Jill Tarter: A Scientist Searching For Alien Life

July 23, 2012

Guests: Sam Kean – Jill Tarter

TERRY GROSS, HOST: This is FRESH AIR. I'm Terry Gross. My guest, Sam Kean, has written a new book about what DNA has to tell us about the mysteries of human history and about what our individual genetic makeup reveals about ourselves. The book is called "The Violinist's Thumb: And Other Lost Tales of Love, War and Genius, as Written by Our Genetic Code." 1

The violinist's thumb refers to Paganini's genetic disorder that gave him what Kean describes as freakishly flexible fingers. Kean's previous book, "The Disappearing Spoon," was about the periodic table of the elements. That might sound dry or arcane, but it was a best-seller. His work has been published in the New York Times Magazine, Mental Floss and Slate, and he's been featured on the NPR program "Radio Lab."

Sam Kean, welcome to FRESH AIR. Well, the book starts with you sending in a saliva sample so you can get your genome mapped. Why did you decide to do that? Was that just, like, research for the book?

SAM KEAN: It was research for the book, and I admit I did it on a bit of a lark. I just thought I would find I had an interesting gene or maybe something about my background that I didn't know, and so I sent it off and forgot about it for a couple weeks.

But then I went online and had to register the test, and that's when things got a little hairy for me because they go into and they look for susceptibilities to certain genetic diseases. Most of them I was comfortable looking at and knowing whether I had a susceptibility, but when I saw the one for Parkinson's disease, that is the one that got me.

My grandfather had it, and when I saw that they tested for susceptibility to Parkinson's, I had a very strong visceral reaction to that, and I sort of blacked it out, in that you can go in and prevent yourself from seeing any information about that.

GROSS: So you decided to basically redact the part about your genetic susceptibility to Parkinson's disease, but then later you got a note in the mail saying that you may be more at risk for Parkinson's than was originally stated in the first report that you got back. So explain what that note said and how you responded to it.

KEAN: Sure. Actually, I went in after I'd written the book and I felt like I had really gotten an education about what genetics means. And I felt like I was more prepared to handle the information. So after I finished writing most of the book, I went in, I broke the electronic seal, and I found out that I did not have, according to the information they had, a higher susceptibility.

And this was a big, big relief for me, obviously, that I wasn't facing this. But then later, as you said, I got an email saying they had updated test results for me, and one of those updated ones was for Parkinson's. And I clicked on it, and there was a bit of a switcheroo in that now, suddenly, it seemed like I did have a slightly higher risk for Parkinson's.

And beforehand, I think that really would have gotten me because it's one thing to suspect you might have it and to find out that you do. It's another thing to suspect you might think that you don't have it, kind of feel the relief, and then find out that you do anyway.

But at that point, again, I'd learned enough about genetics and how genes work where I felt comfortable with it, and I really feel like going through the book gave me an education on how genes work and the fact that genes really work with probabilities. They don't work with certainties.

And with most of the things that you're looking at with these genetic tests, it's not like you're condemned to automatically get the disease or to get the syndrome. There's a lot of factors in play there. And so I just felt more comfortable with the information.

GROSS: Well, exactly how predisposed are you? Like what changed from the first report to the second report?

KEAN: It was something like a 20 percent greater risk, and this is for a disease that only affects, you know, a couple percent of people anyway. So it was pretty modest risk. But I think that beforehand, it was just even the idea of Parkinson's, it was just a strong, visceral, emotional reaction to it. And once I educated myself a little bit, I realized that the risk wasn't that great anyway.

GROSS: So you're wondering if by getting your genetic profile, that if you would learn interesting things about your genes or about your background, did you find any, you know, surprises besides the unfortunate Parkinson's slight predisposition surprise?

KEAN: No, a lot of it confirmed things that I already kind of knew about myself, like the fact that I don't deal with caffeine all that well. I get a little jittery, or I have to end up staying up too late.

GROSS: Wait, wait, now what in your genetic profile would confirm that?

