美国国家公共电台 NPR We're All Gonna Live Forever! The Stories We Tell About Conquering Death（在线收听）

SHANKAR VEDANTAM, HOST:

From NPR, this is HIDDEN BRAIN. I'm Shankar Vedantam. The first emperor of China was used to getting his way. By the time he was 40, Qin Shi Huangdi was the most powerful man in the world. During his reign some 2,000 years ago, he united the warring nations of his kingdom. He standardized currency, and weights and measures. He unified border walls into a single block that would eventually become the Great Wall of China. And so it seemed to this man, who was larger than life, who had achieved so many things, that he could also conquer something no one had conquered before - death.

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VEDANTAM: He went searching for an elixir that would give him eternal life.

STEPHEN CAVE: He traveled his kingdom, talking to wizards and alchemists and wise people and priests. And one day, in some distant part of his kingdom, he found a wise man who said, I know the recipe for an elixir.

VEDANTAM: This is philosopher Stephen Cave. He says the wise man was a wizard named Xu Fu, and Xu Fu's offer to get the elixir came with a few conditions.

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CAVE: You just have to get it from this distant island. And if you give me a ship fully equipped and loaded with virgins, I will be able to go to this island and get the elixir of life for you.

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VEDANTAM: The emperor was ecstatic. He gave Xu Fu the ship, the provisions and the virgins. And then he carried on ruling over his great empire.

CAVE: And when he came back to the wizard a few years later, he found out that the virgins were no longer virginal, that the provisions had all gone. And he wondered where this elixir was. And the wizard said, ah, well, I tried to find this elixir, but the closer we got to the island, the more sea monsters rose up. And defeated us.

VEDANTAM: (Laughter).

CAVE: And so if you can only give us more virgins, more provisions and a squadron of archers, well, I'll be able to get it for you.

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VEDANTAM: You might be able to guess what happened. The emperor gave him what he wanted, and off Xu Fu went, never to return to China.

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CAVE: But what's a little interesting twist in this story is that around the same time, there was a legend in Japan about a man who came from China with a boatload of provisions and soldiers. I'm not sure if they mentioned the virgins. And he brought with him a great number of technologies, like agriculture and martial arts and building and many other things, and that became the foundation of Japanese civilization.

VEDANTAM: This story tells us two things. One, humans have been trying to cheat death for thousands of years. And two, the hunger for immortality is inextricably linked to human culture.

CAVE: Almost everything we think of - these technologies of civilization, like agriculture and martial arts and building and clothing and so forth - are, if you like, life-extension technologies. And so I think it's unsurprising that at the heart of the promise, the founding promise of civilization, we find the promise of immortality.

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VEDANTAM: This promise of immortality is a human response to a terrifying idea, the fact that one day we will die.

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VEDANTAM: Last week we spoke with psychologist Sheldon Solomon about this fear and how it shapes our actions, often without us being aware of it. This week we pivot from psychology and politics to religion and history as we explore the many ways people have tried to resolve their fears.

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VEDANTAM: The path to eternal life, today on HIDDEN BRAIN.

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VEDANTAM: Stephen Cave is the author of "Immortality: The Quest To Live Forever And How It Drives Civilization." Much of the book revolves around a philosophical conundrum that Stephen calls the mortality paradox. We know we will die but can't really imagine being dead.

CAVE: It's impossible to imagine not existing. So if you think of trying to imagine being dead, you might imagine being in some other place. You might imagine looking down on your own funeral. But even just being in a void - all of these imaginings conjure a kind of observing eye. You're somehow still there as the observer. So imagining death becomes impossible. And that makes it very, very hard to truly believe that we will completely cease to exist. We are, if you like, innately prone to believe in our own immortality. And this, therefore, gives us our paradox. On the one hand, these enormous brains of ours tell us that mortality, that death, is inevitable. But at the same time, when we try to imagine being dead, we find it's impossible and our brains reject it.

VEDANTAM: You argue in the book that we find four distinct ways and have found these four distinct ways throughout human history to resolve this mortality paradox. You say we come up with these immortality narratives, four techniques that have been used in some ways to sort of bridge the divide of this paradox. I want to talk about them one by one, look at some historical examples of how each of these narratives has been employed, how they're employed in contemporary times, but also some of the potential problems with each of these mortality narratives. Tell me about - tell me about the first one.

