Tuesday, May 16, 2006
My Pain, My Brain - New York Times
May 14, 2006
My Pain, My Brain
By MELANIE THERNSTROM
Who hasn't wished she could watch her brain at work and make changes to it, the way a painter steps back from a painting, studies it and decides to make the sky a different hue? If only we could spell-check our brain like a text, or reprogram it like a computer to eliminate glitches like pain, depression and learning disabilities. Would we one day become completely transparent to ourselves, and — fully conscious of consciousness — consciously create ourselves as we like?
The glitch I'd like to program out of my brain is chronic pain. For the past 10 years, I have been suffering from an arthritic condition that causes chronic pain in my neck that radiates into the right side of my face and right shoulder and arm. Sometimes I picture the pain — soggy, moldy, dark or perhaps ashy, like those alarming pictures of smokers' lungs. Wherever the pain is located, it must look awful by now, after a decade of dominating my brain. I'd like to replace my forehead with a Plexiglas window, set up a camera and film my brain and (since this is my brain, I'm the director) redirect it. Cut. Those areas that are generating pain — cool it. Those areas that are supposed to be alleviating pain — hello? I need you! Down-regulate pain-perception circuitry, as scientists say. Up-regulate pain-modulation circuitry. Now.
Recently, I had a glimpse of what that reprogramming would look like. I was lying on my back in a large white plastic f.M.R.I. machine that uses ingenious new software, peering up through 3-D goggles at a small screen. I was experiencing a clinical demonstration of a new technology — real-time functional neuroimaging — used in a Stanford University study, now in its second phase, that allows subjects to see their own brain activity while feeling pain and to try to change that brain activity to control their pain.
Over six sessions, volunteers are being asked to try to increase and decrease their pain while watching the activation of a part of their brain involved in pain perception and modulation. This real-time imaging lets them assess how well they are succeeding. Dr. Sean Mackey, the study's senior investigator and the director of the Neuroimaging and Pain Lab at Stanford, explained that the results of the study's first phase, which were recently published in the prestigious Proceedings of the National Academy of Sciences, showed that while looking at the brain, subjects can learn to control its activation in a way that regulates their pain. While this may be likened to biofeedback, traditional biofeedback provides indirect measures of brain activity through information about heart rate, skin temperature and other autonomic functions, or even EEG waves. Mackey's approach allows subjects to interact with the brain itself.
"It is the mind-body problem — right there on the screen," one of Mackey's collaborators, Christopher deCharms, a neurophysiologist and a principal investigator of the study, told me later. "We are doing something that people have wanted to do for thousands of years. Descartes said, 'I think, therefore I am.' Now we're watching that process as it unfolds."
Suddenly, the machine made a deep rattling sound, and an image flickered before me: my brain. I am looking at my own brain, as it thinks my own thoughts, including these thoughts.
How does it work? I want to ask. Just as people were once puzzled by Freud's talking cure (how does describing problems solve them?), the Stanford study makes us wonder: How can one part of our brain control another by looking at it? Who is the "me" controlling my brain, then? It seems to deepen the mind-body problem, widening the old Cartesian divide by splitting the self into subject and agent.
But most of all I want to know: Will I be able to learn it?
or most of history, the idea of watching the mind at work was as fantastical as documenting a ghost. You could break into the haunted house — slice the brain open — but all you would find would be the house itself, the brain's architecture, not its invisible occupant. Photographing it with X-rays resulted only in pictures of the shell of the house, the skull. The invention of the CT scan and magnetic resonance imaging (M.R.I.) were great advances because they reveal tissue as well as bones — the wallpaper as well as the walls — but the ghost still didn't show up. Consciousness remained elusive.
A newer form of M.R.I., functional magnetic resonance imaging (f.M.R.I.), used with increasingly sophisticated software, is accomplishing this, taking "movies" of brain activity. Researchers are able to watch the brain work, as the films show parts of the brain becoming active under various stimuli by detecting areas of increased blood flow connected with the faster firing of nerve cells. These films are difficult to read; researchers puzzle over the new images like Columbus staring at the gray shoreline, thinking, India? Most of the brain is uncharted, the nature of the terrain unclear. But the voyage has been made; the technology exists. Pain — a complex perception occupying the elusive space spanning sensation, emotion and cognition — is a particularly promising area of imaging research because, researchers say, it has the potential to make great progress in a short time.
Perhaps more than any other aspect of human existence, persistent pain is experienced as something we cannot control but desperately wish we could. Acute pain serves the evolutionary function of warning us of tissue damage, but chronic pain does nothing except undo us. Pain is the primary complaint that sends people to the doctor. Of the 50-odd million sufferers in the United States, half cannot get adequate relief from their chronic pain. Many do not even have a diagnosis.
Unlike acute pain, chronic pain is now thought to be a disease of the central nervous system that may or may not correlate with any tissue damage but involves an errant reprogramming in the brain and spinal cord. The brain can generate terrible pain in a wound that is long healed, in a body that is numb and paralyzed or — in the case of phantom-limb pain — in a limb that no longer even exists.
Although there have been many theories about how pain works in the brain, it is only through neuroimaging that the process has actually been observed. It is now clear that there is no single pain center in the brain. Rather, pain is a complex, adaptive network involving 5 to 10 areas of the brain transmitting information back and forth.
This network has two pain systems: pain perception and pain modulation, which involve both overlapping and distinct brain structures. The pain-modulatory system constantly interacts with the pain-perception system, inhibiting its activity. Much chronic pain is thought to involve either an overactive pain-perception circuit or an underactive pain-modulation circuit.
Like everyone who suffers from chronic pain, I find it hard to believe that I have a pain-modulation circuit. The aspect of my pain I feel most certain about is that it is not voluntary: I cannot modulate it. And this belief is reinforced every single day that I suffer from pain, which is every day. Yet I know that pain is not a fact, like a broken bone; it's a perception, like hunger, about a physical state ("an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage," as the International Association for the Study of Pain defines it). And it's a mercurial perception; under certain circumstances the pain-modulatory system works like a spell and the brain completely blocks out pain.
Soldiers, athletes, martyrs and pilgrims engage in battles, athletic feats or acts of devotion without being distracted by the pain of injuries. When the teenage surfer Bethany Hamilton's arm was bitten off by a shark, she felt pressure, but "I didn't feel any pain — I'm really lucky, because if I felt pain, things might not have gone as well," she said (articulating one reason the modulatory system evolved: if she had thrashed about in pain, she would have bled until she drowned).
In addition to being activated by stress, the pain-modulatory system is triggered by belief. The brain will shut down pain if it believes it has been given pain relief, even when it hasn't (the placebo effect), and it will augment pain if it believes you are being hurt, even if you aren't (the nocebo effect). The brain's modulatory system relies on endogenous endorphins, its own opiatelike substances. The nature of a placebo has long been a source of speculation and debate, but neuroimaging studies have shown the way a placebo actually helps to activate the pain-modulatory system.
In a recently published study led by Dr. Jon-Kar Zubieta at the University of Michigan Medical School, the brains of 14 men were imaged after a stinging saltwater solution was injected into their jaws. They were then each given a placebo and told that it would positively relieve their pain. The men immediately felt better — and the screen showed how. Parts of the brain that release endogenous opiates lighted up. In other words, fake opiates caused the brain to dispense real ones. Like some New Age dictum, philosophy becomes chemistry; believing becomes reality; the mind unites with the body.
Other studies have shown that opiates and other medications rely on a placebo to achieve part of their effect. When subjects are covertly given strong opiates like morphine, they don't work nearly as well as they do if the subjects are told they are being given a powerful pain reliever. Even real medications require some of the brain's own bounty.
Conversely, thinking about pain creates pain. In studies at Oxford University, Irene Tracey has shown that asking subjects to think about their chronic pain, for example, increases activation in their pain-perception circuits. Distraction, on the other hand, is a great analgesic; when Tracey's volunteers were asked to engage in a complicated counting task while being subjected to a painful heat stimulus, she could watch the pain-perception matrix decrease while cognitive parts of the brain involved in counting lighted up. At McGill University, Catherine Bushnell has shown that simply listening to tones while being subjected to a heat stimulus decreased activity in the pain-perception circuit. +++
"There is an interesting irony to pain," comments Christopher deCharms, who worked with Mackey designing and carrying out the Stanford study. We were talking in his office at Omneuron, a Menlo Park medical-technology company he founded three years ago to develop clinical applications of neuroimaging. "Everyone is born with a system designed to turn off pain. There isn't an obvious mechanism to turn off other diseases like Parkinson's. With pain, the system is there, but we don't have control over the dial."
The goal of the Stanford technique is to teach people to control their dials — to activate their modulatory systems without requiring the extreme stress of fleeing from a shark or the deception of a placebo. The hope of neuroimaging therapy (as deCharms calls the Stanford technique) is that repeated practice will strengthen and eventually change the ineffective modulatory system to eliminate chronic pain, the way long-term physical therapy can change muscular weakness. The scan would thus be more than a research tool: the scan itself would be the treatment, and the subject his or her own researcher.
Only once do I recall having a glimmer of my own pain-modulatory system at work: a hidden power that emerged, dispensed with pain and then returned to some forgotten fold in my brain, where I have never been able to locate it again. The event did not take place on a battlefield or a marathon course or in a temple; it was in a basement of the Stanford University medical center three years ago. At the time, Mackey had designed an earlier study that did not use imaging technology but focused on how suggestion alters pain perception. Although I was not formally enrolled in the study, I asked if I could undergo a clinical demonstration. My experience illustrated the power of suggestion in an unexpected fashion.
A metal probe attached to the underbelly of my arm heated up and cooled down at set intervals. I was told that although the heat probe would feel uncomfortable, my skin would not be burned. During one exposure, I was instructed to think of the pain as positively as possible, during another to think of it as negatively. After each sequence, I was asked to rate my pain on a 0-to-10 scale, with 10 being the worst pain I could imagine.
Although I discovered that I could make the pain fluctuate depending on whether I was imagining that I was sunbathing or was the victim of an inquisition, I still rated all the pain as low — ranging from a 1 to a 3. If 10 was being slowly burned alive, I felt I should at least be begging for mercy to justify a rating of 5. So I insisted that Mackey turn up the dial so I could get a real response. But even during the moments when I was actively trying to imagine the pain as negatively as possible, it remained in a mental box of "not even burned," which kept it from really hurting: hurting, that is, the way a burn would.
As it turned out, I got a second-degree burn that later darkened into a square mark. Mackey was more than a little dismayed as we watched the reddening skin pucker, but I was thrilled. Naturally the protocol had been carefully designed not to injure anyone, yet in my case that protection had failed because of the very phenomenon it was designed to study: expectation — the effect of the mind on pain or placebo.
I had recently spent several weeks observing Mackey in the university's pain clinic, where he is associate director. I was so convinced that Mackey — then a tall sandy-haired 39-year-old with a deep interest in technology (he got a Ph.D. in electrical engineering before he went to medical school) and an air of radiant integrity — would not burn me that my brain had not perceived the stimulus as a threat and generated pain. I admired him, I trusted him, I was positive that he wouldn't hurt me. And, ipso facto, he hadn't.
Mackey's genius as a practitioner, I thought, lay partly in his ability to similarly inspire patients. "When I started working with pain patients, I realized how much of the treatment involved trying to reverse learned helplessness," he said — to rally them out of the despair ingrained from years of unremitting pain and cajole their minds to chip in its own analgesic to their therapies. "The purpose of this study is to show patients their mind matters," Mackey said.
The mark of the burn is barely visible now, but for a couple of years afterward, at times when my chronic pain was making me miserable, the sight of it would both encourage and reproach me. Here is the ultimate proof that my mind can control pain, I would think, yet I didn't know how to make it wake up and do so. I could take the edge off the pain by conjuring positive images, but the effects didn't last, and I never again had the remarkable placebo response that masked a second-degree burn. In fact, a mild burn from spilling tea on my hand one day brought tears to my eyes.
When the real-time neuroimaging study began, I couldn't wait to try it.
