

NEIL DeGRASSE TYSON: She saw that inside the body, the liver cells branched off into stripes. Since cells communicate with one other through chemical signals, this striped pattern could be crucial.

SANGEETA BHATIA: The hypothesis was tissue architecture should matter, but no one had ever done the experiment to show that that was the case.

NEIL DeGRASSE TYSON: The challenge now was to get the tiny liver cells to obediently line up on a slide, in the lab, exactly as they do in the human body.

Combining her backgrounds in biology and engineering, Sangeeta turned to the technology used in producing the tiny patterns on computer chips.

SANGEETA BHATIA: If you've ever seen a picture of a computer chip, and it has all these networks of wires that make circuits—that technology that makes those patterns works by shining light on a surface.

NEIL DeGRASSE TYSON: Using the same technique, creating a chemical reaction with light to etch striped lines onto glass slides, she hoped to corral the liver cells into formation.

SANGEETA BHATIA: For about a year I tried this. Turned out, for my liver cells, nothing actually worked. At one point in the process, I started to think I was losing my mind, because the experiment was, you take this piece of glass that's clear, and you shine light on it, and it's still clear. And you dip it in a bunch of clear solutions, and you pour cells on it, and at the end they're supposed to organize. After you do this about a thousand times, and you never see organized cells, you start to the think that you're insane.

NEIL DeGRASSE TYSON: After laboring over her experiment for a year, one day, everything changed.

SANGEETA BHATIA: The moment that I looked into the microscope and saw the...that this thing that I had invented in my head had actually come to fruition was amazing.

NEIL DeGRASSE TYSON: With the cells lined up properly, their communication system was working. Not only were the micro-livers functioning, they were now living for an unprecedented six weeks, outside of the human body.

MEHMET TONER: It enhanced our understanding of liver biology significantly. She figured out that if you put liver cells on a surface in a certain, specific geometric configuration, bingo! Liver cells start functioning.

NEIL DeGRASSE TYSON: Soon, these micro-livers could be used to test experimental vaccines for malaria. And Sangeeta hopes that within her lifetime, she can create a functioning, artificial liver, to save patients with liver failure. But to do this, she needs a lot of help.

SANGEETA BHATIA: I have a ton of support. I have a babysitter at home, an assistant at work, and somebody who helps run the lab, and a husband that's supportive and parents that are nearby. So, it sort of takes a village to help me run my life.

NEIL DeGRASSE TYSON: It's this team of people that gives her more time to spend with her two daughters. And she makes certain that her daughters have the same kind of positive role models that she had growing up.

And in her family, Barbie(TM) is not one of them.

JAGESH SHAH (Sangeeta Bhatia's Husband): Barbie is kind of persona non grata in our house.

SANGEETA BHATIA: Barbie, in our house, is "that doll that Mommy doesn't like." Barbie really represents the exaggerated figure, the "I don't like math." And so, when I had girls, I really didn't want Barbies in the house. I didn't want that body image, I didn't want that focus on materialism—I just didn't, you know, like anything about Barbie.

NEIL DeGRASSE TYSON: Instead, she gave her daughters a Marie Curie doll.

SANGEETA BHATIA: The cool thing about Marie Curie is that she was, of course, the first Nobel Prize-winning woman. She was also the mother of two little girls. And her older daughter went on to win the Nobel Prize herself.

JAGESH SHAH: Oh, my goodness, that went down really fast.

SANGEETA BHATIA: Right to the bottom. Which one is denser?

SANGEETA BHATIA'S DAUGHTER: What does "denser" mean?

SANGEETA BHATIA: I don't think that science is necessarily a career for everyone. I want to share with them a curiosity for the way the world works, and I think whatever they want to be, they should be.

JAGESH SHAH: What's happening now?

SANGEETA BHATIA'S DAUGHTER: It's getting sparkly.

NEIL DeGRASSE TYSON: And it's not just her own daughters that she wants to inspire.

SANGEETA BHATIA: Keys to Empowering Youth was an outreach organization that I helped to start when I was in graduate school.

ALICE CHEN: We see these young girls come in and get so excited to put on lab coats and lab goggles and work with the equipment. And I think that it does make them think about choosing science and engineering as a career, and at least shows them that they have that option.