CAVE: That's right, that, of course, the fear of death and the realization of death is universal. You find it in all human cultures. And in all human cultures, we find these stories and these strivings, these imaginings, for how we can overcome death or avoid death. And even though there appears to be an enormous diversity of views, I think they actually fit into four basic broad categories. And the first of them, the most obvious, says, all right, we know life as this body, as this sort of human organism on this world. The easiest and best way to stay alive forever is just not to die in the first place. So the simplest form of immortality belief is really to just keep going forever.

Now, on the one hand, this might sound very implausible when we look at the extent to which death and disease and aging are part of everyday reality. Yet at the same time, almost every culture in human history has some kind of story of an elixir of life, or a fountain of youth or something that can enable us to just keep going in these bodies, in this world, forever.

VEDANTAM: So these ideas have been explored at length in popular culture and movies. In the 1992 movie "Death Becomes Her," Meryl Streep plays a self-absorbed actress who wants to stay young and beautiful. So she visits a mysterious woman, played by Isabella Rossellini, who offers her a glowing purple liquid.

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MERYL STREEP: (As Madeline) What is that?

ISABELLA ROSSELLINI: (As Lisle) A tonic.

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ROSSELLINI: (As Lisle) A potion.

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STREEP: (As Madeline) What does it do?

ROSSELLINI: (As Lisle) It stops the aging process dead in its tracks and forces it into retreat. Drink that potion, and you'll never grow even one day older. Don't drink it, and continue to watch yourself rot.

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STREEP: (As Madeline) How much is it?

VEDANTAM: What I love about this clip, Stephen, is how the story, the search for magic potions, it just comes back over and over again in different forms.

CAVE: Exactly. We want so desperately to believe the story. We find exactly this story in the very oldest story known to humankind, "The Epic Of Gilgamesh," which is really the story of a man who realizes when his friend dies that he himself is mortal and then goes on a great quest to find the solution. And at one point, he finds a kind of elixir, but he puts it down beside him to bathe in a pond. And while he's bathing, a snake steals it. And the snake immediately sheds its skin and slithers off. 'Cause the snake, therefore, rejuvenates in the way that we wish we could.

And it's so tempting to think that we are the pinnacle of civilization, and we are the ones who are enjoying all the fruits of science and technology and therefore we are the generation who are really going to crack it. The potion's really - you know, we want to we read in the newspapers, and we suck up those headlines that say, you know, aging defeated, just eat blueberries and put this cream on your face.

VEDANTAM: (Laughter).

CAVE: And of course, you know, a few decades later, as our skin starts to wrinkle and crumple, we realize it was all just wishful thinking.

VEDANTAM: Now, something extraordinary did happen in the course of the last hundred years for really, perhaps, the first time in human history. You know, the length of human lifespan in many parts of the world doubled. Vaccines, sanitations, antibiotics - all of these drove an increase in human longevity. And it really must have felt to many people that we had found a way to cheat death.

CAVE: I think that's exactly right. In a way, we don't celebrate enough this extraordinary revolution that is the doubling of life expectancy in the last couple of hundred years in developed countries from around 40 or so to the 80 years that many people in developed countries can enjoy today now. Now, this revolution, this doubling of life expectancy, does lead some optimists to say, well, if we've doubled it once then we can double it again and again and again, indefinitely. But of course, when life expectancy was doubled the first time, we did it mostly by saving the lives of babies. So many of the interventions you mentioned, such as antibiotics and vaccinations and so forth, were about reducing child mortality.

And, of course, if you get people - if you get a baby through its first few years of life, get a child through its first five years of life, then nature is on your side. And you have someone who is likely - again with a bit of medical support - going to live for 70 or 80 years. Now, of course, taking someone who's 70 or 80 and getting them to live for another 70 or 80 years - as would be required by doubling life expectancy again - is a completely different kind of challenge. And nature isn't on our side at all.

VEDANTAM: So if endless rejuvenation is not a solution, that brings us to the second of your immortality narratives. What is it?

CAVE: So the second immortality narrative I call resurrection. And it's the second one in our logical sequence because it stays with the idea that we are these physical bodies, these physical organisms. And it says - OK, it looks like death is inevitable. Or, I mean, after all, the one thing that all these elixir seekers in the last few thousand years have in common is that they're all now six foot under, pushing up daisies. So if we're not going to find an elixir, we need a plan B. Staying with the idea that we are bodies, we might think, OK, these bodies do have to die, but maybe they can rise and live again.

