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NOVA scienceNOW: July 7, 2009

PBS Airdate: July 7, 2009
Go to the companion Web site

NEIL DeGRASSE TYSON (Astrophysicist/American Museum of Natural History): On this episode of NOVA scienceNOW:

...no, it's not moving day at the planetarium.

Telescope number 7.

These new telescopes are searching for the cosmic Holy Grail: alien planets that can support life.

GEOFF MARCY (University of California, Berkeley): We want to find Earths. We want to know whether we're alone.

NEIL DeGRASSE TYSON: Can this ambitious astronomer, working with simple equipment...

No matter how high-tech the operation is, never leave home without duct tape.

...and dealing with unexpected guests...

DAVE CHARBONNEAU (Harvard-Smithsonian Center for Astrophysics): Those appear to be paw prints.

NEIL DeGRASSE TYSON: Paw prints?

...be the first to find a new world where life could exist?

DAVE CHARBONNEAU: If you find one habitable planet, that's a huge discovery!

NEIL DeGRASSE TYSON: And one of these two paintings is a van Gogh original, worth millions, the other, a fake, created by this artist for a NOVA scienceNOW computer challenge.

CHAD COHEN (Correspondent): Do you think she has a shot against the computers?

ELLA HENDRIKS (Head of Conservation, Van Gogh Museum): I think it will be a challenge, yeah.

NEIL DeGRASSE TYSON: Three teams of computer scientists come up with programs to pick out our fake among five van Gogh originals.

ERIC POSTMA (Maastricht University): These are genuine van Goghs.

NEIL DeGRASSE TYSON: Will this new technology work? The results may surprise you as much as they did us.

Also, in this episode's profile, you'll meet a biologist studying some spiders whose mating habits are to die for.

MAYDIANNE ANDRADE: She'll actually pierce him and eat him while he's mating with her.

NEIL DeGRASSE TYSON: Why would any creature behave this way?

MAYDIANNE ANDRADE: It's what evolution's all about, right? It's sex and it's death, and it's all wrapped up into one really interesting story.

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.

HUNT FOR ALIEN EARTHS

NEIL DeGRASSE TYSON: Hi, I'm Neil deGrasse Tyson, your host of NOVA scienceNOW. Wouldn't it be cool, if the universe were like it is in a lot of movies: filled with aliens, even intelligent life that we could meet, socialize with?

Hey, mind passing the nuts?

But if there are other creatures out there, where would they be? We've been searching the skies for a while now to find planets other living things could call home. And now, planet hunters say they're tantalizingly close to that goal.

Not nuts.

GEOFF MARCY: Most of us, when we're children, we look up into the night sky and we wonder, "What is our place in the universe? Are we somehow related to the stars, the planets? Are there other beings out there?"

The Holy Grail for me and all of the astronomers working in my field is to find an Earth-like planet and especially a habitable Earth-like planet.

NEIL DeGRASSE TYSON: Geoff Marcy has spent his career hunting for other worlds, but it's clear that not every world is friendly to life as we know it.

GEOFF MARCY: What renders a planet, indeed, suitable for life? Well, clearly, you want a planet that has some water on it, because water is the cocktail mixer that allows the chemistry of our bodies to even work.

NEIL DeGRASSE TYSON: If we want a planet with liquid water, then it can't be too close to its star; that would make it too hot, and the water would boil away. And it shouldn't be too far away, either; too cold, and you'll likely get an ice ball.

What everybody really wants to find is a little rocky planet, whose distance from its star is juuust right, a "Goldilocks" planet with oceans of liquid water. But hunting down a planet just like ours has been a daunting task. In fact, not long ago, we hadn't found any planets beyond our solar system, none at all. They're so far away and so dim, they get lost in the glare of their own suns, the stars they orbit.

LISA KALTENEGGER (Harvard-Smithsonian Center for Astrophysics): It's like a lighthouse and having a tiny firefly next to the beam of this lighthouse; this is what you're looking for.

NEIL DeGRASSE TYSON: So to improve their chances, most planet hunters, like Geoff Marcy, focus on stars.

GEOFF MARCY: Here we go, first star, shooting. Wow, it's beautiful. Okay, we can go to the next star.

NEIL DeGRASSE TYSON: Using the big, powerful Keck Telescope, in Hawaii, Geoff looks for slight wobbles in a star's position, signs that a planet might be orbiting.

GEOFF MARCY: These planets do one thing that is just glorious. They're so massive that, as they orbit the star, they pull gravitationally on the star. So if you just watch the star, you see it move to and fro.

NEIL DeGRASSE TYSON: This so-called "wobble method" of planet hunting is a little bit like watching people walk their dogs.

GEOFF MARCY: You watch the dog owner—never mind the dog itself—and the dog owner gets kind of yanked around as the dog goes to and fro.

NEIL DeGRASSE TYSON: The idea is you don't have to see the dog itself to know I'm getting yanked on by something.

GEOFF MARCY: And of course, that's what we do. We watch stars that are being yanked on by their host planets and, of course, in that case the leash is gravity.

NEIL DeGRASSE TYSON: Thanks to the wobble method, Geoff and other hunters have, so far, tracked down hundreds of planets. Most of them are enormous balls of gas, like our Jupiter—which itself has 300 times the mass of Earth—and some orbit extremely close to their stars.