KEAN: There are some people who just don't break down caffeine all that well, and so it ends up staying in their system for longer than other people do, and they just know that there are certain genes out there that make proteins that can break it down pretty easily, and other people, they just can't break it down as well.

GROSS: OK, so you have empirical proof that coffee is difficult for you.

(LAUGHTER)

KEAN: Yeah, it was kind of - it was kind of nice to have it spelled out that it wasn't just me kind of making it up or kind of cherry-picking evidence. I could look at it and say OK, no, I probably do have something like that.

GROSS: So let's talk a little bit about what is a gene versus what is DNA.

KEAN: DNA is really a chemical, fundamentally. It's a substance, you know, it sticks to your fingers. It's a thing. A gene is made of DNA, but in some ways, it's better to think about a gene a little more abstractly. The way I mention it in the book is that genes are like the story, and DNA is the language that the story is written in.

Genes are something that scientists have known about for a long time. Gregor Mendel discovered them in the 1860s, and then in the very early 1900s his work was rediscovered and scientists really started digging in to genes. But we didn't know that genes were DNA for a long time after that.

So they are sort of conflated in most people's minds today, but they really are distinct things, and as hard as it is for us to understand it looking back, most scientists thought they were completely separate at the beginning of the 20th century.

GROSS: One of your chapters is framed around a Japanese man who managed to survive the Hiroshima nuclear bomb blast and then fled to Nagasaki, arriving just in time for the second atom bomb, which he also survived. How does his story relate to your book about genes?

KEAN: This man was Tsutomu Yamaguchi. He was in Hiroshima temporarily and as you said had to end up fleeing to Nagasaki, where he was from. And I explain it in terms of DNA because radioactivity, when it attacks your body, what it's really attacking most of the time is your DNA. It creates these things called free radicals inside you, and they go after DNA and end up kind of cutting it into pieces.

They do a lot of damage to DNA, and that's what gives rise to a lot of the problems with radiation exposure, especially things like cancer that come in down the line. And I looked at the story of Yamaguchi because he ended up surviving for an amazingly long time after being close to both nuclear bombs.

He actually lived until the year 2010, 65 years later. He must have had inside his cells a very efficient way to repair DNA and to make sure that any mutations he might have had got patched up. And so I - again, I used him as kind of a frame to explain how mutations come about, and then again how our body fixes mutation, sometimes in really incredible ways.

GROSS: And you write all living organisms have - like they accumulate mutations as they age. Like what?

KEAN: Well, there's a couple ways that this can happen. DNA uses four letters to store information. There's A, there's C, there's G, and there's T. Those are chemicals. But again, they're what DNA uses to store information. Sometimes a mutation will swap one of these letters in for another one, and it will change the protein that ultimately gets produced.

Other times, genes have a definite starting point, and a definite stopping point. It's just like a sentence that has a capital letter at the beginning and punctuation, a period, at the end. Sometimes the period gets erased, and so it turns into basically a run-on sentence and just keeps going and going.

Other times, especially with radioactivity, segments of DNA can actually get cut out completely. I like to think about this as those old gnarled telephone cords that you sometimes see, when they get completely twisted into a ball. If a bit of radioactivity comes streaking through and cuts the DNA at a certain point, some of those coils actually end up getting pulled aside, and your cells will solder the DNA together and leave that coil out completely. So there's a lot of different ways that DNA can get damaged.

GROSS: And is cancer basically the kind of mutation that you're talking about?

KEAN: Yeah, cancer, despite all its various forms and presentations, is really a DNA disease. It comes down to the fact that we have these certain genes that prevent our cells from growing out of control, from proliferating at the expense of the body, and it's a pretty good, pretty robust system.

But if a couple of these genes fail, then that's when cancer starts, and cells start growing out of control. So yes, cancer is very intimately tied to DNA mutations.