The area of the brain that the scanner focuses on is the rostral anterior cingulate cortex (rACC). The rACC (a quarter-size patch in the middle-front of the brain, the cingular cortex) plays a critical role in the awareness of the nastiness of pain: the feeling of dislike for it, a loathing so intense that you are immediately compelled to try to make it stop. Indeed, the pain of pain, you might say, its defining element, is the way in which the sensation is suffused with a particular unpleasantness researchers refer to as dysphoria. Since pain is a perception, it's not pain if you don't experience it as hurting. You can feel hot or cold or pressure, and note them simply as stimuli, but when they exceed a certain intensity, the rACC kicks in, and suddenly they become painful, riveting your attention and causing you to recoil.
Many pain-reducing techniques aim to manipulate the conscious awareness of pain. Distraction, placebo, meditation, imagining pleasant scenes and hypnosis all result in a reduction of rACC activation when they work. Patients who have undergone a radical surgical treatment occasionally used for pain (as well as for mental illness) called a cingulotomy, in which the rACC is partly destroyed, report that they are still aware of pain but that they don't "mind" it anymore. Their emotional response has receded.
The image I saw while lying in the f.M.R.I. machine at the time of the recent Stanford study was not literally my rACC but a visual analogue of it that is easier to see: a 3-D image of a fire. The flames represent the degree of activation in your rACC: when it is low, the flames are low; when rACC activation is high, the flames flare. The study involves five 13-minute scanning runs, each consisting of five cycles of a 30-second rest followed by a 1-minute interval in which you try to increase rACC activation and then a 1-minute interval in which you try to decrease rACC activation.
Before my scan began, I was prepped in different mental strategies for increasing and modulating my pain. Everyone's brain works a bit differently, though, so subjects have to experiment in the scanner to see what is most effective for them. For some, trying to distract themselves from their pain works best; for others, focusing on their pain — like embracing a Zen koan — seems to be what triggers their pain-modulatory system. When deCharms used neuroimaging therapy on himself to try to alleviate his chronic neck pain, he concentrated on the pain itself and felt it "suddenly melt away." He said that a patient described the feeling as being "like a runner's high" (a state that has been shown to involve the release of endogenous endorphins).
Increase Your Pain, the screen commanded, as the first run began. I tried to recall the mental strategies in which I had been prepped for increasing pain: Dwell on how hopeless, depressed or lonely you felt when your pain was most severe. Sense that the pain is causing long-term damage.
Dwelling on the hopeless loneliness of my pain certainly made the flames of my rACC spark. The mental image that I found increased my pain the most, however, was the one that matched the visual analogue of the rACC: Picture a hot flame on your painful area. Try to make the flame grow in the painful area, and imagine it actually burning your flesh.
Having recently read Ariel Glucklich's extraordinary "Sacred Pain," I had plenty of details of the burning of heretics and witches available to me. I had only to imagine the smell of sizzling hair to make the flames of my rACC explode.
Decrease Pain, the screen commanded.
The suggested pain-reduction strategies, however, did little to quell the flames on the screen. I pictured suffocating the pain with banal positive imagery: flowing water or honey, something soft and gentle, but my mind kept slipping back to the progress of the auto-da-fé, and the rACC fire flared.
Feel that sensation, but tell yourself that it is just a completely harmless, short-term tactile sensation.
Pilgrims and devotees all around the world choose to inflict pain upon themselves during sacred rites — from being nailed to crosses to dangling from hooks. For them, pain is an occasion for euphoria, not dysphoria. There are many historical records of the equanimity saints and martyrs often possessed during torture. The second-century Jewish martyr Rabbi Akiva, for example, continued to recite a prayer with a smile on his lips while the flesh was being combed from his bones. "All my life," he explained to the puzzled Roman general orchestrating his execution, "when I said the words 'You shall love the Lord your God with all your heart, with all your soul, and with all your might,' I was saddened, for I thought, When shall I be able to fulfill this command? Now that I am giving my life and my resolution remains firm, should I not smile?"
As Glucklich writes, the conviction that pain is a spiritual opportunity seems paradoxically anesthetizing — or, as a scientist would say, religious states of conviction can robustly activate the pain-modulatory system.
During my next Decrease Pain interval, instead of trying to picture a vacation, I imagined myself as a martyr, lucidly reciting Though I walk through the valley of the shadow of death while being burned at the stake. My rACC activation — I noted — respectfully quieted. Then I remembered that the 23rd Psalm seems to have Christian associations, and since I was presumably being tortured for being half-Jewish, a Jewish prayer might be more appropriate. Unless, that is, I was being accused of witchcraft, in which case, I might be generally disillusioned with Judeo-Christian prayer. As I tried to settle on a fantasy, I noticed that my rACC stayed low: Irene Tracey's theory of the modulating effects of distraction. By the last run, I had the strategies down — heretic-martyr: rACC down; heretic-victim: rACC up.
The results of the scan, Mackey showed me, revealed significant brain control. A week later, I was scanned again, this time in the offices of Omneuron. I could feel that it was easier to control my rACC with less reliance on elaborate fantasy; I was interacting more directly with my brain.
his learning effect was clearly seen in the recent Stanford study (which was financed in part by the National Institutes of Health). The first phase of the study looked at 12 subjects with chronic pain and 36 healthy subjects. (The healthy participants were subjected to a painful heat stimulus in the scanner and tried to modulate their responses. The chronic-pain patients, however, simply worked to reduce their own pain.) The chronic-pain patients who underwent neuroimaging training reported an average decrease of 64 percent in pain rating by the end of the study. (Healthy subjects also reported a significant increase in their ability to control the pain.)
"One big concern we had," Mackey says, "is, Were we creating the world's most expensive placebo?" To ensure against that, Mackey trained a control group in pain-reduction techniques without using the scanner (as in his previous study) to see if that was as effective as employing a $2 million machine. Mackey also tried scanning subjects without showing them their brain images or tricking subjects by feeding them images of irrelevant parts of the brain or feeding them someone else's brain images. "None of these worked," Mackey says, "or worked nearly as well." Traditional biofeedback also compared unfavorably; changes in pain ratings of subjects in the experimental group were three times as large as in the biofeedback control group.
The second phase of the study, which is now under way, is designed to assess whether neuroimaging therapy offers long-term practical benefits to a larger group of chronic-pain patients. After the six sessions designed to teach them to regulate their pain, they will be observed for at least six months. The idea is to see whether they can fundamentally change their modulation system so that it can reduce pain all the time without constantly and consciously thinking about it. If so, the technique would not simply provide shelter from the storm of pain; it would bring about climate change.
"I believe the technique may make lasting changes because the brain is a machine designed to learn," deCharms says. The brain is soft-wired (plastic) rather than hard-wired: whenever you learn something new, new neural connections are believed to form and old, unused ones to wither away. (Researchers refer to this as activity-dependent neuroplasticity.) In other words, if you actively engage a certain brain region, you can alter it.
Many diseases of the central nervous system involve inappropriate levels of activation in particular brain regions that change the way they operate (negative neuroplasticity). Some regions experience atrophy, while other regions become hyperactive. (For example, epilepsy involves hyperactivity of cells; stroke, Parkinson's and other diseases involve the atrophy of nerve cells.) With chronic pain, it is believed that additional nerve cells, recruited for transmitting pain, create more pain pathways in the nervous system, while nerve cells that normally inhibit or slow the signaling, decrease or change function.
In addition, chronic pain results in a significant loss of other kinds of brain cells. A. Vania Apkarian at Northwestern University found that while the brain of a healthy person shrinks 2.5 percent a year, in a person with chronic back pain, it shrinks an additional 1.3 percent annually in the areas that involve rational thinking. I know chronic pain interferes with my concentration at times, but I never imagined that it could be truly impairing it! The Stanford technique may mitigate this harm by teaching people how to increase the efficacy of the healthy cells.
Moreover, the technique may offer a particular advantage over drug therapy. It is very difficult to design drugs to fix a problem in a specific region of the brain because the receptors that drugs target, like the opiate receptors, generally appear in multiple systems throughout the brain (which is partly why drugs almost always have side-effects). Neuroimaging therapy, on the other hand, is designed to teach control of a localized brain region.
"The technique gives people a tool they didn't know they had," Mackey says, "cognitive control over neuroplasticity. We don't fully understand how this feedback mechanism is working, but it provides tangible evidence that people can change something in their own brains, which can be very empowering. It takes Buddhist monks 30 years of sitting on a mountain learning to control their brains through meditation — we're trying to jump-start that process." As to how exactly it works — how the decision-making parts of the brain (the prefrontal regions of the cortex) cause the change in the rACC — "Heck if I know!" he says. "How do we get the brain to do anything? We can map out the anatomical circuits involved and the general functions of those circuits, but we can't tell you the mechanism by which any cognitive decision is translated into action."
If neuroimaging therapy could treat pain, could it rewire the brain to fix other diseases, like depression, stroke and learning disabilities, or exercise the brain in ways that would make it cleverer and more adept at certain skills? Neuroimaging has shown, for example, that the part of the brains of London cabdrivers that regulates spatial relations is larger than usual and that learning to juggle creates visible changes in parts of the brain involved with motor coordination during three months of training. I'm constantly getting lost and dropping things. Could I exercise and strengthen those areas more quickly by, say, thinking about maps in the scanner than by driving around London?
"What is the limit to neuroimaging therapy?" deCharms muses. "Could you learn to target the reward or serotonin system and up-regulate happiness? Could you augment psychotherapy by allowing the patient and the therapist to watch the brain?" — an idea Omneuron is already exploring, by bringing therapists and patients to the scanner and imaging patients' brains as they undergo the sessions. "After all, talk therapy is about learning to understand thought processes — to understand neural substrates and change them," he says.
How deep can the insights that functional imaging might offer really go?
What I'd like to do most is not fix problems or improve skills but use imaging as a vehicle for self-transparency. Instead of puzzling about my motivations, I'd like to be able to read my mind completely, like a book: for imaging to be the Plexiglas window through which I could finally see the ghost.
"Hmm," Dr. Scott Fishman, chief of the pain-medicine division at the University of California, Davis, said dubiously when I brought up this notion. "I'm not sure that functional imaging is actually looking at the mind. The mind is like a virtual organ — it doesn't have a physical address that we know about. Functional imaging provides a two-dimensional snapshot of a three-dimensional or a four-dimensional event of this entity of the mind. Right now, imaging is just looking at the brain; we have to be honest about that." Imaging shows the level of activation of different parts of the brain, from which we can extrapolate something about the mind, he points out, "but what we really need to see is how the parts talk to each other — and the complex nuances of their language."
The brain has more than a hundred billion neurons. All functional imaging can tell us now is that a few hundred million of them in various areas become more active at certain times. It's as if you were trying to conduct a symphony by watching a silent film of the concert. You would see the players in the bass section active at one moment, vigorously gesturing, and then the rest of the orchestra would join in, but you couldn't hear the notes or how they form strands of melody and harmony and meld together to create the ethereal experience.
"Consciousness is not neurons firing — consciousness is a transcendent emergent phenomenon that depends on the firing of neurons," says Dr. Daniel Carr, an eminent pain researcher who is now the C.E.O. of Javelin Pharmaceuticals. "The gears of a watch rotate and keep time, but the turning of the gears is not time. The question is, Is neuroimaging a picture of the experience of consciousness or is it a picture of a mechanism associated with that experience? Can there actually be a picture of an experience? Does a picture of a funeral or a wedding show you experiences? Or is there an unbridgeable gap there because you need to already understand the experience in order to interpret the photos? If a higher being told us how consciousness works, could we understand the explanation?"
Melanie Thernstrom is a contributing writer for the magazine. She is working on a book about pain.
May 14, 2006
My Pain, My Brain
By MELANIE THERNSTROM
Who hasn't wished she could watch her brain at work and make changes to it, the way a painter steps back from a painting, studies it and decides to make the sky a different hue? If only we could spell-check our brain like a text, or reprogram it like a computer to eliminate glitches like pain, depression and learning disabilities. Would we one day become completely transparent to ourselves, and — fully conscious of consciousness — consciously create ourselves as we like?
The glitch I'd like to program out of my brain is chronic pain. For the past 10 years, I have been suffering from an arthritic condition that causes chronic pain in my neck that radiates into the right side of my face and right shoulder and arm. Sometimes I picture the pain — soggy, moldy, dark or perhaps ashy, like those alarming pictures of smokers' lungs. Wherever the pain is located, it must look awful by now, after a decade of dominating my brain. I'd like to replace my forehead with a Plexiglas window, set up a camera and film my brain and (since this is my brain, I'm the director) redirect it. Cut. Those areas that are generating pain — cool it. Those areas that are supposed to be alleviating pain — hello? I need you! Down-regulate pain-perception circuitry, as scientists say. Up-regulate pain-modulation circuitry. Now.