GEOFF MARCY: They're so close, skimming along the surface of the host star, that these planets are blowtorched to 1,000, 1,500 degrees. So they're so hot that the organic molecules of which our bodies and other life forms on the earth are made would disintegrate.

NEIL DeGRASSE TYSON: It turns out, if we want to find more comfortable Goldilocks planets like Earth, there's a little problem with the wobble method. If a hot Jupiter is like a big dog yanking on its owner, then Earth is kind of like this.

It might be full of life and totally lovable, sure, but gravity-wise, it's kind of wimpy. It's just not going to have much of an influence.

If you're only watching me, you might never know the dog was there. Same goes for a star out in the galaxy. The teeny tiny wobble caused by an orbiting Earth is really hard to detect, and that's why, despite all their successes...

GEOFF MARCY: So far, we astronomers haven't found a single Earth, not one.

NEIL DeGRASSE TYSON: ...if we want to find a place for life, we might need another method.

Recently, I headed up to Mount Hopkins in Arizona to meet another planet hunter, one who's using an entirely different approach in the search for habitable worlds.

Dave Charbonneau's experiment is based in an old shed, once used to track Soviet satellites during the Cold War. As planet-hunting projects go, this one is relatively low budget, because, unlike the wobble-hunters, he doesn't need the biggest, most powerful telescopes.

You know, when I walk into big observatories, I expect big telescopes. These look kind of puny to me.

DAVE CHARBONNEAU: But there are lots of them.

NEIL DeGRASSE TYSON: Dave can use smaller, cheaper telescopes, because, in his search for habitable worlds, he's not looking for a wobble at all.

DAVE CHARBONNEAU: It may be easier, instead of looking for the wobble, to actually look for an eclipse.

NEIL DeGRASSE TYSON: We can see this kind of eclipse, or transit, right here in our own solar system, when Venus or Mercury passes between Earth and the Sun. But when the planet and its star are light-years away, you can't see a round silhouette, but sometimes the star will appear to dim ever so slightly.

DAVE CHARBONNEAU: Then...so, the idea is as the planet passes around in front of the star, then it'll block some small part of the light. And so, we'll measure this little miniature eclipse. Essentially, we'll measure that the star will get fainter for a short period of time.

NEIL DeGRASSE TYSON: These kinds of transits are pretty rare, so Dave is casting as wide a net as he can, tracking a couple of thousand stars. That's why he needs a lot of telescopes.

Today, Dave and his team recruited me to help set up a few more.

Telescope number 7.

DAVE CHARBONNEAU: This number 7? First thing we need is the mount.

NEIL DeGRASSE TYSON: Let's do it.

No matter how high-tech the operation is, never leave home without duct tape.

DAVE CHARBONNEAU: Well, this is the power cable.

NEIL DeGRASSE TYSON: Power cable.

DAVE CHARBONNEAU: And this is the data cable. Power goes in, planets come out.

NEIL DeGRASSE TYSON: Using this new transit method, Dave has already discovered several new planets, but so far they're all the size of Jupiter, or bigger, and not habitable. Now, he's hoping to improve his chances of finding a small, Goldilocks planet by focusing his telescope on a particular kind of star, called a "red dwarf."

Red dwarfs are much, much smaller and dimmer than our sun, so, if a small planet passes in front of a red dwarf, it will block out a larger percentage of its light than if it crossed in front of a bigger star, like our sun.

As sundown approaches, the roof of the shed slides away. And when the stars appear, the telescopes go to work, swooping around to point at one red dwarf and then another, hunting for any trace of a transiting planet.

The telescopes are designed to do their job alone on the mountaintop, but I saw evidence that they might have some visitors.

Oh, wait, stop. There's smudges on this mirror.

DAVE CHARBONNEAU: Yeah. Unfortunately, those appear to be paw prints.

NEIL DeGRASSE TYSON: Paw prints?

DAVE CHARBONNEAU: Yeah, we've come to realize, recently, that it appears that some animal is coming in here, perhaps during the night, and maybe looking at itself in the mirrors.

NEIL DeGRASSE TYSON: Dave hasn't discovered the culprits yet, but whoever they are, they haven't stopped the telescopes from gathering thousands of images of stars.

As the pictures come in, a computer immediately analyzes them, looking for the slightest dimming.

But the telescopes will only see it if the planet's orbit is aligned just right, so that it passes between us and the red dwarf star. So you need star systems that are edge-on to our view.

DAVE CHARBONNEAU: Right.

NEIL DeGRASSE TYSON: And you don't know that yet about your 2,000 stars.

DAVE CHARBONNEAU: That's right.

NEIL DeGRASSE TYSON: It sounds like it's a challenge.

DAVE CHARBONNEAU: That's right. We are looking for the needle in the haystack. But, if you find one habitable planet, that's a huge discovery. That's worth it. That justifies all of this.

NEIL DeGRASSE TYSON: Okay.

Dave has high hopes that the transit method is a great way to find habitable worlds, and he's not alone. After years of preparation, NASA just recently launched the Kepler space telescope.