GROSS: My guest is Sam Kean, author of the new book "The Violinist's Thumb: And Other Lost Tales of Love, War and Genius, as Written by Our Genetic Code." We'll talk more after a break. This is FRESH AIR.

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GROSS: If you're just joining us, my guest is Sam Kean. He's the author of the new book "The Violinist's Thumb: And Other Lost Tales of Love, War and Genius, as Written by Our Genetic Code." You have several pictures in the book. My favorite is a picture of a newborn baby with a tail. The tail is what is known as an atavism, an evolutionary throwback to, you know, an earlier time in our evolutionary past, like a tail.

Why does this interest you in terms of, you know, your book about the genetic code?

KEAN: Well, the book really tries to take us through human history, from our very earliest hours, and even in our microbial past, all the way to the glories of modern civilization. So yeah, all of us had a tail at one point in our development, and then it kind of gets reabsorbed into the body unless you have a mutation or something that prevents it from getting reabsorbed. And at that point, you can be born with a tail.

They're usually perfectly harmless, these tails, and this was of course one step along the way. We used to be, you know, monkeys, basically. Human beings share a common ancestor with apes and monkeys, and at some point in our past, we did have a tail.

And it was just interesting to me that in some cases, we have the genetic blueprints to make these atavistic traits inside us like tails. Another famous example is human embryos. You can start to see our gill slits. And that, of course, is even way farther back in our past than tails.

So it's just interesting to me that we have these remnants of traits inside us that never quite got pruned out. We don't really use the DNA for much anymore, but every once in a while it can pop up.

GROSS: When the fetus is being developed, does it ever have a tail?

KEAN: Oh, yes. The fetus actually does have a tail up until about 16 weeks or so.

GROSS: What are some of the other atavisms that you found in your research?

KEAN: Gill slits was another one. We also have - this is more of a controversial one. We also have the remnants of what's called the vomeronasal organ. It's basically a second kind of nose inside us. A lot of mammals have this. Mice, for instance, depend very heavily on their sense of smell, and so they have this organ inside us.

And humans have some sort of remnant of it, but no one quite knows if it works yet. There's a lot of scientists who don't think it does, but then there are other scientists who say, no, they think it does do a little bit of something. And its basic job in most mammals is to detect pheromones. You know, we hear about pheromones sometimes in the news, or there are products that claim that they have pheromones added to them to make you more attractive to the opposite sex, things like that.

But this pheromone detector, we have a trace of it inside us. So that's another good example of a genetic atavism.

GROSS: In your book "The Violinist's Thumb," you write about cannibalism, which I didn't expect to see a chapter about, and why cannibalism is not only, you know, a kind of, you know, abhorrent action, but it's also unhealthy.

KEAN: Yeah. There are certain diseases, prion diseases, they are called, that you can get from eating other human beings, specifically if you eat their brains. These prions can get inside you and they can attack your own brain. And if people remember the mad cow scare from the mid-1990s; that was another example of a prion disease.

But there is some indication in our DNA that perhaps cannibalism was a lot more common in our past than we might like to think about. There are certain genetic signatures that protect us against prion diseases, and these signatures are pretty widespread among human beings worldwide, and for them to get that widespread, you know, it's possible that we would have had to indulge in a lot of cannibalism.

This is another controversial theory, but there's a lot of scientists who think that it's good evidence for widespread cannibalism.

GROSS: One of the pictures in your book is about Dolly, the sheep that was cloned. It's like the first cloned animal. What do you think the odds are, as someone who's not really an expert on calling the odds on this, but what do you think the odds are of a human being being cloned one day?

KEAN: Human beings are actually tougher to clone than other animals are for a few reasons. And actually it's not just human beings, it's primates, generally. We have this apparatus inside our cells that holds part of the nucleus in place. And when they try to take the nucleus out - which is a step during the cloning process - when they try to remove the nucleus, it ends up kind of tearing some things.