Recently, I had a glimpse of what that reprogramming would look like. I was lying on my back in a large white plastic f.M.R.I. machine that uses ingenious new software, peering up through 3-D goggles at a small screen. I was experiencing a clinical demonstration of a new technology — real-time functional neuroimaging — used in a Stanford University study, now in its second phase, that allows subjects to see their own brain activity while feeling pain and to try to change that brain activity to control their pain.
Over six sessions, volunteers are being asked to try to increase and decrease their pain while watching the activation of a part of their brain involved in pain perception and modulation. This real-time imaging lets them assess how well they are succeeding. Dr. Sean Mackey, the study's senior investigator and the director of the Neuroimaging and Pain Lab at Stanford, explained that the results of the study's first phase, which were recently published in the prestigious Proceedings of the National Academy of Sciences, showed that while looking at the brain, subjects can learn to control its activation in a way that regulates their pain. While this may be likened to biofeedback, traditional biofeedback provides indirect measures of brain activity through information about heart rate, skin temperature and other autonomic functions, or even EEG waves. Mackey's approach allows subjects to interact with the brain itself.
"It is the mind-body problem — right there on the screen," one of Mackey's collaborators, Christopher deCharms, a neurophysiologist and a principal investigator of the study, told me later. "We are doing something that people have wanted to do for thousands of years. Descartes said, 'I think, therefore I am.' Now we're watching that process as it unfolds."
Suddenly, the machine made a deep rattling sound, and an image flickered before me: my brain. I am looking at my own brain, as it thinks my own thoughts, including these thoughts.
How does it work? I want to ask. Just as people were once puzzled by Freud's talking cure (how does describing problems solve them?), the Stanford study makes us wonder: How can one part of our brain control another by looking at it? Who is the "me" controlling my brain, then? It seems to deepen the mind-body problem, widening the old Cartesian divide by splitting the self into subject and agent.
But most of all I want to know: Will I be able to learn it?
or most of history, the idea of watching the mind at work was as fantastical as documenting a ghost. You could break into the haunted house — slice the brain open — but all you would find would be the house itself, the brain's architecture, not its invisible occupant. Photographing it with X-rays resulted only in pictures of the shell of the house, the skull. The invention of the CT scan and magnetic resonance imaging (M.R.I.) were great advances because they reveal tissue as well as bones — the wallpaper as well as the walls — but the ghost still didn't show up. Consciousness remained elusive.
A newer form of M.R.I., functional magnetic resonance imaging (f.M.R.I.), used with increasingly sophisticated software, is accomplishing this, taking "movies" of brain activity. Researchers are able to watch the brain work, as the films show parts of the brain becoming active under various stimuli by detecting areas of increased blood flow connected with the faster firing of nerve cells. These films are difficult to read; researchers puzzle over the new images like Columbus staring at the gray shoreline, thinking, India? Most of the brain is uncharted, the nature of the terrain unclear. But the voyage has been made; the technology exists. Pain — a complex perception occupying the elusive space spanning sensation, emotion and cognition — is a particularly promising area of imaging research because, researchers say, it has the potential to make great progress in a short time.
Perhaps more than any other aspect of human existence, persistent pain is experienced as something we cannot control but desperately wish we could. Acute pain serves the evolutionary function of warning us of tissue damage, but chronic pain does nothing except undo us. Pain is the primary complaint that sends people to the doctor. Of the 50-odd million sufferers in the United States, half cannot get adequate relief from their chronic pain. Many do not even have a diagnosis.
Unlike acute pain, chronic pain is now thought to be a disease of the central nervous system that may or may not correlate with any tissue damage but involves an errant reprogramming in the brain and spinal cord. The brain can generate terrible pain in a wound that is long healed, in a body that is numb and paralyzed or — in the case of phantom-limb pain — in a limb that no longer even exists.
Although there have been many theories about how pain works in the brain, it is only through neuroimaging that the process has actually been observed. It is now clear that there is no single pain center in the brain. Rather, pain is a complex, adaptive network involving 5 to 10 areas of the brain transmitting information back and forth.
This network has two pain systems: pain perception and pain modulation, which involve both overlapping and distinct brain structures. The pain-modulatory system constantly interacts with the pain-perception system, inhibiting its activity. Much chronic pain is thought to involve either an overactive pain-perception circuit or an underactive pain-modulation circuit.
Like everyone who suffers from chronic pain, I find it hard to believe that I have a pain-modulation circuit. The aspect of my pain I feel most certain about is that it is not voluntary: I cannot modulate it. And this belief is reinforced every single day that I suffer from pain, which is every day. Yet I know that pain is not a fact, like a broken bone; it's a perception, like hunger, about a physical state ("an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage," as the International Association for the Study of Pain defines it). And it's a mercurial perception; under certain circumstances the pain-modulatory system works like a spell and the brain completely blocks out pain.
Soldiers, athletes, martyrs and pilgrims engage in battles, athletic feats or acts of devotion without being distracted by the pain of injuries. When the teenage surfer Bethany Hamilton's arm was bitten off by a shark, she felt pressure, but "I didn't feel any pain — I'm really lucky, because if I felt pain, things might not have gone as well," she said (articulating one reason the modulatory system evolved: if she had thrashed about in pain, she would have bled until she drowned).
In addition to being activated by stress, the pain-modulatory system is triggered by belief. The brain will shut down pain if it believes it has been given pain relief, even when it hasn't (the placebo effect), and it will augment pain if it believes you are being hurt, even if you aren't (the nocebo effect). The brain's modulatory system relies on endogenous endorphins, its own opiatelike substances. The nature of a placebo has long been a source of speculation and debate, but neuroimaging studies have shown the way a placebo actually helps to activate the pain-modulatory system.
In a recently published study led by Dr. Jon-Kar Zubieta at the University of Michigan Medical School, the brains of 14 men were imaged after a stinging saltwater solution was injected into their jaws. They were then each given a placebo and told that it would positively relieve their pain. The men immediately felt better — and the screen showed how. Parts of the brain that release endogenous opiates lighted up. In other words, fake opiates caused the brain to dispense real ones. Like some New Age dictum, philosophy becomes chemistry; believing becomes reality; the mind unites with the body.
Other studies have shown that opiates and other medications rely on a placebo to achieve part of their effect. When subjects are covertly given strong opiates like morphine, they don't work nearly as well as they do if the subjects are told they are being given a powerful pain reliever. Even real medications require some of the brain's own bounty.
Conversely, thinking about pain creates pain. In studies at Oxford University, Irene Tracey has shown that asking subjects to think about their chronic pain, for example, increases activation in their pain-perception circuits. Distraction, on the other hand, is a great analgesic; when Tracey's volunteers were asked to engage in a complicated counting task while being subjected to a painful heat stimulus, she could watch the pain-perception matrix decrease while cognitive parts of the brain involved in counting lighted up. At McGill University, Catherine Bushnell has shown that simply listening to tones while being subjected to a heat stimulus decreased activity in the pain-perception circuit. +++
"There is an interesting irony to pain," comments Christopher deCharms, who worked with Mackey designing and carrying out the Stanford study. We were talking in his office at Omneuron, a Menlo Park medical-technology company he founded three years ago to develop clinical applications of neuroimaging. "Everyone is born with a system designed to turn off pain. There isn't an obvious mechanism to turn off other diseases like Parkinson's. With pain, the system is there, but we don't have control over the dial."
The goal of the Stanford technique is to teach people to control their dials — to activate their modulatory systems without requiring the extreme stress of fleeing from a shark or the deception of a placebo. The hope of neuroimaging therapy (as deCharms calls the Stanford technique) is that repeated practice will strengthen and eventually change the ineffective modulatory system to eliminate chronic pain, the way long-term physical therapy can change muscular weakness. The scan would thus be more than a research tool: the scan itself would be the treatment, and the subject his or her own researcher.
Only once do I recall having a glimmer of my own pain-modulatory system at work: a hidden power that emerged, dispensed with pain and then returned to some forgotten fold in my brain, where I have never been able to locate it again. The event did not take place on a battlefield or a marathon course or in a temple; it was in a basement of the Stanford University medical center three years ago. At the time, Mackey had designed an earlier study that did not use imaging technology but focused on how suggestion alters pain perception. Although I was not formally enrolled in the study, I asked if I could undergo a clinical demonstration. My experience illustrated the power of suggestion in an unexpected fashion.
A metal probe attached to the underbelly of my arm heated up and cooled down at set intervals. I was told that although the heat probe would feel uncomfortable, my skin would not be burned. During one exposure, I was instructed to think of the pain as positively as possible, during another to think of it as negatively. After each sequence, I was asked to rate my pain on a 0-to-10 scale, with 10 being the worst pain I could imagine.
Although I discovered that I could make the pain fluctuate depending on whether I was imagining that I was sunbathing or was the victim of an inquisition, I still rated all the pain as low — ranging from a 1 to a 3. If 10 was being slowly burned alive, I felt I should at least be begging for mercy to justify a rating of 5. So I insisted that Mackey turn up the dial so I could get a real response. But even during the moments when I was actively trying to imagine the pain as negatively as possible, it remained in a mental box of "not even burned," which kept it from really hurting: hurting, that is, the way a burn would.
As it turned out, I got a second-degree burn that later darkened into a square mark. Mackey was more than a little dismayed as we watched the reddening skin pucker, but I was thrilled. Naturally the protocol had been carefully designed not to injure anyone, yet in my case that protection had failed because of the very phenomenon it was designed to study: expectation — the effect of the mind on pain or placebo.
I had recently spent several weeks observing Mackey in the university's pain clinic, where he is associate director. I was so convinced that Mackey — then a tall sandy-haired 39-year-old with a deep interest in technology (he got a Ph.D. in electrical engineering before he went to medical school) and an air of radiant integrity — would not burn me that my brain had not perceived the stimulus as a threat and generated pain. I admired him, I trusted him, I was positive that he wouldn't hurt me. And, ipso facto, he hadn't.
Mackey's genius as a practitioner, I thought, lay partly in his ability to similarly inspire patients. "When I started working with pain patients, I realized how much of the treatment involved trying to reverse learned helplessness," he said — to rally them out of the despair ingrained from years of unremitting pain and cajole their minds to chip in its own analgesic to their therapies. "The purpose of this study is to show patients their mind matters," Mackey said.
The mark of the burn is barely visible now, but for a couple of years afterward, at times when my chronic pain was making me miserable, the sight of it would both encourage and reproach me. Here is the ultimate proof that my mind can control pain, I would think, yet I didn't know how to make it wake up and do so. I could take the edge off the pain by conjuring positive images, but the effects didn't last, and I never again had the remarkable placebo response that masked a second-degree burn. In fact, a mild burn from spilling tea on my hand one day brought tears to my eyes.
When the real-time neuroimaging study began, I couldn't wait to try it.
The area of the brain that the scanner focuses on is the rostral anterior cingulate cortex (rACC). The rACC (a quarter-size patch in the middle-front of the brain, the cingular cortex) plays a critical role in the awareness of the nastiness of pain: the feeling of dislike for it, a loathing so intense that you are immediately compelled to try to make it stop. Indeed, the pain of pain, you might say, its defining element, is the way in which the sensation is suffused with a particular unpleasantness researchers refer to as dysphoria. Since pain is a perception, it's not pain if you don't experience it as hurting. You can feel hot or cold or pressure, and note them simply as stimuli, but when they exceed a certain intensity, the rACC kicks in, and suddenly they become painful, riveting your attention and causing you to recoil.
Many pain-reducing techniques aim to manipulate the conscious awareness of pain. Distraction, placebo, meditation, imagining pleasant scenes and hypnosis all result in a reduction of rACC activation when they work. Patients who have undergone a radical surgical treatment occasionally used for pain (as well as for mental illness) called a cingulotomy, in which the rACC is partly destroyed, report that they are still aware of pain but that they don't "mind" it anymore. Their emotional response has receded.
The image I saw while lying in the f.M.R.I. machine at the time of the recent Stanford study was not literally my rACC but a visual analogue of it that is easier to see: a 3-D image of a fire. The flames represent the degree of activation in your rACC: when it is low, the flames are low; when rACC activation is high, the flames flare. The study involves five 13-minute scanning runs, each consisting of five cycles of a 30-second rest followed by a 1-minute interval in which you try to increase rACC activation and then a 1-minute interval in which you try to decrease rACC activation.