Over the next three or four years, Kepler will be looking towards the constellation Cygnus, keeping watch on about 100,000 Sun-like stars, searching for transiting planets.

Since it's high above Earth's blurry atmosphere, Kepler has the ability to find a planet pretty much like our own, orbiting a star just like our sun.

GEOFF MARCY: We want to find Earths. We want to know whether we're alone. And Kepler is the first mission that can find true twins of our earth: Earth-mass planets, Earth-size planets, that orbit in an Earth-like distance.

NEIL DeGRASSE TYSON: Of course, if and when we locate a livable planet, we'll want to know, is anybody home? And when I say "anybody" I don't necessarily mean one of these movie guys. I'd be thrilled with signs of microbes.

As we sniff out the chemistry of life on distant worlds, eventually, we should answer that question, too. And the cool thing is, pretty soon, we'll know just where to look.

LISA KALTENEGGER: We are just at the verge of finding these planets. We can answer a question that was asked thousands of years ago—maybe in five years, maybe in 10—but we'll answer it.

GEOFF MARCY: We should know, within our lifetimes, whether there are other Earths and whether some, or most, of them are habitable, like our own earth. What a, what a lucky time to be alive.

On Screen Text: In the mid-19th century, astronomers noticed that Uranus wasn't orbiting the way it should...like this.

It was wobbling like this.

Why?

Something mysterious was pulling on it.

And when they pointed their telescopes to that mysterious spot, they saw another planet. And they named it Neptune. It was the first time a planet was discovered in a way other than direct observation.

ART AUTHENTICATION

NEIL DeGRASSE TYSON: How do you identify a true masterpiece? We don't usually think of a great painting as something that can be reduced to numbers.

Got a couple more threes right over here.

But a few scientists might disagree. They say that if you take away the color and break down a painting, brushstroke by brushstroke, you'll find a complex pattern of numbers, a pattern unique to every artist. And as correspondent Chad Cohen reports, it could provide a crucial clue if you're trying to tell the real thing from a clever forgery.

CHAD COHEN: Deep in the storage vault of the Van Gogh Museum, in Amsterdam, a precious canvas is being photographed. The Reaper, painted by Vincent van Gogh in 1889, has the thickly layered paint and bold curves the artist is so famous for.

But are we looking at the real thing? Because there are two Reapers in this vault, one, as you might expect, worth millions; the other, a copy, worth no more than the oil and canvas it was painted with. Can you tell the difference? It's something hundreds of collectors ask the Van Gogh Museum to do every year, convinced they own a masterpiece by the great artist.

SJRAAR VAN HEUGTEN (Head of Collections, Van Gogh Museum): We get many questions for expertise here. Our opinion is asked all the time. And there are many fakes that have been around for decades. That is a problem for any renowned artist because money, of course, is very tempting.

CHAD COHEN: This is serious money: 50, 70, 80 million dollars a piece for some of the best known paintings. Even the Van Gogh Museum was fooled into buying a fake back in the 1970s. It's a 19th Century painting called View of the Ij, Amsterdam's inner harbor. It wasn't originally intended as a fake, but years later someone forged van Gogh's signature onto the canvas.

So how do you determine if a painting is the real thing? In May of 2007, the Van Gogh Museum explored one of the latest scientific methods of art analysis, by hosting the first international workshop on computer image processing.

ERIC POSTMA: These images are represented in terms of numbers.

CHAD COHEN: Eric Postma directed the technical presentation.

ERIC POSTMA: The purpose of the project was to look at these paintings and try to determine if we could distinguish between real and fake van Goghs.

CHAD COHEN: The computer scientists focused on one of the most revealing traits of van Gogh's work. As the museum's head conservator, Ella Hendriks showed us, it's the way he applied paint to his canvas.

ELLA HENDRIKS: I would tend to really want to get close and look at these, for example, these very nice white strokes, in the foreground, that were added at a late stage. If you look very close, you can see these, sort of, trailing drips of paints, as he literally scooped up the paint from the canvas, lifting his brush and then carrying the trail of paint.

CHAD COHEN: It turns out that van Gogh's brushstrokes are crucial markers, not only for critics and connoisseurs, but for computers as well.

ERIC POSTMA: The pattern of brushstrokes is very specific and very indicative of a painter. So the first selection that you make when you start to analyze these paintings digitally is to select the level of individual brushstrokes.

CHAD COHEN: The computer scientists create programs which examine a painting from different angles, to determine the direction of each brushstroke. Collecting the brushstroke patterns from more than 100 paintings establishes a baseline for van Gogh's style. But could the computer be fooled? Could an artist, specially trained to copy the old masters, duplicate van Gogh's style?

To find out, we commissioned Charlotte Caspers to carefully imitate every detail of van Gogh's brushstrokes. She's an expert in art reconstruction, using historical materials to copy famous paintings so museums can decide how to preserve the originals.

CHARLOTTE CASPERS (Artist and Conservator): The best would have been to sit next to the painting, but well, that was just not possible.

CHAD COHEN: The Van Gogh Museum doesn't allow artists to paint in front of the originals, so she made her own photos of The Reaper.

CHARLOTTE CASPERS: I couldn't bring the painting home, so I had to take a picture. And when it's a digital one, you can blow it up on your computer. So that is what I did.