So human beings actually are tougher to clone than most other animals are. So that's one of the big technical limitations, and I'm not sure we know how to overcome that yet. If we could overcome that, then I think it would be feasible to clone a human being. But as I explained in the book, I'm not sure that there would be a lot of demand for cloning a human being simply because, again, your genes don't determine who you are.

So if you cloned someone, you might get someone who looks sort of like the person, or a lot like the person, but it would be a different person. The world we live in now is much different than the world was 30 years ago. People will have different memories. They will just be a different person. They would probably be less alike than most identical twins were. So even if we could clone human beings, I'm not sure there would be a lot of demand for it.

GROSS: So now that you have a map of your human genome, to what extent do you feel like your script has already been written, you're predisposed to certain characteristics or, you know, possibly an illness, and, you know, part of your script was written when you were born?

KEAN: The more I got into studying genes and human DNA, the more I realized that genes really deal in probabilities. They don't deal in certainties. And that wasn't something that I really understood before. The usual dichotomy is between nature or nurture, and the more we look into DNA, the more we're realizing it's really nature and nurture. It's how genes and your environment work together to produce the person you are.

And so I don't feel like I'm really hemmed in because of my DNA. Obviously, there's some things that were probably never going to happen for me; I was never going to play in the NBA or something like that because of, you know, I'm not tall enough, I'm not bulky enough. Things like that.

But even though we're finding a lot of even behavioral traits that have some sort of genetic influence or roots in DNA somehow. We're also finding that those things don't rigidly dictate who we are. Genetic determinism is an idea that really scares people, and understandably so. But thankfully, the more we find out about our DNA, the more we realize that we're not determined by our DNA; that who we interact with, our environments, things like that, it works with us to make us who we are.

GROSS: Well, I want to thank you so much for talking with us.

KEAN: Well, thank you for having me.

GROSS: Sam Kean is the author of the new book "The Violinist's Thumb: And Other Lost Tales of Love, War and Genius, as Written by Our Genetic Code." You can read an excerpt on our website, freshair.npr.org. I'm Terry Gross, and this is FRESH AIR.

TERRY GROSS, HOST: This is FRESH AIR. I'm Terry Gross. If we're ever contacted by beings from another planet, our guest Jill Tarter may be one of the first people to know. Tarter is an accomplished scientist who spent much of her career looking for signs of extraterrestrial life. Earlier this year, Tarter stepped down from her position as director of research for the SETI Institute. SETI, that's S-E-T-I, stands for Search for Extraterrestrial Intelligence. The organization primarily scans and analyzes radio signals from space captured by powerful telescopes. The idea is that scientists can distinguish a signal that comes from an intelligent source. Though she hasn't found E.T. yet, Tarter isn't discouraged. She'll now work on raising funds to support SETI research.

Jill Tarter has a physics degree from Cornell and a PhD in astronomy from the University of California-Berkeley. She's won a number of scientific awards, including two (unintelligible) service medals. Her work was an inspiration for the Carl Sagan novel "Contact." The film adaptation starred Jodie Foster, who visited Tarter to prepare for her role.

Tarter spoke with FRESH AIR contributor Dave Davies.

DAVE DAVIES, HOST:

Well, Jill Tarter, welcome to FRESH AIR. When you were studying, when you were an engineer, did you think much about the prospects for extraterrestrial life at all? Were you interested in the subject?

JILL TARTER: Not as an undergraduate. Early in my life I had spent a lot of time with my father who had studied astronomy as well as being a professional football player. And we'd walk along the beaches of the west coast of Florida, very dark skies, look up and the beautiful stars, and I assumed at that time that along some beach on some planet around one of those stars, there would be a small creature walking with her or its dad and they would see our sun in their sky, and they might wonder whether anyone was there.

DAVIES: So...

TARTER: But I never thought about it professionally until graduate school.

DAVIES: So what got you seriously interested in this subject?