Before my scan began, I was prepped in different mental strategies for increasing and modulating my pain. Everyone's brain works a bit differently, though, so subjects have to experiment in the scanner to see what is most effective for them. For some, trying to distract themselves from their pain works best; for others, focusing on their pain — like embracing a Zen koan — seems to be what triggers their pain-modulatory system. When deCharms used neuroimaging therapy on himself to try to alleviate his chronic neck pain, he concentrated on the pain itself and felt it "suddenly melt away." He said that a patient described the feeling as being "like a runner's high" (a state that has been shown to involve the release of endogenous endorphins).
Increase Your Pain, the screen commanded, as the first run began. I tried to recall the mental strategies in which I had been prepped for increasing pain: Dwell on how hopeless, depressed or lonely you felt when your pain was most severe. Sense that the pain is causing long-term damage.
Dwelling on the hopeless loneliness of my pain certainly made the flames of my rACC spark. The mental image that I found increased my pain the most, however, was the one that matched the visual analogue of the rACC: Picture a hot flame on your painful area. Try to make the flame grow in the painful area, and imagine it actually burning your flesh.
Having recently read Ariel Glucklich's extraordinary "Sacred Pain," I had plenty of details of the burning of heretics and witches available to me. I had only to imagine the smell of sizzling hair to make the flames of my rACC explode.
Decrease Pain, the screen commanded.
The suggested pain-reduction strategies, however, did little to quell the flames on the screen. I pictured suffocating the pain with banal positive imagery: flowing water or honey, something soft and gentle, but my mind kept slipping back to the progress of the auto-da-fé, and the rACC fire flared.
Feel that sensation, but tell yourself that it is just a completely harmless, short-term tactile sensation.
Pilgrims and devotees all around the world choose to inflict pain upon themselves during sacred rites — from being nailed to crosses to dangling from hooks. For them, pain is an occasion for euphoria, not dysphoria. There are many historical records of the equanimity saints and martyrs often possessed during torture. The second-century Jewish martyr Rabbi Akiva, for example, continued to recite a prayer with a smile on his lips while the flesh was being combed from his bones. "All my life," he explained to the puzzled Roman general orchestrating his execution, "when I said the words 'You shall love the Lord your God with all your heart, with all your soul, and with all your might,' I was saddened, for I thought, When shall I be able to fulfill this command? Now that I am giving my life and my resolution remains firm, should I not smile?"
As Glucklich writes, the conviction that pain is a spiritual opportunity seems paradoxically anesthetizing — or, as a scientist would say, religious states of conviction can robustly activate the pain-modulatory system.
During my next Decrease Pain interval, instead of trying to picture a vacation, I imagined myself as a martyr, lucidly reciting Though I walk through the valley of the shadow of death while being burned at the stake. My rACC activation — I noted — respectfully quieted. Then I remembered that the 23rd Psalm seems to have Christian associations, and since I was presumably being tortured for being half-Jewish, a Jewish prayer might be more appropriate. Unless, that is, I was being accused of witchcraft, in which case, I might be generally disillusioned with Judeo-Christian prayer. As I tried to settle on a fantasy, I noticed that my rACC stayed low: Irene Tracey's theory of the modulating effects of distraction. By the last run, I had the strategies down — heretic-martyr: rACC down; heretic-victim: rACC up.
The results of the scan, Mackey showed me, revealed significant brain control. A week later, I was scanned again, this time in the offices of Omneuron. I could feel that it was easier to control my rACC with less reliance on elaborate fantasy; I was interacting more directly with my brain.
his learning effect was clearly seen in the recent Stanford study (which was financed in part by the National Institutes of Health). The first phase of the study looked at 12 subjects with chronic pain and 36 healthy subjects. (The healthy participants were subjected to a painful heat stimulus in the scanner and tried to modulate their responses. The chronic-pain patients, however, simply worked to reduce their own pain.) The chronic-pain patients who underwent neuroimaging training reported an average decrease of 64 percent in pain rating by the end of the study. (Healthy subjects also reported a significant increase in their ability to control the pain.)
"One big concern we had," Mackey says, "is, Were we creating the world's most expensive placebo?" To ensure against that, Mackey trained a control group in pain-reduction techniques without using the scanner (as in his previous study) to see if that was as effective as employing a $2 million machine. Mackey also tried scanning subjects without showing them their brain images or tricking subjects by feeding them images of irrelevant parts of the brain or feeding them someone else's brain images. "None of these worked," Mackey says, "or worked nearly as well." Traditional biofeedback also compared unfavorably; changes in pain ratings of subjects in the experimental group were three times as large as in the biofeedback control group.
The second phase of the study, which is now under way, is designed to assess whether neuroimaging therapy offers long-term practical benefits to a larger group of chronic-pain patients. After the six sessions designed to teach them to regulate their pain, they will be observed for at least six months. The idea is to see whether they can fundamentally change their modulation system so that it can reduce pain all the time without constantly and consciously thinking about it. If so, the technique would not simply provide shelter from the storm of pain; it would bring about climate change.
"I believe the technique may make lasting changes because the brain is a machine designed to learn," deCharms says. The brain is soft-wired (plastic) rather than hard-wired: whenever you learn something new, new neural connections are believed to form and old, unused ones to wither away. (Researchers refer to this as activity-dependent neuroplasticity.) In other words, if you actively engage a certain brain region, you can alter it.
Many diseases of the central nervous system involve inappropriate levels of activation in particular brain regions that change the way they operate (negative neuroplasticity). Some regions experience atrophy, while other regions become hyperactive. (For example, epilepsy involves hyperactivity of cells; stroke, Parkinson's and other diseases involve the atrophy of nerve cells.) With chronic pain, it is believed that additional nerve cells, recruited for transmitting pain, create more pain pathways in the nervous system, while nerve cells that normally inhibit or slow the signaling, decrease or change function.
In addition, chronic pain results in a significant loss of other kinds of brain cells. A. Vania Apkarian at Northwestern University found that while the brain of a healthy person shrinks 2.5 percent a year, in a person with chronic back pain, it shrinks an additional 1.3 percent annually in the areas that involve rational thinking. I know chronic pain interferes with my concentration at times, but I never imagined that it could be truly impairing it! The Stanford technique may mitigate this harm by teaching people how to increase the efficacy of the healthy cells.
Moreover, the technique may offer a particular advantage over drug therapy. It is very difficult to design drugs to fix a problem in a specific region of the brain because the receptors that drugs target, like the opiate receptors, generally appear in multiple systems throughout the brain (which is partly why drugs almost always have side-effects). Neuroimaging therapy, on the other hand, is designed to teach control of a localized brain region.
"The technique gives people a tool they didn't know they had," Mackey says, "cognitive control over neuroplasticity. We don't fully understand how this feedback mechanism is working, but it provides tangible evidence that people can change something in their own brains, which can be very empowering. It takes Buddhist monks 30 years of sitting on a mountain learning to control their brains through meditation — we're trying to jump-start that process." As to how exactly it works — how the decision-making parts of the brain (the prefrontal regions of the cortex) cause the change in the rACC — "Heck if I know!" he says. "How do we get the brain to do anything? We can map out the anatomical circuits involved and the general functions of those circuits, but we can't tell you the mechanism by which any cognitive decision is translated into action."
If neuroimaging therapy could treat pain, could it rewire the brain to fix other diseases, like depression, stroke and learning disabilities, or exercise the brain in ways that would make it cleverer and more adept at certain skills? Neuroimaging has shown, for example, that the part of the brains of London cabdrivers that regulates spatial relations is larger than usual and that learning to juggle creates visible changes in parts of the brain involved with motor coordination during three months of training. I'm constantly getting lost and dropping things. Could I exercise and strengthen those areas more quickly by, say, thinking about maps in the scanner than by driving around London?
"What is the limit to neuroimaging therapy?" deCharms muses. "Could you learn to target the reward or serotonin system and up-regulate happiness? Could you augment psychotherapy by allowing the patient and the therapist to watch the brain?" — an idea Omneuron is already exploring, by bringing therapists and patients to the scanner and imaging patients' brains as they undergo the sessions. "After all, talk therapy is about learning to understand thought processes — to understand neural substrates and change them," he says.
How deep can the insights that functional imaging might offer really go?
What I'd like to do most is not fix problems or improve skills but use imaging as a vehicle for self-transparency. Instead of puzzling about my motivations, I'd like to be able to read my mind completely, like a book: for imaging to be the Plexiglas window through which I could finally see the ghost.
"Hmm," Dr. Scott Fishman, chief of the pain-medicine division at the University of California, Davis, said dubiously when I brought up this notion. "I'm not sure that functional imaging is actually looking at the mind. The mind is like a virtual organ — it doesn't have a physical address that we know about. Functional imaging provides a two-dimensional snapshot of a three-dimensional or a four-dimensional event of this entity of the mind. Right now, imaging is just looking at the brain; we have to be honest about that." Imaging shows the level of activation of different parts of the brain, from which we can extrapolate something about the mind, he points out, "but what we really need to see is how the parts talk to each other — and the complex nuances of their language."
The brain has more than a hundred billion neurons. All functional imaging can tell us now is that a few hundred million of them in various areas become more active at certain times. It's as if you were trying to conduct a symphony by watching a silent film of the concert. You would see the players in the bass section active at one moment, vigorously gesturing, and then the rest of the orchestra would join in, but you couldn't hear the notes or how they form strands of melody and harmony and meld together to create the ethereal experience.
"Consciousness is not neurons firing — consciousness is a transcendent emergent phenomenon that depends on the firing of neurons," says Dr. Daniel Carr, an eminent pain researcher who is now the C.E.O. of Javelin Pharmaceuticals. "The gears of a watch rotate and keep time, but the turning of the gears is not time. The question is, Is neuroimaging a picture of the experience of consciousness or is it a picture of a mechanism associated with that experience? Can there actually be a picture of an experience? Does a picture of a funeral or a wedding show you experiences? Or is there an unbridgeable gap there because you need to already understand the experience in order to interpret the photos? If a higher being told us how consciousness works, could we understand the explanation?"
Melanie Thernstrom is a contributing writer for the magazine. She is working on a book about pain.
Monday, May 01, 2006
You may be somw what moody today and these strange feelings can get in your way. But fate is hiding in the shadows and is ready to spring at the right moment to change everything. This will work out to your advantage if you can roll with the waves and relinquish the control you may think you have, but don't.
Monday, May 1, 2006
Monday, May 1, 2006
NOVA Transcripts Jewel of the Earth PBS
Jewel of the Earth
PBS Airdate: February 14, 2006Go to the companion Web site
NARRATOR: Amber: its jewel-like beauty has held humans spellbound for thousands of years, but inside an even greater treasure glows.
DAVID ATTENBOROUGH: It's hard to imagine a more perfect time capsule than this. This little bee has been trapped in there for literally millions of years.
NARRATOR: Suspended in time, these tiny prisoners have tales to tell of a world that belonged to the dinosaurs, of enemies long extinct, of supercontinents that no longer exist. Now scientists can peer deeper into these time machines than they ever did before, opening the door to the unthinkable, bringing dinosaurs back to life.
DAVID GRIMALDI (American Museum of Natural History): I was astounded at the possibility of DNA being preserved.
ROBERTA POINAR (Oregon State University): Every once in a while, in your life, you witness something that's just too spectacular for words, and this was one of the times.
NARRATOR: Host David Attenborough takes you on a quest for amber. Jewel of the Earth, right now on NOVA.
Google is proud to support NOVA in the search for knowledge: Google.
Major funding for NOVA is provided by the Howard Hughes Medical Institute, serving society through biomedical research and science education: HHMI.
Major funding for NOVA is also provided by the Corporation for Public Broadcasting, and by PBS viewers like you. Thank you.
DAVID ATTENBOROUGH: There is a substance so strange and so beautiful that whenever people encountered it, they thought they had found something magical. And its magic is real, because this material has traveled through time, bringing with it passengers from the distant past that have wonderful tales to tell.
This extraordinary substance has fascinated me since I first held a piece, this piece, when I was 12. My first piece of amber arrived in a very unexpected way.