CHAD COHEN: Knowing that the scientists would be focused on the pattern of van Gogh's brushstrokes, Charlotte's job was to perfectly match his technique.

CHARLOTTE CASPERS: I had a picture next to my canvas I was painting on. And I could blow that up so I could have a close look at the paint surface of the original painting from a picture.

CHAD COHEN: How do you think that trying to be him ultimately influenced the painting itself?

CHARLOTTE CASPERS: It's less spontaneous.

I was just switching all the time, my eyes, from my canvas to the picture and trying to do what he did.

CHAD COHEN: We had a young artist copy one of the master's paintings. Did you, did you get to see the copy?

ELLA HENDRIKS: I did get to see it, yeah.

CHAD COHEN: What'd you think?

ELLA HENDRIKS: I think she did a remarkable job because it's very...she's made a very accurate copy of the rhythm of the brushstrokes but managed to do it in a spontaneous way.

CHAD COHEN: So do you think she has a shot against the computers?

ELLA HENDRIKS: I think it will be a challenge, yeah.

CHAD COHEN: The challenge begins by turning Charlotte's copy of The Reaper into a color photograph, which is then turned into a high-resolution black and white scan.

Identified only by catalogue number, it takes its place beside five real van Gogh paintings, creating NOVA scienceNOW's test for three computer teams: Penn State University, Princeton University and Maastricht University. Eric Postma leads the Maastricht team.

So, here's a famous van Gogh.

ERIC POSTMA: Yeah.

CHAD COHEN: Van Gogh.

ERIC POSTMA: Van Gogh.

CHAD COHEN: Van Gogh.

ERIC POSTMA: Van Gogh.

CHAD COHEN: Van Gogh: The Sower.

ERIC POSTMA: The Zier.

CHAD COHEN: However you want to say it.

How do you begin? So you look at this, it's a beautiful painting. But you're going to strip it of its beauty, one layer of its beauty right now?

ERIC POSTMA: Yeah. In fact, what it'll be, because we translate the entire painting into numbers...

CHAD COHEN: Postma's software scans the whole painting, identifying areas of contrast. The more contrast, like the dark tree branch against the light sky, the larger the number assigned by the computer.

If the contrast is less extreme, like the edge of the sun against the sky, the number is smaller. When all the contrast patterns are combined, a statistical portrait of van Gogh's style is created.

ERIC POSTMA: Well, these are genuine van Goghs. And this is a known fake. The faker tried too hard to mimic van Gogh.

CHAD COHEN: And by trying too hard, that means?

ERIC POSTMA: Too much.

CHAD COHEN: Painting too much?

ERIC POSTMA: Too much, exactly.

CHAD COHEN: I see. Someone copying van Gogh paints too many brushstrokes to get it right, and the computer identifies them as areas of higher contrast. First the program analyzes the brushstrokes from six different angles then combines them to reveal areas where they overlap. More overlapping brushstrokes show up as brighter areas; fewer overlaps are dark.

Look at this famous painting van Gogh did of his bedroom. As the computer separates out each angle, it highlights the brushstrokes painted in that direction. Putting them all together reveals a brushstroke map of the painting.

Now look at the forgery. The computer identifies more overlapping brushstrokes in every direction, 10 times as many as the van Gogh bedroom. The genuine van Gogh paintings display fewer brushstrokes than the forgery.

ERIC POSTMA: If you deliberately try to mimic van Gogh, then it's not natural anymore, and then you tend to overdo it. And this overdoing it results in high numbers. And that could be one way of detecting a fake.

INGRID DAUBECHIES (Princeton University): I'd like to see what zoom-in gives there.

CHAD COHEN: Ingrid Daubechies and the Princeton team have also been looking at the six paintings in our test, searching for the fake.

INGRID DAUBECHIES: If you try to make a copy, you would pay so much attention to what you're doing that you probably paint it more slowly and with more restrained hand than van Gogh himself would have painted, and we expect that to transfer, as well.

CHAD COHEN: For James Wang and Jia Li from Penn State University, Charlotte's copy seemed to blend in with the other five paintings.

JIA LI (Pennsylvania State University): Just by looking at the pictures, they all look very van Gogh, so that's why, later, we also tried a statistical modeling approach.

CHAD COHEN: All of the science teams had less than a week to distinguish the fake from the real van Goghs.

Would they pick The Sunflowers? The Sower? Any of the other three genuine van Goghs? Or would any of their computer programs successfully choose Charlotte's version of The Reaper? The analysis is finished, and it's time to take her painting to the Van Gogh Museum, where the scientists are waiting.

Okay, the moment of truth. Do you all have an answer? We're ready to bring in the artist? Okay, Charlotte. This is Charlotte Caspers. She painted the painting that you guys tested.

INGRID DAUBECHIES: Very nice to meet you.

CHAD COHEN: Do want to come on over and reveal it? Well, bring it on over. Don't open it yet. Bring it. Bring it on over, Charlotte. All right, so what do you all got?

JAMES WANG (Pennsylvania State University): Six-eighty-seven.

CHAD COHEN: Six-eighty-seven.

INGRID DAUBECHIES: Six-eighty-seven, the one...