GEOFFREY VON MALTZAHN: I think Sangeeta is a wonderful role model for women, but she's a terrific role model for anybody. One of the hardest things in life is to make a clear distinction between how much time you're going to dedicate to your work, and how much time you're going to dedicate to your family and your friends. And she is able to manage both of those with a sense of ease that I think is inspirational, independent of whether you're a man or a woman.

ALICE CHEN: Once, when I was at Sangeeta's house, I was sitting with her at her dining room table, and I said, "Wow, this is place is lovely. I can imagine you working here." And she said, "Why? I don't work all the time at home. I have a life. I have my kids." I think that she just always reminds us that life is more than just work.

SANGEETA BHATIA: It is a lot of work to be a mom, and it is a lot of work to run a lab, but I don't really think about the fact that it's a lot of work; I just try and figure out how to make them all fit together.

On Screen Text: Remember Fantastic Voyage? Scientists miniaturized a submarine so that it could be injected into a patient, so they could perform surgery from the inside. Sangeeta's working on a way to perform surgery on a similar scale from the inside, as well.

By injecting tiny particles that bind to cancer cells, doctors may one day be able to image cancer cells, deliver drug therapies, and kill cancer cells, all without invasive surgery.

Downside? No Fantastic Voyage for Sangeeta.


NEIL DeGRASSE TYSON: Every creature on Earth does the same thing. We take in oxygen and then give out carbon dioxide, with the same breath. And while we're putting out CO2, trees, like this one, and other plants are sucking it right up. They need it to survive!

But with worldwide population growth and increased fossil fuel consumption, we're now putting out more CO2 than our trees and plants can absorb. And since CO2 is a greenhouse gas, there're fears that all this carbon dioxide is heating up our planet.

For some the solution is obvious. Correspondent Peter Standring met up with some inventors trying to design a very "green" machine, one that can "make like a tree..."

PETER STANDRING (Correspondent): In a warehouse on the outskirts of Tucson, Arizona, Professor Klaus Lackner has come up with an idea even he admits is a bit fantastic. He's attempting to compete with Mother Nature.

KLAUS LACKNER: We are trying to mimic what a tree can do. And these are the leaves of that tree.

PETER STANDRING: Mimic a tree?

KLAUS LACKNER: Some people would say this can't possibly be done, but then, on the other hand, every tree can do it.

PETER STANDRING: Every tree, in fact every leaf, is like a tiny factory, taking in carbon dioxide from the air and using it to make the energy it needs to survive. In the process, it releases the oxygen that we need to live.

Klaus's version of a tree also pulls carbon dioxide out of the air. Not for its own survival, but to help us fight global warming. Sounds pretty incredible? Well, so is the way he came up with the idea.

It all started a decade ago, when his 12 year-old-daughter, Claire, came to him for advice.

KLAUS LACKNER: When I started to think about this problem, I was looking for ways of doing experiments. And, just about that time, Claire came to me in the study at home and said she is looking for an experiment to do for her science fair.

CLAIRE LACKNER (Student, Princeton University): I was in middle school, and I had to do a science experiment for my science class. And so I talked to my dad about various ideas and he suggested this.

KLAUS LACKNER: I said, "Why don't you pull CO2 out of the atmosphere?"

PETER STANDRING: Pull carbon dioxide out of the air? A tall order for a little girl. But, as the daughter of a renowned scientist, Claire already knew about global warming. She understood that when sunlight enters the atmosphere and strikes the Earth's surface, some of it is reflected back towards space in the form of heat.

Greenhouse gases like CO2, carbon dioxide, work like a chemical blanket to trap heat and keep the planet nice and warm. But the increased burning of fossil fuels was generating so much carbon dioxide that our planet's temperature appeared to be rising at an alarming rate.

But how could you just pull CO2 out of the air?

PARROT: Hello.

PETER STANDRING: Claire had an innovative idea.

CLAIRE LACKNER: I went to the local pet shop and bought a fish pump. I filled a test tube with sodium hydroxide. Next, I attached the fish pump to the test tube, turned it on and ran air through it all night.

PETER STANDRING: As Claire slept, her experiment was hard at work. The fish pump was forcing air containing a small percentage of CO2 into the test tube.

CO2 is an acid, much like vinegar. Sodium hydroxide, the liquid in the test tube, is a base, kind of like baking soda but stronger, a lot stronger. It's made of lye; the nasty stuff that cleans out your drain.

When acids and bases meet, they not only attract, but they bind to each other. It's called an acid-base reaction.