In 1938, during the build up to the Second World War, my parents helped some of the many children fleeing from Germany. They had left their families behind and were allowed to bring almost nothing with them. I remember one girl, in particular. Her name was Marianne. She was 12, about the same age as I was, and she came from a city on the Baltic coast where her father was a doctor.
He had given her one small but precious thing, as a sign of his thanks to whoever it was who was going to look after his daughter. And this is it. It felt surprisingly warm and light in my hand, but what made me fall in love with amber was what I discovered inside it. I found something miraculous.
There were insects preserved in astonishing detail. I burned with questions. What sort of world were they from? They must have lived a long time ago, but how long? Years later, my brother Richard would play a scientist in a movie which made amber famous the world over.
RICHARD ATTENBOROUGH (Actor/John Hammond in clip from "Jurassic Park"): Welcome to Jurassic Park.
DAVID ATTENBOROUGH: Richard's character extracted DNA from dinosaur's blood trapped in amber and, with it, brought dinosaurs back to life. Could that ever be done?
SAM NEILL (Actor/Dr. Alan Grant in clip from "Jurassic Park"): How did you do this?
RICHARD ATTENBOROUGH (Actor/John Hammond in clip from "Jurassic Park"): I'll show you.
DAVID ATTENBOROUGH: I started my journey with the amber time machine by taking Marianne's gift back to where it came from, to the shores of the Baltic Sea.
The amber comes from rocks on the seabed, some distance out from the coast, but people don't find it until it washes up on the shore. Little bits like this are quite common. Sometimes, if you are lucky, particularly after a storm, you can find bigger bits. Some even have barnacles still attached to them. People have been collecting such bits for thousands of years but had no idea how amber originated. Some said it was solidified sunshine, some that it was the tears of the gods.
Then, around the year 77 A.D., a great Roman naturalist, Pliny the Elder, conducted a simple experiment. He did this.
The smell? Unmistakable: pine resin.
Several types of plants, among them conifers, seal any wound inflicted by storms or insect attack, by producing a sticky resin which oozes out from them. And because it continues to gently flow around whatever it traps, it can preserve creatures in the finest detail. As the resin hardens around its captives, they become suspended in time.
Of course, many creatures are fossilized in rock, like this small flat fish, for example. It's a kind of ray. It was squashed, its soft parts decayed, even its little spines turned into rock.
But amber preserves creatures in a quite different fashion. When this little bee touched this drop of resin she was caught by its stickiness, and she was instantly and perfectly preserved in three dimensions. These eyes saw a world which existed long before mankind evolved. She scented flowers before the first human being ever smelled one. And I can even tell that she was working hard when she died, by the bundles of cargo on her hind legs.
It's hard to imagine a more perfect time capsule than this. This little bee has been trapped in there for, literally, millions of years.
Amber's ability to travel through time can take us back into more recent history, our history. Stonehenge is one of the earliest man-made structures in the world. These stones have been standing here for something like three and a half thousand years, and we know that, even then, the people who erected them treasured amber.
But they weren't the first. It was considered to be precious way back in the Stone Age, and this may be why. When you scrape its rough surface, with a flint blade, perhaps, you quickly reveal the wonderful golden color inside. It's quite magical.
Stone Age people also carved bone and stone in order to make tools, but amber was different. It seemed to have had no practical use, so they must have valued it for some other reason.
The carvings they made, around 10,000 years ago, give us an idea of how they viewed the world, and, in particular, which animals mattered most to them. Imagine the value of amber to a Stone Age hunter who believed that capturing an animal's spirit by carving it in amber made the animal itself easier to hunt.
The people who built the great stone circle at Stonehenge lived in the Bronze Age, several thousand years later, but they, too, treasured amber. None but the wealthiest of them could afford a material as rare as this.
Once, there were a thousand beads in this necklace. Over 3,000 years, their surfaces have become opaque and crumbly. But when they were new, and freshly polished, and glowing, it must have been a wondrous piece of jewelry.
One woman's grave contained a rather more mysterious object, a disc of amber, now browned with age, encircled by gold. It was certainly a remarkable piece of personal decoration, but maybe it had a rather deeper significance.
The sun is central to our understanding of Stonehenge. The monument may have been used as a solar calendar, and it may be that its builders treasured amber, because it captured the warmth and the light of the sun. It may or may not have been considered magical in prehistoric Britain, but it was most certainly rare, for it came from far away.
This is the Baltic city of Gdansk, in Poland. The jewelry worn by the people of Stonehenge, and buried with them, came from around here. It is evidence of one of the world's first long distance trade routes.
But what brought the big boom in amber was the rise of Imperial Rome. The Romans bought it for prestige. Amber carvings cost more than the best slaves, and even the emperor Nero treasured it. He decorated his amphitheaters with tons of it, to show how unbelievably wealthy he was.
So Baltic amber can take us back at least 10,000 years into our own past, but it reaches back much further than that.
To find out how far, I went to one of the Gdansk workshops where amber jewelry is made, to meet Elzbieta Sontag.
ELZBIETA SONTAG (University of Gdansk): ...very thin, it's most probably with inclusion inside.
DAVID ATTENBOROUGH: Elzbieta is a biologist who comes here to look for "inclusions," animals and plants trapped in the amber.
It takes a practiced eye to search through as much raw amber as this, and I was delighted to get a lesson from the expert.
How do I start? I mean, there are a million pieces, all right a thousand pieces. What...is there a particular color I should look for?
ELZBIETA SONTAG: Sometime color yes, because white and milky is without inclusion.
DAVID ATTENBOROUGH: Are they good?
ELZBIETA SONTAG: No.
DAVID ATTENBOROUGH: Oh. That's bad?
ELZBIETA SONTAG: It's bad.
DAVID ATTENBOROUGH: Okay, I'm not interested in that.
ELZBIETA SONTAG: Okay, I avoid it, that kind of color.
DAVID ATTENBOROUGH: So what do I...
ELZBIETA SONTAG: I'm looking for transparent.
DAVID ATTENBOROUGH: Would that one be any good?
ELZBIETA SONTAG: Yes. I think, yes. We can split it.
DAVID ATTENBOROUGH: Ah, really?
ELZBIETA SONTAG: Oh, yes.
DAVID ATTENBOROUGH: And...
ELZBIETA SONTAG: And may be something is inside.
DAVID ATTENBOROUGH: How many pieces do you look at before you find something?
ELZBIETA SONTAG: Oh, about 20.
DAVID ATTENBOROUGH: Twenty. Eleven...
ELZBIETA SONTAG: Not good, shape is not good.
DAVID ATTENBOROUGH: Why is it the wrong shape? Twelve.
ELZBIETA SONTAG: Next one...
DAVID ATTENBOROUGH: Thirteen...spit...there's a lot of bubbles. Fourteen...
ELZBIETA SONTAG: Wow! Oh, no. Maybe.
DAVID ATTENBOROUGH: Fifteen, nothing. Yes, I think so, 16. It's a mosquito.
ELZBIETA SONTAG: No mosquito, midges.
DAVID ATTENBOROUGH: Oh, but this is beautiful. The midge looks as though it took off from its twig only yesterday. But, amazingly, it has been frozen in flight for around 40 million years.
So what about the creatures in my piece? What exactly were they? I could see them clearly, for Elzbieta's microscope had a projection screen.
Oh, well that's an old friend, because it's quite big and it's near the surface, and I've known it for a long time. So it's a fly but what kind of a fly?
ELZBIETA SONTAG: It's a long-legged fly.
DAVID ATTENBOROUGH: A long-legged fly? And in what part of the forest do they live?
ELZBIETA SONTAG: Low on the forest. Sometimes sit on the bark.
DAVID ATTENBOROUGH: So the likelihood is, then, that this fly, and therefore this piece of amber, this gum, this resin, was low down on the tree.
ELZBIETA SONTAG: Yes, low down on the floor.
DAVID ATTENBOROUGH: Okay, what else is there?
With her powerful microscope, Elzbieta was exploring far deeper into my amber than I had been able to do, and there she found another fly, a fungus gnat. It must have died searching for rotten wood, for that is where it lays its eggs.
Then Elzbieta found an aphid and, right above it, an ant. Perhaps they had fallen together from a leaf where they were feeding. I think that's a fantastic picture. I mean, I...and it's deep in the amber. I know, because I've never seen it like this before.
But the last animal she found was the most surprising. Ah, what a monster! What is it?
ELZBIETA SONTAG: There is a mite.
DAVID ATTENBOROUGH: A mite.
ELZBIETA SONTAG: Yes, a very small monster.
DAVID ATTENBOROUGH: Yes. That's tiny though, isn't it? How big is that?
ELZBIETA SONTAG: That one? Half a millimeter.
DAVID ATTENBOROUGH: Half a millimeter.
I've never seen it before. So we've got a whole community—and we know that they all lived together because, because they all died together—in my one piece of amber. And that alone has given us a whole rounded picture of a tiny little ecosystem, at the bottom of a tree, 40 million years ago.
ELZBIETA SONTAG: Exactly.
DAVID ATTENBOROUGH: Amazing. Thank you very much.
It had taken me more than 60 years to find and identify all the animals inside my amber. And seeing them together had given me something more, a glimpse of their world.
By comparing many amber animals to modern forms, scientists like Elzbieta are sure that the forest they inhabited was a temperate one. But how broad a picture can these time travelers give us? Could it encompass a whole forest or even a whole continent?
Well, in the 1960s, on a Caribbean mountainside, science discovered a new source of amber which seemed perfectly suited to answer those questions. I had a chance to visit it 15 years ago. I hoped that for the first time, I, myself, might collect some amber.
Here in the Dominican Republic, amber is mined. And by dating the mudstones that contain it, we can tell that it is about 20 million years old, rather younger than Baltic amber.
Picking a piece of amber from the mudstones in which it has lain for so long was hugely exciting. I brought a small collection back home with me. So what kind of forest did this amber come from? Well thanks to some remarkable detective work, we can answer that question in amazing detail.
In this piece, there's a leaf from the plants that produced the amber. And this is what those plants looked like. They were giant bean trees. But what matters most about them is not what they looked like but where they grew. They were tropical.
Scientists had long imagined that the ancient tropical forests contained a vast diversity of life, but very few fossilized traces had ever been found, until they discovered these.
Dominican amber preserves such a huge variety of animals and plants, with such perfection, that it inspired two scientists, George and Roberta Poinar, to try something that had previously been thought impossible. In the same way that Elzbieta reconstructed the world around a single Baltic tree, they started to use these tiny fossils to bring a whole tropical forest back to life.
I had found a piece which contained a little bee. She must have been familiar with many of the plants in that forest, indeed she depended on them. So, based on the Poinar's findings, and with a little bit of amber magic, we can follow her back home.
This tiny flower shows that the amber trees were not the only giants reaching up into the forest canopy. It belonged to a sebo, whose great trunk is supported by wide buttress roots.
But the commonest flowers of all came from a different tree, the nazareno. It seems likely that these trees dominated the forest canopy. When one of these giants fell, it would have opened up a light gap, which other, faster-growing plants could fill, plants like palms.
And here are their flowers, confirming that palms were another key element of that forest.
So we have built up a picture of what part of the forest was like and even identified some of the flowers which might have tempted my bee. But I don't think she died collecting nectar.
She was searching the forest for something else. Remember those bundles on her back legs? They are clues to what she was after. She was collecting resin, and not just any resin, but resin from the amber trees themselves. And that was a very dangerous thing to do. She was a stingless bee, very skilled at handling resin. Even so, there was a real chance that while collecting it, a bee might get stuck. Stingless bees are among the most common animals trapped in Dominican amber. Why did they take the risk?
Resin is very valuable to these bees. Mixed with plant waxes and fibers, it makes a strong building material for their nests. But it also brings another benefit. It contains antibiotics which disinfect the wounds in the bark of the tree from which it oozes. By bringing it here, into the nests, the bees protect their developing young from infection.
So now we know exactly what this little bee was doing in that forest 20 million years ago. This piece of amber has not only trapped her body, it also caught her behavior. And we know from other pieces of amber, too, that she had enemies.