And this is something we see all around us in nature. We see cycles of birth and death and then rebirth. And a lot of rituals in ancient religions are about taking the very linear progression of a human life from birth through growing and then aging and dying and transforming it into something more like this cyclical pattern of birth and death and rebirth - reappearing one day like the blue birds do in spring.

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VEDANTAM: So what I like about this is that it has such an intuitive appeal. Anyone who has a garden looks out and sees that, you know, plants and shrubs that basically die out in the winter come back in the spring. And it's so easy in some ways to make the intuitive leap that this must be possible for us to do as human beings as well. And the most famous example of this is the resurrection of Jesus. It's the story that's at the heart of Christianity.

CAVE: That's right. In the milieu in which the Jesus story emerged - obviously 2,000 years ago - there were many legends of gods who went down to the underworld - or heroes or kings who went down to the underworld and after some time there, somehow managed to reemerge, to be reborn. And these cults of rebirth were very closely associated with the seasons and with agriculture and were celebrated in spring and so forth. So it does seem deeply embedded in our psyche - the idea that there's a rhythm of rebirth that we can tap into.

And, of course, that's what the Jesus story does in a very explicit way. It builds on older Jewish stories of the promise of the resurrection, of bones rising from the earth. The version of the Jesus story that became so popular in the Roman Empire, and that we've inherited today, is that Jesus died and was resurrected. He physically, as a human organism, rose from the grave. He ate fried fish in front of his followers to prove that he really was a living organism again. And the promise is that if we follow Jesus, that we too can rise physically from the grave and live again. It's a very explicit promise of immortality, which is enormously reassuring.

And we find something like it in nearly all of the world religions - a very explicit promise of immortality can be found in Islam, for example, certainly forms of Judaism, including Orthodox if you like Rabbinic Judaism. And we find something similar in Hinduism and Buddhism. So it seems a crucial part of the success story for a religion - that it promises the defeat of death in some way.

VEDANTAM: Well, one of the things that you mentioned in the book, of course, is that these narratives surface over and over again. In our modern times, we also have a resurrection narrative. It doesn't involve Jesus rising from the dead. It involves science.

CAVE: That's right. Instead of the idea that an omnipotent god is going to raise us up from the grave, nowadays many people are much more inclined to believe in the omnipotence of science and technology. And so we see stories that very much parallel the older stories of resurrection being told in biomedical terms.

So think of cryonics, for example. We all know that freezing things preserves them. Well, maybe we can preserve people when they die or are near death so well that one day, we can thaw them out and repair whatever damage was done to them, whatever it was that was killing them. And we have people who are subscribing to cryonics institutes, paying their life insurance all their lives so they can be put in a big silver pot, when they die, in liquid nitrogen in the hope that one day benevolent and omnipotent scientists will thaw them out and fix them.

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VEDANTAM: Like the rejuvenation narrative, the resurrection story has some serious philosophical holes. For one thing, which version of you is the one that gets revived? Is it the young you, or the old and frail you?

CAVE: Now, imagine that I'm dying and I'm riddled with cancer and very old and falling apart. And God or scientists resurrect me. They somehow pump life back into me. I climb out of the grave and I immediately fall back into it because I'm old and withered and full of cancer. Well, clearly, no one wants to be resurrected as they were just as they died because they would necessarily just die again. So we have to be transformed in some way. They want to be rejuvenated and made immune to aging and disease. And usually there's a great, long wish list of ways in which they'd like to change.

And we see this in Christianity. So Paul talks about being transformed into something immortal and durable, leaving behind all this sort of messy biological stuff. But if I'm to be transformed into something completely different that isn't messy biology, that isn't whatever - 80 years old and full of cancer - what is it that makes that new thing me? It sounds like I've been so completely transformed that I have become - if you like - something else. And this is a deep problem with any notion of resurrection.

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VEDANTAM: When we come back - if rejuvenation and resurrection don't work, where do we turn next?

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VEDANTAM: Stephen Cave is a philosopher at the University of Cambridge. He's the author of "Immortality." He says that as the rejuvenation and resurrection theories run into problems, another story emerges.

CAVE: It says, well, maybe I'm not just this physical body that ages and gets diseased and dies and rots. Maybe there's some other kind of part of me that's immaterial and that doesn't rot. And so this bit of me can maybe survive my biological death.