TARTER: Actually, an accident. When I started in graduate school I learned how to program a PDP-8/S computer. That was the first time that scientists had any real computing power on our desktops. It was wonderful and it was stupid. I mean it had no language, you had to program it, noctal(ph), had to set all the ones and zeroes. But it was a marvelous device. Many years later, it was given as a piece of surplus equipment to an X-ray astronomer, Stu Bowyer, who had a great idea about the possibility of piggybacking on the normal radio astronomy observing that was going on at Hat Creek Radio Observatory that was run by University of California-Berkeley. And so Stu talked to Jack Welch, who is now my husband, about doing a SETI project and Jack said sounds cool to him. Stu didn't have any money so he went begging equipment. One of the pieces of equipment was this PDP-8/S desk and somebody told Stu that I was used to work on that machine. He came to my office, gave me something called the Cyclops Report, an engineering design study done by NASA Ames about searching for extraterrestrial intelligence.

I read that engineering study cover to cover. It was phenomenal. I realized that after millennia of people asking priests, philosophers, whoever they thought was wise, what we should believe about whether or not we're alone in the universe, could now be superseded by doing an experiment, by doing a scientific exploration using the tools of the astronomers. And here I was in exactly the right place with the right skill sets, at the right time, and I got hooked.

DAVIES: And this was what, back in the '70s?

TARTER: It was in the mid-'70s. Yes.

DAVIES: When you search for extraterrestrial intelligence, what do you do? It involves radio telescopes, right?

TARTER: Well, the search for extraterrestrial intelligence is actually a misnomer. We don't know how to identify intelligence over interstellar distances. What we do instead is use technology as a proxy. And we say, can we look or listen in any way that could detect technologies that someone else might be using and that might be modifying their environment in ways that are detectable over interstellar distances?

And pragmatically, to date, that means we're using radio telescopes to listen for signals that are generated either for their own purposes - and we just eavesdrop on the leakage - or they're beacons, intended to attract the attention of us - an emerging, young technology in the galaxy. And at optical wavelengths, instead of looking for signals that occupy only one narrow range of frequency - which is what we do in the radio - in the optical, we look for signals that are broadband - flashes of light - that last for a billionth of a second or less. And we're constantly thinking about what's the next new technology that we might innovate which in turn could be a better way of looking for extraterrestrial technologies. We do reserve the right to get smarter and we certainly don't think that we know all there is to know.

DAVIES: Now you said in the optical (unintelligible) you're looking for bright flashes that last a billionth of a second? Why?

TARTER: Or less, because that's what a laser can do. Mother Nature does not seem to be able to do that extreme time compression to produce a bright signal in a very short period of time. But lasers can do it, no problem. And if you take lasers and you focus them with big mirrors you can get enormously bright signals that, for that billionth of a second, outshine the stars.

DAVIES: OK. And radio astronomy, why is there so much radio astronomy? And how does the search for extraterrestrial intelligence use that technology to look for signals of interest?

TARTER: Well, radio astronomy, optical astronomy, X-ray astronomy, gamma ray astronomy - they're all studying light, but light at different wavelengths. So each part of the electromagnetic spectrum allows us to learn something different about the universe and about its physical properties. So radio wavelengths are just long, tired light. If you're looking for signals that have persistence, that the radio part of the spectrum and looking for signals that occupy only one channel on the radio dial, our good guess is for something that's obviously engineered, and at the optical end of the spectrum that the right flashes that last only a billionth of a second, not capable in terms of Mother Nature. These are the artifacts we're looking for now. So we are hopeful that if we're looking for the right thing - the radio signals and the bright optical flashes - that within a few decades we will have either succeeded or done a significantly large search of our portion of the galaxy that any negative results would in fact be significant.

DAVIES: We're speaking with Jill Tarter. She recently retired from her post as director of the Center for SETI Research. SETI is the Search for Extraterrestrial Intelligence.

We'll talk more after a break. This is FRESH AIR.

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DAVIES: If you're just joining us, we're speaking with Jill Tarter. She spent much of her career in the search for extraterrestrial intelligence and she has recently stepped down from her position as the director of the Center for SETI Research. She will continue to work on fundraising for the effort.