CHAD COHEN: You guys match. That's two for 687.

ERIC POSTMA: And that's three for 687.

CHAD COHEN: All right. That's your final answer? You're sticking with it?

INGRID DABUECHIES: Yes.

CHAD COHEN: All right. Charlotte, let's see.

INGRID DAUBECHIES: Yes, yes, yes. Yes. Yes!

CHAD COHEN: Six-eighty-seven, The Reaper.

SHANNON HUGHES: Oh,yes. Got it. Got it!

JAMES WANG: So how long did it take you to finish the painting?

CHARLOTTE CASPERS: I worked two days on this one.

ERIC POSTMA: How long did it take you to analyze the painting?

JAMES WANG: Oh, we took two days, too.

CHAD COHEN: In fact, van Gogh himself completed many of his most famous paintings in two days or less, and they've kept art collectors and experts busy for more than a century. They're not there yet, but computers will ultimately speed the process along.

ERIC POSTMA: The most valuable thing about these techniques is that it can help art experts. You just can scan over the entire painting. And they do it in a completely unbiased way, and that's the great advantage of computers.

On Screen Text: We asked Eric Postma to estimate the number of brushstrokes in a van Gogh painting.

ERIC POSTMA: In this one section alone, about 32 strokes.

On Screen Text: And this section?

ERIC POSTMA: 210.

On Screen Text: And the whole painting?

ERIC POSTMA: About 1753.

On Screen Text: Thanks, Eric.

PROFILE: MAYDIANNE ANDRADE

NEIL DeGRASSE TYSON: Nature is full of strange behavior and displays, much of it done in the name of love.

Take the peacock, for example. Look at this thing. How could you walk with all that weighing you down? And it's just to attract a lady friend.

And how about the angler fish? The little male latches onto the female and doesn't let go—ever.

In this episode's profile, we meet a biologist whose subjects engage in some of the weirdest, even gruesome, behavior. She insists it's worthwhile because it passes their genes on to a new generation.

MAYDIANNE ANDRADE: I do really like horror movies, really entertaining to watch horror movies that make spiders into villains. They capture something essential about what it is about spiders that scares so many people: the intelligent, stalking nature of the way that they go after their prey, maybe how fast they can move. Spiders stalk their prey like cats, you know? They're quiet, you would turn around and then suddenly one of them is there.

NEIL DeGRASSE TYSON: Meet Maydianne Andrade, evolutionary biologist at the University of Toronto. Although she loves a good scary movie, Maydianne isn't really afraid of spiders.

In fact, she's the leading expert on the Australian redback, a poisonous spider and close relative to the black widow, with one of the strangest mating behaviors in nature: the tiny male will climb onto the much larger female, and actually offer himself up as a meal.

MAYDIANNE ANDRADE: He will insert in the female, and then he'll flip and basically do a somersault to a position where his body is immediately above her fangs.

NEIL DeGRASSE TYSON: As they mate, the female will begin eating the male, alive.

MAYDIANNE ANDRADE: She'll actually pierce him and begin to chew up parts of his abdomen and eat him while he's mating with her.

NEIL DeGRASSE TYSON: Studying the mating habits of potentially deadly spiders is not for the faint of heart, but there was a time, growing up in British Columbia, when Maydianne herself was a little squeamish.

MAYDIANNE ANDRADE: I remember, in particular, one day when my brothers and I were watching TV, and this little spider sort of crawled across the floor. And we all just lost it. And we put a bowl over top of it, and we decided that I was going to quickly lift up the bowl, and my brothers had the vacuum. And of course, for a joke, the brother who was supposed to turn it on didn't. So, there I was with the bowl up, and the spider's starting to freak out, and it was one of the traumatic moments of my childhood. Things have kind of changed since then.

NEIL DeGRASSE TYSON: So how was a girl who was once terrified of simple house spiders inspired to go on to study these eight-legged creatures?

As a graduate student, she became intrigued by a strange phenomenon found in the insect world, sexual cannibalism.

DARRYL GWYNNE: The classic systems in which everybody from school kids to naturalists often find out about sexual cannibalism are praying mantids and the black widow spider.

NEIL DeGRASSE TYSON: In the case of the praying mantis, the females often eat the males during the mating act.

As her research subject, Maydianne selected the Australian redback, a spider whose females were rumored to possess a big appetite for their mates.

MAYDIANNE ANDRADE: I got some of the spiders in the lab and waited and waited, and nothing ever happened. And then finally I realized, well, you know what, they're nocturnal; they're active at night. So I have to start coming in at night. And again, I waited and waited, and not much happened.

And so one day, I just said, "You know what? I'm staying all night. It's got to be happening somehow." And so finally, at about 2:00 or 3:00 in the morning, after a five to eight hour courtship, I finally saw it. I finally saw this behavior I'd read about and wanted to base my research on.

NEIL DeGRASSE TYSON: What she saw was the male spider literally throwing himself into the jaws of the female as they mated.

MAYDIANNE ANDRADE: I mean, it was amazing. It was, like, a eureka moment, and I went running all over the building. And, of course, no one was there, because it was the middle of the night. And, I finally, I think, found a custodian and, and, you know, told him about it. And you know, he thought it was pretty strange. But still, it was a fantastic moment.