And we see in Christianity, for example, the resurrection story is now bolstered by this idea that there is a soul. And the soul continues to exist to kind of keep the real me going while the body is in this abyss of death. And when the resurrection comes, soul and body are reunited and so the person is whole again.

But, of course, many people are happy to dispense entirely with the messy, failing, aging, wrinkly body and say, no, the soul is all you need. The soul is the real me. And as long as that continues, then immortality is mine.

VEDANTAM: Now, you write in the book that 71% of Americans believe they have a soul. Among Brits and Germans, it's closer to 60%. In India, it's over 90%. In Nigeria, it's close to 100%. In other words, most of the world's 7 billion inhabitants believe they possess something that is besides and outside of their body.

CAVE: Yes, and I think it is a very natural view. After all, we can imagine leaving our bodies behind. And many traditional religious and mystical practices involve actually cultivating this feeling of entering a kind of dream state or state in which the spirit is able to travel independently of the body. In fact, even dreaming can be seen as being exactly that.

And at the same time, it goes back to the mortality paradox that we talked about earlier - the idea that we - even though we know death is a fact, at the same time we can't imagine ceasing to exist. Well, if I say to you - OK, death is a fact, but only for your body and you can't imagine ceasing to exist because your soul doesn't cease to exist and that's the real you, then we've solved the mortality paradox very neatly. So it's a kind of - it's a belief that hooks very easily onto our intuitions.

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VEDANTAM: One problem that advocates for the soul narrative have encountered is modern astronomy, if you will, starting with the Copernican Revolution. Because one question that the soul narrative poses is where do souls go?

CAVE: Nowadays, asking the question, you know, where to souls go, seems - and suggesting it might be, you know, over the mountain - sounds a little absurd, like one sort of misunderstood the concept. But actually, for the greater part of human history, it was imagined that souls would be somewhere we could point to geographically. It might be under the earth. Or it might be on some distant island. Or it might be on the moon. But there was a place. You know, when astronauts first went into space, they noted that there were no souls up there whereas Dante, in the "Divine Comedy," describes in great detail where he thought all the souls were.

So it seems that we've been looking for this place. Humans have been theorizing and speculating about this place and looking for it for many centuries. And now we've explored them all and peered with our telescopes into the far ends of the universe. We've come to the conclusion, well, they're not in this realm. They must be in a different realm. Well, OK, but what exactly does that mean? What does it mean to say they're in a different dimension or a different realm? What makes that more than just empty words? Why is that not just an admission of defeat?

VEDANTAM: So in some ways, Stephen, Buddhism and Hinduism have solutions to these problems. They say that souls don't hang out in some secret place, but they migrate into a new body. In other words, they are reincarnated. You describe how this happens in the book through the story of one little boy whose name was Lhamo Thondup. Tell me that story please.

CAVE: So after the 13th Dalai Lama died, it was, of course, very important to the monks of Tibet to find where his soul had gone, where it had been reincarnated. And so they travelled the land for many months looking for children who would have been born at about the same time - bodies that might have been the right receptacles for this soul if you like. And so when, after months travelling through snowy mountain passes, they came to a house where they heard a boy had been born two years ago at almost exactly the right time, they were very interested.

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VEDANTAM: One of the monks got the impression that the boy recognized him. Excited that this meant the boy was the reincarnated Dalai Lama, the monks left and came back with a large contingent.

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CAVE: And so they put a variety of objects out in front of the boy, some of which had belonged to the Dalai Lama and some of which were just ordinary copies that hadn't - rosaries and walking sticks and prayer drums and the likes. First, the boy picked up the right rosaries and put them around his neck. And then, he reached out towards the wrong stick and was about to pick it up, then changed his mind and picked up the Dalai Lama's stick. And all the monks celebrated and cried and believed they'd found the 14th Dalai Lama.

VEDANTAM: So do you think that the soul narrative, this immortality narrative, actually solves the mortality paradox successfully, or are there problems with it?

CAVE: Well, unfortunately, you might not be surprised to hear me say that it has problems, too. And, again, philosophers and theologians have been debating these problems for many thousands of years. Of course, it's easy for most humans to imagine a soul-like thing resides somewhere within them. But actually, from a philosophical point of view, it's very hard to say what a soul is, where it is, what makes mine different from yours, what it's made from and so forth. And we are yet to imagine that this immaterial thing that no one's ever seen, that we don't have any very clear or obvious evidence for actually is the real me. And philosophers for thousands of years as they have been skeptical about this, but now, today, we have additional reasons to be skeptical. And this is because, you know, for many thousands of years people have used the idea of the soul to explain the fact that we are thinking, conscious beings, you know?