Over the years, you and those of you involved in this have been looking at radio transmissions. How do you distinguish a radio signal from I guess what you would call a normal astrophysical object? How would you distinguish that from something that might come from an intelligent source?

TARTER: Well, early on in my SETI days, that's precisely what I did. I went and used radio telescopes and we looked at the kinds of objects that we knew about and we looked at what the emission from these objects was like. And it became very clear that nature was incapable of compressing a great deal of emission into only a very narrow range of radio frequencies. Nature tends to create sources of radio emission that fill the channel, that are broadband. And so we studied the narrowest features that we could find in the radio spectrum - those were in saturated OH masers and therefore, we said well, that's our sandbox. For technical reasons, for reasons of economy, our technology produces very strong signals with a high signal-to-noise ratio that are very narrow band. We can do it with technology but nature does not seem to be able to do that, which is the primary reason we started looking for that particular artifact.

DAVIES: And presumably, if you do detect this signal from a distant and civilization or a distant life form, it's a signal that originated a long time ago, right?

TARTER: Within our galaxy it could have originated as much as 100,000 years ago, and coming across the galaxy would take that long. That's right.

DAVIES: OK.

TARTER: So we don't know that they're still there but the chances are very good that they are there. We're a young technology. OK, we're 100 years old in a galaxy that's 10 billion years old. Our star is five billion years old and most of the stars in our neighborhood are a billion years older than our sun. We're looking for advanced technologies because anyone less primitive than us isn't detectable. And advanced technology will be older, if they can get old, and send such messages, they can probably continue to survive. So actually that's one of the great things about SETI.

Starting a new train of thought here, but Phil Morrison, one of the co-authors on that 1959 nature paper on SETI, used to call SETI the archaeology of the future. It's archaeology because the speed of light is finite and it's taken the signal a long time to get here. So if there's information there we learn about their past. But if we detect a signal, even if there's no information, even if it's just a cosmic dial tone, we learn that it's possible for us to have a future, a long future. That's because we couldn't possibly be successful with SETI unless technologies on average survive for a long time so that they can be lined up not only in three-dimensional space, close enough for us to find them, but in the fourth dimension in time, so that they are transmitting as we are emerging. I think that is one of the most hopeful things about SETI, this archaeology of our future.

DAVIES: So if we were to find a signal, I mean you might learn more about it with study but it's not like you're going to get a real-time conversation with that civilization going.

TARTER: I think that interstellar communication is much more like the really fruitful communication we have with the ancient Greeks and Romans and Shakespeare, right? There's an enormous amount of information that's propagated forward in time and we learn from it by reading it, even though we can't ask Shakespeare what he thinks about the current election.

DAVIES: There must have been some times, as you've reviewed, you know, this radio signals that you thought you were onto something. You want to tell us one of those?

TARTER: Yeah, I've actually had a couple of those and they're amazing, adrenaline moments. Early on in France, in Nozay, I stayed awake for three days till we actually proved the signal was a distant airport rather than something we were interested in because I thought my French colleague was going to call up Le Monde and tell them we'd found it. And another instance, I was at Green Bank, West Virginia, and we had a second telescope in Woodberry, Georgia, that helped us discriminate against our own technology. Unfortunately, this telescope got hit by lighting and we had three days to observe without it. And during that time, of course, we got a signal that was really interesting and we followed it for almost a whole day before we convinced ourselves that indeed, it was not coming from the star we had been tracking. It was a signal coming in the sidelobes of the telescope. A telescope has peripheral vision just like your eye and this was the SOHO spacecraft, which was in a small sidelobe of the telescope all day long because SOHO was orbiting the sun and so was the planet Earth.

DAVIES: You know, when someone looks at you and says, you know, you've been at this for decades and we haven't found any discernible, clearly discernible signs of extraterrestrial life. What's...

at you and says, you know, you've been at this for decades and we haven't found any discernible - clear discernible signs of extraterrestrial life. What's the argument that you give them that there's a real possibility that there's something out there?