NEIL DeGRASSE TYSON: Now Maydianne's true test would begin. She left her home in Toronto for Australia, where night after night she searched for poisonous spiders.

MAYDIANNE ANDRADE: It was a very solitary, slightly creepy kind of a thing. Sometimes I would harken back to those horror movies, because I would be mesmerized in what I was watching on those webs, and then I'd suddenly realize, "I'm in this area all by myself. It's 2:00 in the morning. It's pitch black. Is that a noise I heard over in the bush?"

NEIL DeGRASSE TYSON: And at all times she had to remember that these spiders were potentially deadly.

MAYDIANNE ANDRADE: The venom goes into your bloodstream and your lymph system, and it causes pain, sweating, muscle contractions, vomiting, diarrhea, fever, chills.

NEIL DeGRASSE TYSON: But the risk would be worth it, if she could answer this evolutionary riddle: why would the male spiders sacrifice themselves? There had to be some benefit for the species.

MAYDIANNE ANDRADE: My fieldwork was aimed at asking about male opportunities for mating in nature. Was it true that males often only got one chance at mating or only encountered one female in their lifetime?

NEIL DeGRASSE TYSON: She meticulously tracked and documented the lives of nearly 2,000 male spiders.

And in the end, the results were astonishing.

MAYDIANNE ANDRADE: Unfortunately for male redbacks, they're fairly small, and once they're off their web, they're actually really vulnerable to all sorts of other animals. So most males are killed, one way or the other, before they reach a female.

NEIL DeGRASSE TYSON: In fact, Maydianne showed that only one in five male redbacks ever got to mate at all. And when they did, their ultimate sacrifice paid off. The male spiders who somersaulted into the jaws of the female during the mating act produced more offspring.

MAYDIANNE ANDRADE: For redbacks, if a female eats the male, she actually lets him mate for longer, and that means he transfers more sperm, and he'll have more babies.

NEIL DeGRASSE TYSON: This explains how the redback spider's bizarre mating behavior evolved.

MAYDIANNE ANDRADE: A male who throws himself into the jaws of death and has a thousand more offspring than his competitors, that trait is going to go on into the next generation. So, the next generation, we're going to have a thousand more males who do the same thing. And presumably, that's what happened in the evolutionary past, in redback spiders.

NEIL DeGRASSE TYSON: She published her discovery, as solo author, in the prestigious journal Science, a rare feat for an established scientist, much less a master's student.

MAYDIANNE ANDRADE: I mean, I almost cried, I was just so floored by the fact that other people thought it was important, too. It was fantastic.

NEIL DeGRASSE TYSON: Maydianne went on to get her Ph.D., and today continues her research on the Australian redback. And she now has a mate of her own, fellow professor and arachnid expert, Andrew Mason.

ANDREW MASON (Maydianne Andrade's Husband): I first met Maydianne at the lab where I was working, doing my Ph.D. I looked up from my work and sort of briefly explained what I was doing, and she asked a question about it, and that was it.

MAYDIANNE ANDRADE: He looked up, and I mean, I could almost say that that was it, from the moment we saw each other. I never used to believe in that stuff, but I do now.

NEIL DeGRASSE TYSON: They even spent their honeymoon hunting for bugs in the Canadian Rockies.

MAYDIANNE ANDRADE: It's worked out better than I could have imagined. Certainly better than my parents would have imagined, when I told them I wanted to study spiders, probably. I'm guessing they were expecting an old maid.

NEIL DeGRASSE TYSON: And together Maydianne and her husband are continuing their work on sexual cannibalism, with the hopes of making further discoveries about the secrets of evolution.

MAYDIANNE ANDRADE: A lot of people will come up to me and say, "Why sexual cannibalism?" Why would I study something so strange for so long? But really, in a way, it's what evolution's all about. It's sex and it's death, and it's all wrapped up into one really interesting story.

On Screen Text:Okay, guys, if it makes you feel any better...there is a species which practices male on female cannibalism, sort of. There are these parasitic isopods that live inside fish; the male eats the female, but there's a twist: he then becomes a female! Pretty crazy, huh?

AUTISM GENES

NEIL DeGRASSE TYSON: The human brain is awesomely complex and difficult to understand, but researchers are now unraveling the secrets of how our brain forms and develops, from the time we're a small embryo, up through adulthood. And that's crucial, because, not only does it help us understand who we are, but it will help us treat and possibly even cure some of the most frustrating diseases, like autism. Correspondent Chad Cohen met the researchers who are finally uncovering clues to what might cause this devastating disease that, up until now, has been a mystery.

CHAD COHEN: This is what most people picture when they think of autism: Dustin Hoffman in the movie Rain Man.

MICHAEL D. ROBERTS (Film clip, Rain Man): Hey man

CHAD COHEN: He's obsessive

DUSTIN HOFFMAN (Film clip, Rain Man): Twenty-seven minutes to Jeopardy, practically 26 minutes to Jeopardy.

I get my boxer shorts at K-Mart in Cincinnati.

TOM CRUISE (Film clip, Rain Man): What did I say, Ray?