CLAIRE LACKNER: So the carbon dioxide binds to the sodium hydroxide and leaves the air.

PETER STANDRING: Claire succeeded in capturing carbon dioxide straight from the air, won a prize at the science fair, and changed the course of her father's life.

KLAUS LACKNER: I was surprised that she pulled this off as well as she did, which made me feel that it could be easier than I thought.

The first sketch I made ended up looking like a tuning fork or a goal post with Venetian blinds.

PETER STANDRING: A far cry from Mother Nature's design.

KLAUS LACKNER: The first reaction of most people, is, "Why take CO2 out of the air, where it's more dilute than in any other place? Clearly, it must be easier to get it out of a power plant." But not all of the CO2 comes out of a power plant.

PETER STANDRING: A lot comes from cars, trucks and airplanes burning fuel. Once in the air, CO2 is very dilute, making the idea of capturing it sound close to impossible.

If Klaus was going to make this far-out idea a reality, he was going to need some practical advice.

KLAUS LACKNER: If you look at Claire's experiment what she had is a test tube.

PETER STANDRING: So he went to the Wright brothers, not Orville and Wilbur, but project manager and engineer Allen and Burton, another set of brothers, who, like their namesakes, don't shy away from a challenge.

ALLEN WRIGHT (Global Research Technologies): The Wright brothers were able to look at a bird in flight, so they knew it was possible to fly. Klaus and I will look at a tree and say, "Well, you know, that tree is capturing carbon dioxide out of the air. We know it can be done; got to figure out how to do it."

PETER STANDRING: Not just in the laboratory with a tiny fish pump and a test tube, but on a global scale.

In 2004, they form a private company called G.R.T.

But the transition from a child's science fair project to the first synthetic tree is filled with obstacles. One, in particular, could stop them dead in their tracks. Their tree needs electricity to run. And whenever you produce electricity by burning oil, gas or coal, you also produce carbon dioxide. It's called an energy penalty.

If their synthetic tree produces more CO2 to run than it can capture, well, what's the point?

A delicate balancing act begins. For every choice the team makes there is a price to pay, an energy penalty. Can they somehow reduce the amount of energy they use?

KLAUS LACKNER: We needed to come up with a shape where you don't have to have an aquarium fish pump driving all the air through the system, but to have the wind just deliver the air and pass it through the collector.

PETER STANDRING: It all comes down to geometry. What is the size and shape of the perfect synthetic leaf, one that can remove the most CO2 from the air?

To find out, they construct a wind tunnel to study how air moves around and through a variety of surfaces.

KLAUS LACKNER: The easier it is to get air through, the more CO2 we can collect.

ALLEN WRIGHT: We tried an array of strings; we tried screens; we tried vertical plates of solid material that were smooth; we tried vertical plates that had a knobby surface.

PETER STANDRING: With each attempt, they measure the air pressure in the wind tunnel. A drop in pressure means the airflow has stopped, and that sample has failed.

ALLEN WRIGHT: this is not the answer.

PETER STANDRING: It takes a year to find a shape that lets enough air pass through.


PETER STANDRING: It turns out to be long flat sheets.

ALLEN WRIGHT: The air would move through with very little resistance. It worked well.

PETER STANDRING: So air can move through their manmade leaves, but how will they capture CO2?

At first they follow Claire's lead, coating the leaves with sodium hydroxide. The chemistry is sound, but it's a nasty business.

ALLEN WRIGHT: It'll be a much tougher job for us.

KLAUS LACKNER: Sodium hydroxide is great to prove it can be done, but it has so many disadvantages.

ALLEN WRIGHT: Sodium hydroxide is a very corrosive material, it's not a good idea to get it on your skin; it's very harmful if you were to get it in your eyes. As a practical matter, trying to build a machine that works on sodium hydroxide would force us to use very expensive materials. It would drive the cost up significantly.

PETER STANDRING: The guys decide to abandon the idea of using sodium hydroxide when they make a startling discovery: this material. Now, exactly what this material is, the guys aren't telling.

BURTON WRIGHT: What is it?

ALLEN WRIGHT: Do I have your attention?

BURTON WRIGHT: We can't tell you.

PETER STANDRING: Turns out this is where science and commerce collide. Its true identity is proprietary, that is, until their patent comes through.

The team claims that this engineered fabric attracts CO2 just like sodium hydroxide, but with none of the pitfalls.