It seems mysterious that we humans have intellect and memory and so forth. We don't think rocks or plants have those things. Well, what is it that enables us to have these powers? Well, it's because we have a soul - at least the story has been for a long time. But now, of course, we understand the brain much better than people previously. Although there are still many mysteries, there's still much we don't understand. Nonetheless, we do know that our mental faculties, like memory and beliefs, even things like a sense of right and wrong, our capacity for emotion - all of these different faculties actually correlate to bits of the brain.

We know this from various sources. One of them is brain lesions and brain tumors. And we can see that if a certain chunk of their brain has been destroyed, they can't speak or they've lost their sense of humor or they've lost certain memories or ability to think about the future and so on. My own father died of a brain tumor and I could see the ways in which - as the tumor ate up his brain, it was changing his personality. Well, this is a very profound problem for those who think that the real me, the real you, actually, is our souls. I mean, if my father had a soul that was the real him that could preserve his personality and memories and beliefs, et cetera, on into the afterlife, why couldn't it do that just when part of his brain was being damaged by a brain tumor?

VEDANTAM: So we've looked at three of your immortality narratives - the idea of rejuvenation, the idea of resurrection and the idea of reincarnation. And this brings us to our last strategy. You introduce the idea in the book by describing some of the exploits of Alexander the Great. Recount some of that history to me, if you remember it, and tell me what it says about the final immortality narrative.

CAVE: So Alexander the Great was, of course, one of the great Greek heroes. And he knew that from the start, and that was his ambition from the start. So he grew up reading about the exploits of Achilles and the other great Greek heroes, and he wanted to become one of them. He wanted to become one of those great Greek heroes. He was self-mythologizing. He wanted to become part of the Pantheon. And if we remember the story of Achilles, you know, the great Greek warrior who fought at Troy, when Achilles himself was on the beach at Troy, he faced a choice. He knew - because it had been prophesied by his mom, who was a goddess - that he could stay and fight at Troy. And if he did, he'd become a legend, known as the greatest warrior of all time, and his story would be told forever.

Or he could just go home and be king of a minor kingdom and have children and go hunting and live a long and happy life. And of course, he chose to stay and fight and die. And here we are talking about him many thousands of years later. Now, Alexander the Great knew this story inside out. And he even claimed some kind of lineage from Achilles, from his mother's side and a few other gods, as well. And he set out to beat Achilles himself, to become an even greater legend.

And so all of Alexander's exploits - and we see him as a great conquering hero, of course, because he brought Greek civilization to much of Asia. But of course, he killed hundreds of thousands of people. He destroyed whole civilizations. He had women and children put to the sword. I mean, this was a man whose exploits were legendary but also terrible, incredibly destructive. And they were driven by this one impulse to attain a greater fame than even Achilles.

VEDANTAM: You write in the book that when Alexander left on his conquest, he made sure that his entourage included scribes, historians and sculptors. He knew it was these, not the priests and alchemists, who were the guardians of eternal life. They were the ones who controlled the realm of the symbolic, and it is only there that immortality is to be found. That's a really interesting idea, that in some ways, preserving your name, that fame itself was sort of the immortality that Alexander sought.

CAVE: Yeah. So the Greeks made a clear distinction between life, bios, which is, as we've talked about, inevitably going to fail. All living things pass away. They rot. Their time is brief. They made a distinction between that and the realm of culture, things that can be literally carved in stone or songs that can be sung, not just by one generation of bards and minstrels, but for hundreds, thousands of years. And for the Greeks it was, therefore, completely clear that immortality wasn't about trying to stay alive in your body. It's fruitless. It wasn't about resurrection and this biological body, either. That would just go the same way all over again. It was about trying to carve your name in stone, to transfer yourself from this realm of unreliable biology to the realm of culture 'cause only there could you find solidity.

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VEDANTAM: You know, eternity is a long time. And it's not clear that even those who seek fame with the determination that Alexander sought fame really can hold onto that fame for any length of time. I mean, it seems like the search for fame is itself a puny way to overcome death.