TARTER: The argument's easy. We've hardly begun to search. The space that we're looking through is nine dimensional. If you build a numerical model, the amount of searching that we've done in 50 years is equivalent to scooping one eight ounce glass out of the Earth's oceans, looking and seeing did you catch a fish. No? No fish in that glass? Well, I don't think you're going to conclude that there are no fish in the ocean. You just haven't searched very well yet. And that's where we are.

DAVIES: But those who say, look, what happened on Earth is such a remarkable accident, that, you know, in the primordial mass there were amino acids and then there was these billion years of evolution that made us who we are, that's just not going to be replicated out there. What gives you some reason to believe that it might be?

TARTER: Well, I would argue that we're intimately connected with the cosmos. We are, in fact, made out of stardust. The iron in the hemoglobin molecules in the blood in your right hand came from a star that blew up eight billion years ago. The iron in your left hand came from another star. We are the laws of chemistry and physics as they have played out here on Earth and we are now learning that planets are as common as stars.

Most stars, it appears now, will have planets. There are all kinds of different planets and not every one is going to be like ours. Nor necessarily does it have to be. We have been studying extremophiles that live in incredible conditions, a range of conditions here on Earth, so the habitable real estate out there is getting larger.

DAVIES: When you say extremophiles, you're talking about life forms here on Earth that live in extraordinary conditions, right?

TARTER: I am. I'm talking about life forms.

DAVIES: Such as?

TARTER: We have microbial life that lives in the boiling battery acids of Grand Prismatic Springs in Yellowstone. We have life that lives two miles beneath the surface of the Earth. There's more biomass under your feet in the surface of the Earth than there is on the surface and above.

There's life at black smokers, the bottom of the ocean where the crust is splitting apart, huge temperatures and high densities and no sunlight and a beautiful collection of tube worms and blind shrimp and all kinds of wonderful life.

DAVIES: And are these life forms that have a different evolutionary origin from ours? Or are we all branches of the same tree here on Earth?

TARTER: We are related to those life forms. We share a common ancestor with those life forms and evolution has taken them in directions that allows them to exploit these various niches. We think boiling battery acid is really uncomfortable. They're perfectly evolved to make a living there.

DAVIES: As people contemplate the notion of contact with extraterrestrial civilizations, what do you say to those who say, hey, we don't want to let people know we're here? They might come and, you know, wage war on us, enslave us, exploit us for our natural resources.

TARTER: Right. Stephen Hawking has warned that we shouldn't be transmitting because it didn't work out so nice for the natives when Columbus showed up. Well, that horse is already out of the barn. We've been leaking radiation for about 100 years. So there is information about the technology on this planet that's now 100 light years away from Earth and there are many thousands of stars in that vicinity.

So the question is should we deliberately transmit to try and attract attention? I don't think that we should purposefully - for now. We're the youngest kids on the block. We just barely have enough technology to begin to dabble in this exploration. Let the older civilizations do the harder job of transmitting.

DAVIES: Aren't we transmitting anyway? I mean, we're putting HBO out there, right? I mean...

TARTER: Well, we are certainly leaking. That tends to have lower power than we would be able to put into a deliberate transmission. So the leakage is harder to find than deliberate transmissions. I think we should listen first and transmit when we get older. And I don't worry about the consequences. If they can get here, they are technologically far in advance of the 21st century Earth.

They are an old technology. How did they get to be an old technology? Well, one thing, one way might have been that they outgrew the aggressive tendencies that were probably at the base of their becoming intelligent in the first place. When you look at evolutionary biology, at least on this planet, one explanation for how intelligence arose is the predator/prey situation that ratchets up intelligence.

But after a while, when the kill power becomes so extreme, then in fact our evolutionary best strategy might be to back away from that. Steven Pinker has a recent book that argues that we are kinder today than we used to be. So I don't think you can get to be an old technology unless you manage to stabilize your population, husband your resources, and get your world in shape.