This is an assassin bug. It hunts stingless bees, and their addiction to resin makes it easy for it to find them. The bug can't move swiftly enough to snatch a bee from midair, but it's strong enough to pull off strands of resin. With these sticky gloves it can hold on to any bee which touches them. It's using resin to set a trap. Now the assassin stabs its dagger-like mouthparts into a weak point behind the bee's head and injects its saliva, paralyzing the bee. As she dies, she releases a pheromone, a scent calling for help, which normally rallies other bees to defend the nest, and that entices them into the assassin's reach.
But one assassin lost its grip and now lies in amber, together with its victim. Once small animals like this were in the resin's grip they were as doomed as flies on fly paper. But, even so, amber sometimes contains animals that, normally, would never go near it.
How can George Poinar explain his next discovery? It was an amber tadpole. It couldn't have come into contact with resin underwater, yet when he looked further, he found other pond animals: a young marsh beetle, even a diving beetle.
The challenge was to explain how they had found their way into a flow of resin on the trunk of a tree. This is a poison dart frog. She is only half the size of your thumb, and, remarkably, she is carrying a tadpole on her back. She moves in a very determined and purposeful way, and starts to climb a tree.
These are what she is looking for: plants that collect water, called tank bromeliads. No one has yet found a piece of a bromeliad in amber, but we know they were there because there are amber damselflies of a kind which today lays its eggs between the tightly packed leaves of bromeliads.
She's reached a branch. Her tadpole will soon have a nursery. She lowers her rear end into the bromeliad's pond.
Other animals also lived in these tiny ponds. Up here they may have been safe from predators but not, it seems, from resin. So bromeliads held tiny complete worlds high up above the ground, but, even so, they probably didn't contain enough food to sustain a fast growing tadpole. What, then, did it eat? Amazingly the piece of amber that held the tadpole also contained the answer.
Poison dart frogs are very attentive parents. Every few days the tadpole's mother climbs back up the tree to the bromeliad to care for her youngster. She's laying an egg. That's what the other object was in the amber. These eggs are sterile and don't grow into frogs, they are food. But occasionally these little worlds up in the branches were shattered. And at least one falling tadpole came to a sticky end.
Who would have thought that amber could reveal such intimate details of life in tiny ponds high up in such trees as these?
But what about the bigger animals of the forest? Amber surely can't tell us anything about the presence or absence of these. Or can it?
Remarkably, amber does contain evidence of one such creature, thanks to some very oddly shaped seeds. These are the seeds of a kind of bamboo. The hooks on them get stuck in the hairs of animals so that the seeds travel with them and so are dispersed. But what sort of animals carried these seeds? Well, sometimes such seeds have hairs still attached to them, and the only animals with hairs are mammals.
There were certainly a number of mammals around 20 million years ago, but can these hairs help us to be a little more specific as to which mammals were here? They can.
The shape of the scales on the surface of hairs varies, and George Poinar used them to narrow down the possibilities. They came from some kind of carnivore.
It seems there were big cats in the ancient forest. Perhaps they even hunted the ancestors of modern coatis. So that's one more animal that I know that lived in that forest, but what about organisms for which there is not even a hair to serve as evidence?
Amber really is astonishing, because, as well as carrying animals' bodies through time, it can bring clues to their relationships. And that is what makes me certain that the forest contained enormous fig trees like this, although no trace of such a tree has yet been found in amber.
Let me explain. George Poinar found the crucial evidence. Exhibit A: a minute wasp. This wasp proves that the forest had figs, but to find out what makes it such a conclusive witness, we need to see what goes on today, inside the figs themselves. Although they look like fruit, figs are really containers for the tree's flowers and its developing seeds. But some also house wasps. Fig wasps spend almost all their lives inside figs, which are sealed so nothing but a fig wasp can collect their pollen. And that is how the wasps repay the fig trees for providing their nursery, by distributing their pollen.
These two organisms have come to rely on each other so closely that it's impossible for one to exist without the other. That is why a single wasp can guarantee that the forest contained fig trees. The partnership between figs and wasps is one of the most intimate in the whole of nature.
But that piece of amber had something else to reveal, something that was rather more sinister. The rear end of the wasp is surrounded by minute nematode worms. As the wasps emerge inside a fig, so do these nematodes. Each has just a few minutes to find a wasp and burrow into its body before it leaves the fig. But these are not conventional parasites. The only thing they will take from the wasps is a free ride to the next fig. Only amber could have preserved such minute details and, with them, revealed an extraordinary fact.
The relationship between the forest's fig trees, their wasps and worms, that we know today, clearly existed 20 million years ago. Amber, again and again, demonstrates this constancy.
Take this, for example. It looks like a death scene, a scale insect in the jaws of a predatory ant. But the truth is very different. Scale insects drink the stress, anxiety or panic of pods, but this takes time. Predators would soon pick them off, if it wasn't for the teams of ant bodyguards that protect them. And in exchange, the ants receive a share of the sap. By providing ants with food that they can't otherwise reach, the scale insects have made themselves indispensable. This relationship was so important that, far from eating her captive, this queen ant was gently carrying it away, so it would set up a new colony beside her own. And for 20 million years neither partner has had any reason to change.
What does this astonishing absence of change imply? If conditions had altered radically, many of these complex relationships would have disappeared. So their presence tells us that tropical forests must have existed, largely unchanged, for at least 20 million years.
But now George Poinar has traveled back even further in time. One of his latest finds in Dominican amber takes us back not just 20 million years, but 150 million, for it has implications about the Earth's geological history. And this startling new evidence comes from a single ant.
I have come across its modern relatives myself, and their behavior can tell us something unexpected about the Dominican amber forest. They are honeypot ants whose workers have become jars in which the colony stores honey to help it through times when liquid and nectar are scarce in the dry season.
So this amber honeypot ant suggests that the ancient forest also had a dry season. And if the modern ants are anything to go by, then it lasted around three to four months.
So, now, amber can tell us how often it rained 20 million years ago. But it is also evidence of an event that occurred even further back in time, because the living honeypot ants I found don't occur in the Dominican Republic or even in South America; they live in Australia.
So these little ants are evidence not only of climate, but the fact that once Australia and South America were joined together in one supercontinent. Who would have thought a single ant could tell us so much?
The amber time machine could hardly illuminate a more global event than the drift of continents, but it can also take us to the opposite extreme. What surprises might we find inside an amber animal?
Dr. David Grimaldi, of the American Museum of Natural History, is especially interested in lizards. These Anolis lizards are very territorial and the males take great risks to secure a patch of bark for themselves. They spend a lot of time displaying aggressively to one another, doing press-ups and erecting their throat flaps. And sometimes they fall. A few have achieved fame and immortality in amber, but such specimens are very rare, and not surprisingly. A lizard should be strong enough to unstick itself from a flow of resin. But some did not, and that puzzled David Grimaldi.
He wondered whether they could be as well-preserved inside as they were outside. Could he actually look inside an amber lizard? He turned to the latest high tech scanners.
DAVID GRIMALDI: These are scans that use very high intensity x-rays that are too high for medical purposes, and we have incredible detail in any view that we want. This scan of a gecko's head shows the finest details of its skull and even its teeth. Amber's preservation is clearly more than skin deep but nothing in this scan could explain why this gecko was trapped.
DAVID ATTENBOROUGH: So David Grimaldi turned to another gecko and looked at its whole body, this time with conventional x-rays.
DAVID GRIMALDI: The x-ray revealed that the bones were beautifully preserved. Bones of the skull, delicate little toe bones, bones of the leg and even individual vertebrae are revealed. But, from the jumble of bones, it is clear that the gecko's back was broken. It had probably been picked up and dropped, perhaps by a bird of prey. It didn't escape from the resin because, when it hit it, it was already dead.
DAVID ATTENBOROUGH: As researchers started finding even smaller internal details preserved by amber, they began to ask themselves something almost unthinkable. Could amber have preserved molecular structures inside an animal? Perhaps even its DNA? Some people even imagined that such DNA could bring monsters back to life. And look where that got us. But there are no remains of dinosaurs in amber. Surely their DNA is beyond our reach.
The Poinars dared to wonder if that was so. The story begins 20 years ago, when Roberta first focused an electron microscope on an amber animal. Inside a fungus gnat, like the one in my piece of Baltic amber, she discovered something quite amazing.
ROBERTA POINAR: It's like a miracle. Every once in a while, in your life, you witness something that's just too spectacular for words, and this was one of the times.
DAVID ATTENBOROUGH: The Poinars had found 40-million-year-old cells, and more than that, even the minute structures inside the cells were clear to see.
GEORGE POINAR (Oregon State University): We were kind of flabbergasted that it was possible to have such a degree of preservation after such a long time.
ROBERTA POINAR: And so I, you know, zoomed on up to a higher magnification and just was amazed to see that there were nuclei with bits of chromatin in the nucleus. And that is the step that led us to believe that DNA was there, in the cell, and could, perhaps, be pulled out and looked at.
DAVID ATTENBOROUGH: It was an astonishing discovery. The prospect of finding such ancient DNA electrified the scientific community. And Hollywood wasn't far behind. The storyline of Jurassic Park is very ingenious. My brother, who played the scientist, didn't actually need to find bits of dinosaur in amber. Nature had already extracted their DNA in blood cells and preserved it inside an amber mosquito. But that's pure fiction isn't it?
DAVID GRIMALDI: Surely it is impossible to recover DNA from any animal which lived in the distant past.
DAVID ATTENBOROUGH: Well, two teams set out to attempt exactly that. One of them included David Grimaldi. The other was set up by the Poinars. Both knew that their only chance of finding DNA was in the best-preserved animals, so the Poinars chose to use my favorites, some stingless bees, while the other team decided to work on an amber termite.
DAVID GRIMALDI: We had no expectations—at least I didn't—when we did the study. We did the extractions. We tried it. Several of the extractions were unsuccessful.
DAVID ATTENBOROUGH: But then both teams struck gold. Tissue extracted from the Poinar's bees tested positive for DNA, and David Grimaldi got the same result from the termite.
DAVID GRIMALDI: Our first reaction, particularly mine, was really disbelief. I was astounded at the possibility of DNA being preserved.
DAVID ATTENBOROUGH: It really was astounding. They were claiming to have recovered DNA from animals which had died 20 million years before; not yet as old as the dinosaurs, but that's what a new team, including the Poinars, turned to next. And when they said what they had found, they caught the attention of the world. They had DNA from an insect older than T. Rex. So could Hollywood possibly have got it right?
GEORGE POINAR: We felt that bringing back an entire dinosaur was not in the realm of possibility, at this time.
DAVID GRIMALDI: Barraged with the common question, when are you going to clone extinct organisms, we constantly had to repeat ourselves: "We are not going to do that."
DAVID ATTENBOROUGH: But why not?
DAVID GRIMALDI: If DNA is indeed preserved in amber, it is so chopped up, so fragmentary, that it is impossible to reconstruct the entire genome and then insert it into some surrogate organism, and then have a complete resurrected extinct species out of that. That is absolutely impossible.
DAVID ATTENBOROUGH: As the blaze of publicity surrounding the film faded, so other scientists tried to extract DNA from amber insects. And their results, when they were published, were bad news for the Poinars and David Grimaldi. None of them had found even a trace of ancient DNA. But what went wrong?
DAVID GRIMALDI: What some of them found, in fact, were contaminant DNA sequences. And I have to admit, by that point, that I was pretty much convinced that the original reports of DNA sequences in amber were of contaminant DNA.
GEORGE POINAR: And some of the scientists that did make an attempt got all kinds of strange things. They would get fish DNA. Well, perhaps they had a tuna fish sandwich that day and were careless.
DAVID ATTENBOROUGH: Like most other researchers, David Grimaldi has changed his mind. But George Poinar is still confident that a few rare pieces of amber do contain DNA. And some insects certainly could have drunk the blood of dinosaurs.
These sandflies have been preserved in amber for 100 million years. Who knows what might be inside them?
And that is why amber fascinates me so much. It has brought us so many surprises. The prospect of it preserving DNA brought dinosaurs back, at least in our imaginations. And the creatures that traveled in it through time bring us vivid snapshots of the Caribbean forest as it was 20 million years ago. And my piece of Baltic amber, the first I ever owned, has preserved creatures with such perfection that they are still startlingly beautiful.
What a journey amber has taken me on! And it all came from a gift from a small girl over 60 years ago. I imagine Marianne and her father found my piece of amber by walking along a Baltic shore, just as thousands of people had done before them. Its magic may not extend to recreating a dinosaur, but, for me, amber remains a substance of wonder, a time machine that can show us exactly how some things looked tens of millions of years ago.