Here's how the system works: the nine-foot synthetic tree opens its doors, letting air flow through its leaves, which, thanks to their mystery material, readily absorb carbon dioxide. The leaves are then sprayed to wash the CO2 away for storage.

The process does use electricity, but, in the future, they hope, green power will make the device even more energy-efficient.

Still one big question remains: what to do with all that CO2.

One option lies miles from civilization. Since 1996, a Norwegian oil company has gotten a lot of practice getting rid of CO2 by pumping it into an aquifer deep beneath the North Sea. The process is called carbon sequestration. But could the carbon leak out? If so, what effect would it have on marine life?

MARTIN HOFFERT (New York University): Once you've got enough gas under there, and it's leaking out, it could become a very serious problem.

PETER STANDRING: And how much CO2 can they put down there anyhow?

KLAUS LACKNER: I believe, in the long term, underground injection will not quite have the capacity we're looking for, so I am looking at another process which I refer to as mineral sequestration.

PETER STANDRING: There's a perfect example of it in New York City, on the campus of Columbia University, underneath a bronze statue of the school alma mater.

KLAUS LACKNER: She is sitting on this pedestal of serpentine rock. This serpentine has absorbed CO2, probably out of rainwater. It's known as geological weathering, and if you wait long enough, that's what will happen to all the CO2 we make.

PETER STANDRING: But it takes hundreds of thousands of years for Mother Nature to pull off geological weathering, and we don't have that long to wait, so Klaus is trying to figure out a way to speed it up in the lab.

As for his tree? He now has a working prototype, but many questions remain unanswered. Like, how well will it survive the elements? And who's going to a pay for it?

Is Klaus's tree too fantastic to be real?

MARTIN HOFFERT: You could have said that about the Wright brothers and Thomas Edison.

I can't sit here and tell you now that this is going to work. I can tell you now that it would be a terrible mistake not to do the research to find out.

KLAUS LACKNER: I believe that it is impossible to stop people from using the fossil fuels, so we need to develop technologies which allow us to use them without creating environmental havoc on the planet.

CLAIRE LACKNER: We are, as a world, changing the climate and changing the Earth. And we need to understand how we are changing it, and we need to understand what we would do: either how to fix it or to control how we change it.

On Screen Text: How many pounds of CO2 does a human breathe out every year? Four-hundred-seventy-six-pounds. And how many pounds of CO2 does a tree absorb every year? Sixty-four pounds. How many trees to absorb 1 person's exhaled CO2? Seven.


NEIL DeGRASSE TYSON: And now for some final thoughts on coming to our senses. We're born with five senses. You know each of them: we hear, smell, touch, see and taste the world around us. These are the five, and the only five ways we obtain information.

In spite of the praise they receive, our senses are incomplete. For example, we have no built-in way to register magnetic fields or radioactivity. And we're practically blind, when you consider all the forms of light we cannot see, including infrared, ultraviolet, and radio waves, even though they are all around us.

And often our five senses are just plain unreliable. Eyewitness testimony, though high evidence in the court of law, is the lowest form of evidence in the court of science.

When we declare a food to be bitter or sweet, we hardly ever recognize that it's an opinion derived from our genetic profile. More typically, we wrongly presume these features to be intrinsic properties of what we tasted.

That's why it's hard to do science equipped with only our senses. The most successful fields of research are those rich in methods and tools of measurement that do not depend on the genes of who's doing the measuring.

In this way, scientists reveal fundamental truths about the universe, allowing us to decode and even predict the operations of nature. Otherwise, if all you have are your five senses, then all you have are your opinions.

And that is the cosmic perspective.

And now we'd like to hear your perspective on this episode of NOVA scienceNOW. Log on to our Web site and tell us what you think. You can watch any of these stories again, download additional audio and video, explore interactives, hear from experts. And, if you want to get the advance scoop on upcoming broadcasts and find out what goes on behind the scenes, sign up for the weekly e-newsletter at

That's our show. We'll see you next time.

Stay tuned for scenes from the next NOVA scienceNOW, but first...

Funding for NOVA scienceNOW is provided by the National Science Foundation, where discoveries begin. And...

Discover new knowledge; biomedical research and science education; Howard Hughes Medical Institute: HHMI.

And the Alfred P. Sloan Foundation, to enhance public understanding of science and technology and to portray the lives of men and women engaged in scientific and technological pursuit.

And the George D. Smith Fund.

And by PBS viewers like you. Thank you.

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