And if you've done that, then what we offer them is information, is uniqueness. I think they, if they were to come here, would be interested in exactly what the laws of physics and chemistry did here as opposed to what it did where they came from.

DAVIES: They'd be here to explore, not conquer.

TARTER: I think so. If they can get here, they probably can take care of all of the needs that they have on their own. And the only real source that makes it worthwhile to travel is information. What's different here than was back there?

DAVIES: We're speaking with Jill Tarter. She recently retired from her post as director of the Center for SETI Research. SETI is the Search for Extraterrestrial Intelligence. We'll talk more after a break. This is FRESH AIR.

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DAVIES: We're speaking with Jill Tarter. She recently stepped down from her post as director of the Center for SETI Research. That's Search for Extraterrestrial Intelligence. You know a lot of people at NASA. You have, you know, long standing ties to astronomers and others in the scientific community. How do you think they regard SETI?

TARTER: Well, I don't have to actually think to answer that question because every 10 years astronomers and astrophysicists do a self-evaluation, a decadal review. And since the very first one back in the '60s, SETI has been something that the astronomers have chosen to say it shouldn't be a huge project but it is certainly worthwhile to invest a small amount of funding because of the huge potential payoff.

This is essentially getting the Good Housekeeping seal of approval from the National Academy of Sciences when you have a decadal review that recommends that your project be pursued.

DAVIES: Your work inspired the Carl Sagan book "Contact" and then the film with Jodie Foster. Do you have a favorite scene?

TARTER: I have - no. I have a least favorite scene.

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TARTER: There is a problem. I left Arecibo a day before a scene was filmed and it turns out it's a huge innumeracy in the film. Innumeracy is to numbers what illiteracy is to writing. Right? And Jodie Foster is - it's just before the first kiss so she's out on the balcony behind the control room at Arecibo and they're looking at the stars in the beautiful telescope.

And she's doing, oh, look at all those stars. If only one in a million of those stars had planets and if only one in a million of those planets had life and if only one in a million of those life forms were transmitting, there would be millions of signals for us to detect. Well, the math's all wrong. It's really annoying.

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TARTER: There are 10 to the 11 a hundred billion stars in the Milky Way galaxy and even if she was looking up and seeing them all, which she wasn't, because your eye only sees a few thousand stars, but let's say she's seeing them all. She's multiplying 10 to the 11 by 10 minus 18 and coming up with 10 to the sixth. That's wrong by 13 orders of magnitude.

And the really sad story is that Carl Sagan died while his movie was being edited. There was a memorial service for Carl at JPL in the spring after he died in December. And Ann Druyan wanted to show the assembled engineers and scientists a clip from the film, but since it was still being edited, Warner Brothers didn't want to give her a clip that might not end up in the film.

But here, this is just before the first kiss so this is setting up the romantic piece in the film and they know they're not going to lose this. So this is the clip that Annie shows. And you kind of hear this, oh, gasp at the end from all the scientists and engineers who can obviously do the math and know it's wrong. And we tried to get it changed but you can't loop it. It's too close up on her face. And that was sad.

DAVIES: OK. So what should the script have read?

TARTER: Well, you'd be much closer if you said one in a thousand. And then you would have been OK.

DAVIES: OK. So the fact that she ends up in this kind of pod and has this amazing contact with this other civilization and someone appears in the representation of her father, that didn't bother you, but the innumeracy got to you, huh?

TARTER: No. I'm ready to go. If I could have that experience, I'm good to go. Right? Let's do it. I'd go in a heartbeat. But, yeah, you're not going to get there unless you get the math right.

DAVIES: Well, Jill Tarter, thanks so much for speaking with us.

TARTER: Dave, it's been my pleasure. Thanks for having me.

GROSS: Jill Tarter spoke with FRESH AIR contributor Dave Davies. Tarter is the former director of research at the SETI Institute. She retired earlier this year and is now raising money to support the organization.

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