On NOVA's Jewel of the Earth Web site, use our interactive map to search for sources of amber around the world. Find it on PBS.org.
Educators and other educational institutions can order this or other NOVA programs, for $19.95 plus shipping and handling. Call WGBH Boston Video at 1-800-255-9424.
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Jewel of the Earth
PBS Airdate: February 14, 2006Go to the companion Web site
NARRATOR: Amber: its jewel-like beauty has held humans spellbound for thousands of years, but inside an even greater treasure glows.
DAVID ATTENBOROUGH: It's hard to imagine a more perfect time capsule than this. This little bee has been trapped in there for literally millions of years.
NARRATOR: Suspended in time, these tiny prisoners have tales to tell of a world that belonged to the dinosaurs, of enemies long extinct, of supercontinents that no longer exist. Now scientists can peer deeper into these time machines than they ever did before, opening the door to the unthinkable, bringing dinosaurs back to life.
DAVID GRIMALDI (American Museum of Natural History): I was astounded at the possibility of DNA being preserved.
ROBERTA POINAR (Oregon State University): Every once in a while, in your life, you witness something that's just too spectacular for words, and this was one of the times.
NARRATOR: Host David Attenborough takes you on a quest for amber. Jewel of the Earth, right now on NOVA.
Google is proud to support NOVA in the search for knowledge: Google.
Major funding for NOVA is provided by the Howard Hughes Medical Institute, serving society through biomedical research and science education: HHMI.
Major funding for NOVA is also provided by the Corporation for Public Broadcasting, and by PBS viewers like you. Thank you.
DAVID ATTENBOROUGH: There is a substance so strange and so beautiful that whenever people encountered it, they thought they had found something magical. And its magic is real, because this material has traveled through time, bringing with it passengers from the distant past that have wonderful tales to tell.
This extraordinary substance has fascinated me since I first held a piece, this piece, when I was 12. My first piece of amber arrived in a very unexpected way.
In 1938, during the build up to the Second World War, my parents helped some of the many children fleeing from Germany. They had left their families behind and were allowed to bring almost nothing with them. I remember one girl, in particular. Her name was Marianne. She was 12, about the same age as I was, and she came from a city on the Baltic coast where her father was a doctor.
He had given her one small but precious thing, as a sign of his thanks to whoever it was who was going to look after his daughter. And this is it. It felt surprisingly warm and light in my hand, but what made me fall in love with amber was what I discovered inside it. I found something miraculous.
There were insects preserved in astonishing detail. I burned with questions. What sort of world were they from? They must have lived a long time ago, but how long? Years later, my brother Richard would play a scientist in a movie which made amber famous the world over.
RICHARD ATTENBOROUGH (Actor/John Hammond in clip from "Jurassic Park"): Welcome to Jurassic Park.
DAVID ATTENBOROUGH: Richard's character extracted DNA from dinosaur's blood trapped in amber and, with it, brought dinosaurs back to life. Could that ever be done?
SAM NEILL (Actor/Dr. Alan Grant in clip from "Jurassic Park"): How did you do this?
RICHARD ATTENBOROUGH (Actor/John Hammond in clip from "Jurassic Park"): I'll show you.
DAVID ATTENBOROUGH: I started my journey with the amber time machine by taking Marianne's gift back to where it came from, to the shores of the Baltic Sea.
The amber comes from rocks on the seabed, some distance out from the coast, but people don't find it until it washes up on the shore. Little bits like this are quite common. Sometimes, if you are lucky, particularly after a storm, you can find bigger bits. Some even have barnacles still attached to them. People have been collecting such bits for thousands of years but had no idea how amber originated. Some said it was solidified sunshine, some that it was the tears of the gods.
Then, around the year 77 A.D., a great Roman naturalist, Pliny the Elder, conducted a simple experiment. He did this.
The smell? Unmistakable: pine resin.
Several types of plants, among them conifers, seal any wound inflicted by storms or insect attack, by producing a sticky resin which oozes out from them. And because it continues to gently flow around whatever it traps, it can preserve creatures in the finest detail. As the resin hardens around its captives, they become suspended in time.
Of course, many creatures are fossilized in rock, like this small flat fish, for example. It's a kind of ray. It was squashed, its soft parts decayed, even its little spines turned into rock.
But amber preserves creatures in a quite different fashion. When this little bee touched this drop of resin she was caught by its stickiness, and she was instantly and perfectly preserved in three dimensions. These eyes saw a world which existed long before mankind evolved. She scented flowers before the first human being ever smelled one. And I can even tell that she was working hard when she died, by the bundles of cargo on her hind legs.
It's hard to imagine a more perfect time capsule than this. This little bee has been trapped in there for, literally, millions of years.
Amber's ability to travel through time can take us back into more recent history, our history. Stonehenge is one of the earliest man-made structures in the world. These stones have been standing here for something like three and a half thousand years, and we know that, even then, the people who erected them treasured amber.
But they weren't the first. It was considered to be precious way back in the Stone Age, and this may be why. When you scrape its rough surface, with a flint blade, perhaps, you quickly reveal the wonderful golden color inside. It's quite magical.
Stone Age people also carved bone and stone in order to make tools, but amber was different. It seemed to have had no practical use, so they must have valued it for some other reason.
The carvings they made, around 10,000 years ago, give us an idea of how they viewed the world, and, in particular, which animals mattered most to them. Imagine the value of amber to a Stone Age hunter who believed that capturing an animal's spirit by carving it in amber made the animal itself easier to hunt.
The people who built the great stone circle at Stonehenge lived in the Bronze Age, several thousand years later, but they, too, treasured amber. None but the wealthiest of them could afford a material as rare as this.
Once, there were a thousand beads in this necklace. Over 3,000 years, their surfaces have become opaque and crumbly. But when they were new, and freshly polished, and glowing, it must have been a wondrous piece of jewelry.
One woman's grave contained a rather more mysterious object, a disc of amber, now browned with age, encircled by gold. It was certainly a remarkable piece of personal decoration, but maybe it had a rather deeper significance.
The sun is central to our understanding of Stonehenge. The monument may have been used as a solar calendar, and it may be that its builders treasured amber, because it captured the warmth and the light of the sun. It may or may not have been considered magical in prehistoric Britain, but it was most certainly rare, for it came from far away.
This is the Baltic city of Gdansk, in Poland. The jewelry worn by the people of Stonehenge, and buried with them, came from around here. It is evidence of one of the world's first long distance trade routes.
But what brought the big boom in amber was the rise of Imperial Rome. The Romans bought it for prestige. Amber carvings cost more than the best slaves, and even the emperor Nero treasured it. He decorated his amphitheaters with tons of it, to show how unbelievably wealthy he was.
So Baltic amber can take us back at least 10,000 years into our own past, but it reaches back much further than that.
To find out how far, I went to one of the Gdansk workshops where amber jewelry is made, to meet Elzbieta Sontag.
ELZBIETA SONTAG (University of Gdansk): ...very thin, it's most probably with inclusion inside.
DAVID ATTENBOROUGH: Elzbieta is a biologist who comes here to look for "inclusions," animals and plants trapped in the amber.
It takes a practiced eye to search through as much raw amber as this, and I was delighted to get a lesson from the expert.
How do I start? I mean, there are a million pieces, all right a thousand pieces. What...is there a particular color I should look for?
ELZBIETA SONTAG: Sometime color yes, because white and milky is without inclusion.
DAVID ATTENBOROUGH: Are they good?
ELZBIETA SONTAG: No.
DAVID ATTENBOROUGH: Oh. That's bad?
ELZBIETA SONTAG: It's bad.
DAVID ATTENBOROUGH: Okay, I'm not interested in that.
ELZBIETA SONTAG: Okay, I avoid it, that kind of color.
DAVID ATTENBOROUGH: So what do I...
ELZBIETA SONTAG: I'm looking for transparent.
DAVID ATTENBOROUGH: Would that one be any good?
ELZBIETA SONTAG: Yes. I think, yes. We can split it.
DAVID ATTENBOROUGH: Ah, really?
ELZBIETA SONTAG: Oh, yes.
DAVID ATTENBOROUGH: And...
ELZBIETA SONTAG: And may be something is inside.
DAVID ATTENBOROUGH: How many pieces do you look at before you find something?
ELZBIETA SONTAG: Oh, about 20.
DAVID ATTENBOROUGH: Twenty. Eleven...
ELZBIETA SONTAG: Not good, shape is not good.
DAVID ATTENBOROUGH: Why is it the wrong shape? Twelve.
ELZBIETA SONTAG: Next one...
DAVID ATTENBOROUGH: Thirteen...spit...there's a lot of bubbles. Fourteen...
ELZBIETA SONTAG: Wow! Oh, no. Maybe.
DAVID ATTENBOROUGH: Fifteen, nothing. Yes, I think so, 16. It's a mosquito.
ELZBIETA SONTAG: No mosquito, midges.
DAVID ATTENBOROUGH: Oh, but this is beautiful. The midge looks as though it took off from its twig only yesterday. But, amazingly, it has been frozen in flight for around 40 million years.
So what about the creatures in my piece? What exactly were they? I could see them clearly, for Elzbieta's microscope had a projection screen.
Oh, well that's an old friend, because it's quite big and it's near the surface, and I've known it for a long time. So it's a fly but what kind of a fly?
ELZBIETA SONTAG: It's a long-legged fly.
DAVID ATTENBOROUGH: A long-legged fly? And in what part of the forest do they live?
ELZBIETA SONTAG: Low on the forest. Sometimes sit on the bark.
DAVID ATTENBOROUGH: So the likelihood is, then, that this fly, and therefore this piece of amber, this gum, this resin, was low down on the tree.
ELZBIETA SONTAG: Yes, low down on the floor.
DAVID ATTENBOROUGH: Okay, what else is there?
With her powerful microscope, Elzbieta was exploring far deeper into my amber than I had been able to do, and there she found another fly, a fungus gnat. It must have died searching for rotten wood, for that is where it lays its eggs.
Then Elzbieta found an aphid and, right above it, an ant. Perhaps they had fallen together from a leaf where they were feeding. I think that's a fantastic picture. I mean, I...and it's deep in the amber. I know, because I've never seen it like this before.
But the last animal she found was the most surprising. Ah, what a monster! What is it?
ELZBIETA SONTAG: There is a mite.
DAVID ATTENBOROUGH: A mite.
ELZBIETA SONTAG: Yes, a very small monster.
DAVID ATTENBOROUGH: Yes. That's tiny though, isn't it? How big is that?
ELZBIETA SONTAG: That one? Half a millimeter.
DAVID ATTENBOROUGH: Half a millimeter.
I've never seen it before. So we've got a whole community—and we know that they all lived together because, because they all died together—in my one piece of amber. And that alone has given us a whole rounded picture of a tiny little ecosystem, at the bottom of a tree, 40 million years ago.
ELZBIETA SONTAG: Exactly.
DAVID ATTENBOROUGH: Amazing. Thank you very much.
It had taken me more than 60 years to find and identify all the animals inside my amber. And seeing them together had given me something more, a glimpse of their world.
By comparing many amber animals to modern forms, scientists like Elzbieta are sure that the forest they inhabited was a temperate one. But how broad a picture can these time travelers give us? Could it encompass a whole forest or even a whole continent?
Well, in the 1960s, on a Caribbean mountainside, science discovered a new source of amber which seemed perfectly suited to answer those questions. I had a chance to visit it 15 years ago. I hoped that for the first time, I, myself, might collect some amber.
Here in the Dominican Republic, amber is mined. And by dating the mudstones that contain it, we can tell that it is about 20 million years old, rather younger than Baltic amber.
Picking a piece of amber from the mudstones in which it has lain for so long was hugely exciting. I brought a small collection back home with me. So what kind of forest did this amber come from? Well thanks to some remarkable detective work, we can answer that question in amazing detail.
In this piece, there's a leaf from the plants that produced the amber. And this is what those plants looked like. They were giant bean trees. But what matters most about them is not what they looked like but where they grew. They were tropical.
Scientists had long imagined that the ancient tropical forests contained a vast diversity of life, but very few fossilized traces had ever been found, until they discovered these.