CHAD COHEN: He's repetitive

TOM CRUISE (Film clip, Rain Man): What did I tell you Ray? We are not going to Cincinnati and that's final.

DUSTIN HOFFMAN (Film clip, Rain Man): I get my boxer shorts at K-Mart.

TOM CRUISE (Film clip, Rain Man): Raymond, that is final, do you hear me?

CHAD COHEN: He's lost in his own world.

In real life, autism is a devastating disorder that seems to be on the rise. It has a wide spectrum of symptoms and its clues to what causes them are few and far between.

One thing that we do know is that it runs in families. These twins, Myah and Evan, both have it. As do these two brothers Collin and Liam...

This boy, Jeffrey, is autistic, and so is his brother, Zachary.

In fact, when one child in the family has a sibling with autism, the odds that siblings other kids in the family will have it skyrockets from about one-in-150 to one-in-five. This suggests a genetic cause, but so far, autism it's genes have been elusive. now, the biggest hunt ever for autism genes is underway

Now, scientists are embarking on their biggest attempt ever to find those genes, and the search is paying off..

MARK J. DALY (Broad Institute): We were never able to even imagine, five years ago, that we would be able to do the kinds of studies we'd be doing today.

CHAD COHEN: It all began with one family that wouldn't take no for an answer, the family of a small boy named Dov Shestack.

PORTIA IVERSON (Mother of Dov Shestack): When Dov was a baby, he seemed pretty normal. He was making eye contact, he was laughing, he was babbling. He would try to get our attention as we walked by, all those...all the regular little baby things.

CHAD COHEN: But when Dov was about a year old, he stopped responding to his name, stopped making eye contact, and finally, he stopped talking.

His parents, Jon and Portia, were told that Dov had autism and was probably severely retarded. There seemed little hope he would ever get better.

PORTIA IVERSON: I couldn't accept the idea of this death sentence on my very young child.

CHAD COHEN: Portia decided took it upon herself to learn all she could about autism. She studied all sorts of literature on the brain, and started contacting scientists, literally hunting them down.

She went to one of the biggest brain science meetings in the world, held by the Society for Neuroscience, which draws more than 25,000 researchers, among them, a geneticist from Boston named Rudy Tanzi.

RUDOLPH E. TANZI (Massachusetts General Hospital): To be quite honest, when I was first contacted by Jon and Portia, I didn't know anything about autism.

CHAD COHEN: Tanzi was intrigued by the mysterious genetic links in autism.

But early in his career, Tanzi discovered the first genes that cause another complicated brain disease, Alzheimer's.

He did it by analyzing hundreds of D.N.A. samples from families with Alzheimer's victims.

Intrigued by autism's mysterious genetic links,

So he gave Portia and Jon a critical piece of advice.

RUDY TANZI: I told them that, if you want to find genes for a disease, the first thing you need is family material. You need families with autism—lots of them—and D.N.A.

CHAD COHEN: Portia put together a team that traveled all over the country, collecting blood from families with at least two autistic children.

And After a couple of years, she'd built a scientific goldmine.

And here it is: Portia's autism D.N.A. bank. It may not look like much, but these are samples from a thousand families, now tucked away in this rather nondescript looking fridge in Rudy Tanzi's lab.

As the search for genes began, there was another puzzling clue about the way they started the gene hunt began with a rather puzzling clue about autism. Children don't seem to be born with it.

For the first year or so, their brains appear to be developing normally.

TAKAO HENSCH (Harvard Medical School): Most of our brain is formed beautifully by gene programs early in the fetus. And this gives us a brain structure that is similar from one person to the next. The right parts of the brain are wired up appropriately.

CHAD COHEN: The symptoms of autism often don't kick in until after the first year of life, as this is when millions of brain cells, called neurons, connect with each other by sending chemical and electrical signals throughout the brain. For normal brain function, IT these signals have to be sent at exactly the right place and time.

CHARLES A. NELSON (Children's Hospital Boston): One principle of brain development is: timing is everything. Whereas in real estate, it's "location, location, location," in the brain, it's when things happen.

CHAD COHEN: Since it's known that genes control much of brain development, it's possible

So perhaps faulty genes might might be disrupting the process the process development in autistic children.

And those faulty genes might well be hidden somewhere in the new D.N.A. bank.

To find them, Tanzi collaborated with Mark Daly and colleagues at the Broad Institute in Boston, who have developed cutting edge D.N.A. screening programs.

MARK DALY: This, right here, is a gene chip, which performs the ultra-high-resolution D.N.A. fingerprint of each individual.

So you take our family, our genetic samples from our autistic families, and you load them onto this chip.

CHAD COHEN: Each one of these gene chips contains D.N.A. from an autism family and D.N.A. from a family that's disease-free.

Scanners read the D.N.A. sequences—the As, Cs and , Gs and Ts that make up our genes—and are then compared.

Millions of these chemical bases, across the entire human genome, can be analyzed, scanned in a matter of hours. Any difference between the normal D.N.A. and THE D.N.A. from the autism bank could will be an important clue.

And so this comes up and this ultimately gives you... it gives you a list of where there's a match and where there isn't. And, for the most part, you're interested in where there isn't a match.

MARK DALY: In many cases, that's one of the first things we look for.