CAVE: I think it's very natural for us to think that our civilizations, which completely shape our lived reality, are somehow forever. But of course, that isn't the case. You know, the ancient Romans would certainly have thought so. The ancient Egyptians, I mean, this was a civilization that lasted for 3,000 years. But of course, 3,000 years is not forever. And it's very easy for us now to think that our civilization is so powerful and so sophisticated that surely it will carry on indefinitely. And so if we can attain some kind of fame in this society now then it will be a kind of forever.

But of course, history teaches us something very different. And maybe all of these millions of photos that we're taking of ourselves and spreading around the Internet, in just a couple of generations, we'll find they're on files that are now unreadable.

VEDANTAM: There are two underlying problems with all the immortality narratives. First, even though we seek immortality, most of us wouldn't know what to do with it if we had it. As the novelist Susan Ertz writes, millions long for immortality who don't know what to do with themselves on a rainy Sunday afternoon.

CAVE: Because of course, it's not eternity that we're seeking. What we want is just to not die. I don't want to die today. I don't want to - don't think I want to die tomorrow. But of course, if you never die today or tomorrow then you end up living forever, even if that wasn't really what you wanted. And when we try to imagine forever, the mind boggles. The mind just gives up and runs. We have no way of grasping something like eternity. And those who have speculated about it and really tried to think it through tend to come to the conclusion pretty quickly that it is going to be boring and miserable.

There's a wonderful story that Jorge Luis Borges tells in his short story, "The Immortal." It's about a Roman centurion who seeks a river that cleanses men of death.

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CAVE: And in his travels, he finally comes to this land of the troglodytes, these people who just lie in shallow pits staring at the sky. One of them has been still for so long, a bird is nesting on his chest. And the centurion wakes these people and says, you know, like, who are you? And he discovers that they are the immortals. And one of them is Homer, who wrote "The Iliad" and "The Odyssey." And he says, well, isn't that, you know, amazing? Aren't you proud of your fantastic achievements? Why are you lying here in this pit? And Homer says but don't you see it's impossible not to write "The Odyssey" at least once if you live forever?

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CAVE: And so the idea is if we all live forever, we all end up doing everything. We have every possible experience multiple times. Everything starts to blend into one. Everything becomes meaningless.

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VEDANTAM: Stephen says there is a second mistake in all the immortality narratives. They see death as a problem to be solved.

CAVE: They take the mortality paradox at face value, if you like. They say death is terrifying, on the one hand, and it's impossible to imagine not being, on the other. And so we have to try to reconcile these by not dying and keeping going indefinitely. But actually, we can really, instead, question the assumptions behind the mortality paradox. Because even though it's hard to imagine not existing, that doesn't mean we won't cease to exist.

Now, this is a difficult thought to grapple with. And I think the first person who really did grapple with it, at least, in recorded history, was the Greek philosopher Epicurus, who said, when I am here, death is not, and when death is here, I am not. And therefore, I don't have to worry about dying. So he meant that exactly because death is ceasing to exist. We don't need to think about what might come after. We don't need to think about heaven or hell or keeping it going indefinitely. We won't be around to regret not being around.

Now, because of the mortality paradox, because we cannot imagine ceasing to exist, it's very, very hard to accept this. And of course, Epicurus believed you had to kind of repeat it to yourself and as a mantra to truly live according to this insight and so be free of the fear of death.

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VEDANTAM: Philosopher Stephen Cave works at the University of Cambridge. He's the author of the book "Immortality: The Quest To Live Forever And How It Drives Civilization." Stephen, thank you for joining me today on HIDDEN BRAIN.

CAVE: Thank you. It was my pleasure.

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VEDANTAM: This week's show was produced by Laura Kwerel and edited by Tara Boyle and Jenny Schmidt. Our team includes Parth Shah, Rhaina Cohen and Thomas Lu. Our unsung hero this week is Melissa Marquis. Melissa works on our ops desk at NPR. She helps coordinate studio space for various teams and shows. Melissa is the walking definition of an unsung hero, always ready to help, always thinking about what's best for the organization. Like so many unsung heroes we have recognized on this show, we simply couldn't do what we do without her. Thanks, Melissa.

If this episode spoke to you in some way, please remember to share it with someone who isn't currently listening to HIDDEN BRAIN. If the person is new to podcasting, please take a moment to show them how easy it is to subscribe. I'm Shankar Vedantam, and this is NPR.

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