CHAD COHEN: One place there wasn't a match (or the scientists found a mismatch) is on chromosome 16. where a number of genes controlling brain function happen to be located.

The dip in this red line reveals a section of the chromosome 16 where a big chunk of D.N.A., with at least 25 genes, is missing in some of the autism families.

THE MISSING DNA CONTAINS AT least 25 genes. This deletion is rare but vicious. It increases the risk of autism 100-fold..

That may be because some of the missing genes are critical players in wiring the brain. If these genes are broken, then, perhaps, the circuitry of the brain is broken, as well.

If these genes are Broken, that

Might disrupt the flow of information from synapse to synapse.

(Do we need?)

MARK DALY: You may end up with situations in which you have too much information being transferred, not enough information being transferred. Something may not be working in the critical first period of life, when so much is being learned and so much is developing and changing in the brain.

CHAD COHEN: The team's next discovery was even more interestingNOT RARE AT ALL. . On chromosome number 5, they found a stretch of D.N.A. that's present in all of us, but is altered in some of the autism families.

In the middle of this D.N.A. is a mysterious gene with no known purpose, but its location is a tantalizing hint. It's right next door to a gene called Sema5A.Rudy tanzi showed me where it's located in the human genome.

or recently, the gene chips revealed another key stretch of dna implicated in autism. the gene has no known purpose...but it's location on the human genome offers a tantalizing hint

RUDY TANZI: We look it up, and we see this gene's involved with how nerve cells connect with each other in building your neural circuitry of the brain during development.

CHAD COHEN: The fact that Sema5A is so close to the mystery gene WAS is intriguing. Genes in the same neighborhood can have similar functions.

It's possible that one or both genes could be involved in autism.

And, significantly, the altered stretch of D.N.A. showed up in almost 10 percent of the autism families. That's a large enough number to suggest it could play a real role in the disease and an important step toward understanding autism.. now it's a question of what we can do with

RUDY TANZI: When you know that there's a gene with a defect, you can think two different ways about it. One is that, was the brain not wired correctly in the beginning? And that's the worst case scenario, because it's tougher to fix a circuit that's not built right.

CHAD COHEN: Right.

RUDY TANZI: But these kids function. They can still love. They can still learn. So there's still a lot of optimism that maybe we can go in, and if we figure out what's wrong with the neural circuitry, we can figure out a way to make it work better, so at least improve the lives of these kids, and, you know, if we're really lucky, maybe even exclude most of the disease symptoms. But it's genes that are teaching us how to do that.

CHAD COHEN: Dov Shestack is a remarkable example of how the brain can still function even with severe autism. Dov had never learned to talk, but when he was nine, he was able to start communicating by pointing to letters on an alphabet board. even to those closest to him, it was an amazing revelation.

He was asked what a galaxy is, and to everyone's amazement, he pointed to the letters that spelled out "a group of stars."

PORTIA IVERSEN: He knew how to spell, he knew how to read. He had normal intelligence, which we never could be sure of. One of the first things we asked Dov when he began to communicate was, "What have you been doing all these years?" And he just typed out the word, "listening."

CHAD COHEN: Dov is 17 now. He'll always live with symptoms that make it hard for him to function. But even as he struggles, he goes every week to a bar mitzvah class for autistic children. It's a rite of passage no one ever thought he'd experience.

-- And holds out, for him, his family and everyone else affected by autism, it's a source of hope. and for others, hope for a better future

PORTIA IVERSEN: Hope's a very good thing to have. I think you, kind of, can't live without it. I think that had we not hung onto it then, whether or not people called it false hope or not, we wouldn't be where we are now. So I think hope is a very good thing.

On Screen Text: Take a quick look at this film clip. Yale researchers recorded eye movements of people as they watched it. The viewer's eyes follow to the painting. Then they recorded the eye movements of autistic people watching the same shot. People with autism were unable to read the social cues necessary to find the painting.

The Yale team hopes to use this method as a diagnostic tool for autism.

COSMIC PERSPECTIVE: PLANET HUNTERS

NEIL DeGRASSE TYSON: And now for some final thoughts on the search for planets.

For the longest while, we just assumed that other star systems in the galaxy would look just like ours: a few small, rocky planets near the host star, some larger gas-rich ones farther away, and perhaps a swarm of comets and asteroids to round out the family. Turns out, none of the nearly 300 star systems in our catalogs looks anything like ours. Most have giant gas planets orbiting relatively close to their host star, which would gravitationally disrupt any smaller rocky ones nearby.

Of course the search methods today are more likely to find these kinds of star systems, so we shouldn't jump to conclusions.

Just as your lost car keys could be anywhere in the street, but you are more likely to find them under the lamppost since that's where the most light is, the search continues for rocky planets at the right Goldilocks distance from their host star, where water remains in its liquid phase.

We care about them because we're driven by the search for life as we know it, and by the prospect of finding life as intelligent as we are, but what about the search for life as we don't know it? Just because Earth is good for us, and just because we call ourselves intelligent doesn't require that alien life prefers rocky planets, or would even judge us to be as intelligent, relative to themselves.

Just a call for an open mind on the frontier of cosmic discovery.

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 much more. Find us at pbs.org.

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

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