Dominican amber preserves such a huge variety of animals and plants, with such perfection, that it inspired two scientists, George and Roberta Poinar, to try something that had previously been thought impossible. In the same way that Elzbieta reconstructed the world around a single Baltic tree, they started to use these tiny fossils to bring a whole tropical forest back to life.
I had found a piece which contained a little bee. She must have been familiar with many of the plants in that forest, indeed she depended on them. So, based on the Poinar's findings, and with a little bit of amber magic, we can follow her back home.
This tiny flower shows that the amber trees were not the only giants reaching up into the forest canopy. It belonged to a sebo, whose great trunk is supported by wide buttress roots.
But the commonest flowers of all came from a different tree, the nazareno. It seems likely that these trees dominated the forest canopy. When one of these giants fell, it would have opened up a light gap, which other, faster-growing plants could fill, plants like palms.
And here are their flowers, confirming that palms were another key element of that forest.
So we have built up a picture of what part of the forest was like and even identified some of the flowers which might have tempted my bee. But I don't think she died collecting nectar.
She was searching the forest for something else. Remember those bundles on her back legs? They are clues to what she was after. She was collecting resin, and not just any resin, but resin from the amber trees themselves. And that was a very dangerous thing to do. She was a stingless bee, very skilled at handling resin. Even so, there was a real chance that while collecting it, a bee might get stuck. Stingless bees are among the most common animals trapped in Dominican amber. Why did they take the risk?
Resin is very valuable to these bees. Mixed with plant waxes and fibers, it makes a strong building material for their nests. But it also brings another benefit. It contains antibiotics which disinfect the wounds in the bark of the tree from which it oozes. By bringing it here, into the nests, the bees protect their developing young from infection.
So now we know exactly what this little bee was doing in that forest 20 million years ago. This piece of amber has not only trapped her body, it also caught her behavior. And we know from other pieces of amber, too, that she had enemies.
This is an assassin bug. It hunts stingless bees, and their addiction to resin makes it easy for it to find them. The bug can't move swiftly enough to snatch a bee from midair, but it's strong enough to pull off strands of resin. With these sticky gloves it can hold on to any bee which touches them. It's using resin to set a trap. Now the assassin stabs its dagger-like mouthparts into a weak point behind the bee's head and injects its saliva, paralyzing the bee. As she dies, she releases a pheromone, a scent calling for help, which normally rallies other bees to defend the nest, and that entices them into the assassin's reach.
But one assassin lost its grip and now lies in amber, together with its victim. Once small animals like this were in the resin's grip they were as doomed as flies on fly paper. But, even so, amber sometimes contains animals that, normally, would never go near it.
How can George Poinar explain his next discovery? It was an amber tadpole. It couldn't have come into contact with resin underwater, yet when he looked further, he found other pond animals: a young marsh beetle, even a diving beetle.
The challenge was to explain how they had found their way into a flow of resin on the trunk of a tree. This is a poison dart frog. She is only half the size of your thumb, and, remarkably, she is carrying a tadpole on her back. She moves in a very determined and purposeful way, and starts to climb a tree.
These are what she is looking for: plants that collect water, called tank bromeliads. No one has yet found a piece of a bromeliad in amber, but we know they were there because there are amber damselflies of a kind which today lays its eggs between the tightly packed leaves of bromeliads.
She's reached a branch. Her tadpole will soon have a nursery. She lowers her rear end into the bromeliad's pond.
Other animals also lived in these tiny ponds. Up here they may have been safe from predators but not, it seems, from resin. So bromeliads held tiny complete worlds high up above the ground, but, even so, they probably didn't contain enough food to sustain a fast growing tadpole. What, then, did it eat? Amazingly the piece of amber that held the tadpole also contained the answer.
Poison dart frogs are very attentive parents. Every few days the tadpole's mother climbs back up the tree to the bromeliad to care for her youngster. She's laying an egg. That's what the other object was in the amber. These eggs are sterile and don't grow into frogs, they are food. But occasionally these little worlds up in the branches were shattered. And at least one falling tadpole came to a sticky end.
Who would have thought that amber could reveal such intimate details of life in tiny ponds high up in such trees as these?
But what about the bigger animals of the forest? Amber surely can't tell us anything about the presence or absence of these. Or can it?
Remarkably, amber does contain evidence of one such creature, thanks to some very oddly shaped seeds. These are the seeds of a kind of bamboo. The hooks on them get stuck in the hairs of animals so that the seeds travel with them and so are dispersed. But what sort of animals carried these seeds? Well, sometimes such seeds have hairs still attached to them, and the only animals with hairs are mammals.
There were certainly a number of mammals around 20 million years ago, but can these hairs help us to be a little more specific as to which mammals were here? They can.
The shape of the scales on the surface of hairs varies, and George Poinar used them to narrow down the possibilities. They came from some kind of carnivore.
It seems there were big cats in the ancient forest. Perhaps they even hunted the ancestors of modern coatis. So that's one more animal that I know that lived in that forest, but what about organisms for which there is not even a hair to serve as evidence?
Amber really is astonishing, because, as well as carrying animals' bodies through time, it can bring clues to their relationships. And that is what makes me certain that the forest contained enormous fig trees like this, although no trace of such a tree has yet been found in amber.
Let me explain. George Poinar found the crucial evidence. Exhibit A: a minute wasp. This wasp proves that the forest had figs, but to find out what makes it such a conclusive witness, we need to see what goes on today, inside the figs themselves. Although they look like fruit, figs are really containers for the tree's flowers and its developing seeds. But some also house wasps. Fig wasps spend almost all their lives inside figs, which are sealed so nothing but a fig wasp can collect their pollen. And that is how the wasps repay the fig trees for providing their nursery, by distributing their pollen.
These two organisms have come to rely on each other so closely that it's impossible for one to exist without the other. That is why a single wasp can guarantee that the forest contained fig trees. The partnership between figs and wasps is one of the most intimate in the whole of nature.
But that piece of amber had something else to reveal, something that was rather more sinister. The rear end of the wasp is surrounded by minute nematode worms. As the wasps emerge inside a fig, so do these nematodes. Each has just a few minutes to find a wasp and burrow into its body before it leaves the fig. But these are not conventional parasites. The only thing they will take from the wasps is a free ride to the next fig. Only amber could have preserved such minute details and, with them, revealed an extraordinary fact.
The relationship between the forest's fig trees, their wasps and worms, that we know today, clearly existed 20 million years ago. Amber, again and again, demonstrates this constancy.
Take this, for example. It looks like a death scene, a scale insect in the jaws of a predatory ant. But the truth is very different. Scale insects drink the stress, anxiety or panic of pods, but this takes time. Predators would soon pick them off, if it wasn't for the teams of ant bodyguards that protect them. And in exchange, the ants receive a share of the sap. By providing ants with food that they can't otherwise reach, the scale insects have made themselves indispensable. This relationship was so important that, far from eating her captive, this queen ant was gently carrying it away, so it would set up a new colony beside her own. And for 20 million years neither partner has had any reason to change.
What does this astonishing absence of change imply? If conditions had altered radically, many of these complex relationships would have disappeared. So their presence tells us that tropical forests must have existed, largely unchanged, for at least 20 million years.
But now George Poinar has traveled back even further in time. One of his latest finds in Dominican amber takes us back not just 20 million years, but 150 million, for it has implications about the Earth's geological history. And this startling new evidence comes from a single ant.
I have come across its modern relatives myself, and their behavior can tell us something unexpected about the Dominican amber forest. They are honeypot ants whose workers have become jars in which the colony stores honey to help it through times when liquid and nectar are scarce in the dry season.
So this amber honeypot ant suggests that the ancient forest also had a dry season. And if the modern ants are anything to go by, then it lasted around three to four months.
So, now, amber can tell us how often it rained 20 million years ago. But it is also evidence of an event that occurred even further back in time, because the living honeypot ants I found don't occur in the Dominican Republic or even in South America; they live in Australia.
So these little ants are evidence not only of climate, but the fact that once Australia and South America were joined together in one supercontinent. Who would have thought a single ant could tell us so much?
The amber time machine could hardly illuminate a more global event than the drift of continents, but it can also take us to the opposite extreme. What surprises might we find inside an amber animal?
Dr. David Grimaldi, of the American Museum of Natural History, is especially interested in lizards. These Anolis lizards are very territorial and the males take great risks to secure a patch of bark for themselves. They spend a lot of time displaying aggressively to one another, doing press-ups and erecting their throat flaps. And sometimes they fall. A few have achieved fame and immortality in amber, but such specimens are very rare, and not surprisingly. A lizard should be strong enough to unstick itself from a flow of resin. But some did not, and that puzzled David Grimaldi.
He wondered whether they could be as well-preserved inside as they were outside. Could he actually look inside an amber lizard? He turned to the latest high tech scanners.
DAVID GRIMALDI: These are scans that use very high intensity x-rays that are too high for medical purposes, and we have incredible detail in any view that we want. This scan of a gecko's head shows the finest details of its skull and even its teeth. Amber's preservation is clearly more than skin deep but nothing in this scan could explain why this gecko was trapped.
DAVID ATTENBOROUGH: So David Grimaldi turned to another gecko and looked at its whole body, this time with conventional x-rays.
DAVID GRIMALDI: The x-ray revealed that the bones were beautifully preserved. Bones of the skull, delicate little toe bones, bones of the leg and even individual vertebrae are revealed. But, from the jumble of bones, it is clear that the gecko's back was broken. It had probably been picked up and dropped, perhaps by a bird of prey. It didn't escape from the resin because, when it hit it, it was already dead.
DAVID ATTENBOROUGH: As researchers started finding even smaller internal details preserved by amber, they began to ask themselves something almost unthinkable. Could amber have preserved molecular structures inside an animal? Perhaps even its DNA? Some people even imagined that such DNA could bring monsters back to life. And look where that got us. But there are no remains of dinosaurs in amber. Surely their DNA is beyond our reach.
The Poinars dared to wonder if that was so. The story begins 20 years ago, when Roberta first focused an electron microscope on an amber animal. Inside a fungus gnat, like the one in my piece of Baltic amber, she discovered something quite amazing.
ROBERTA POINAR: It's like a miracle. Every once in a while, in your life, you witness something that's just too spectacular for words, and this was one of the times.
DAVID ATTENBOROUGH: The Poinars had found 40-million-year-old cells, and more than that, even the minute structures inside the cells were clear to see.
GEORGE POINAR (Oregon State University): We were kind of flabbergasted that it was possible to have such a degree of preservation after such a long time.
ROBERTA POINAR: And so I, you know, zoomed on up to a higher magnification and just was amazed to see that there were nuclei with bits of chromatin in the nucleus. And that is the step that led us to believe that DNA was there, in the cell, and could, perhaps, be pulled out and looked at.
DAVID ATTENBOROUGH: It was an astonishing discovery. The prospect of finding such ancient DNA electrified the scientific community. And Hollywood wasn't far behind. The storyline of Jurassic Park is very ingenious. My brother, who played the scientist, didn't actually need to find bits of dinosaur in amber. Nature had already extracted their DNA in blood cells and preserved it inside an amber mosquito. But that's pure fiction isn't it?
DAVID GRIMALDI: Surely it is impossible to recover DNA from any animal which lived in the distant past.
DAVID ATTENBOROUGH: Well, two teams set out to attempt exactly that. One of them included David Grimaldi. The other was set up by the Poinars. Both knew that their only chance of finding DNA was in the best-preserved animals, so the Poinars chose to use my favorites, some stingless bees, while the other team decided to work on an amber termite.
DAVID GRIMALDI: We had no expectations—at least I didn't—when we did the study. We did the extractions. We tried it. Several of the extractions were unsuccessful.
DAVID ATTENBOROUGH: But then both teams struck gold. Tissue extracted from the Poinar's bees tested positive for DNA, and David Grimaldi got the same result from the termite.
DAVID GRIMALDI: Our first reaction, particularly mine, was really disbelief. I was astounded at the possibility of DNA being preserved.
DAVID ATTENBOROUGH: It really was astounding. They were claiming to have recovered DNA from animals which had died 20 million years before; not yet as old as the dinosaurs, but that's what a new team, including the Poinars, turned to next. And when they said what they had found, they caught the attention of the world. They had DNA from an insect older than T. Rex. So could Hollywood possibly have got it right?
GEORGE POINAR: We felt that bringing back an entire dinosaur was not in the realm of possibility, at this time.
DAVID GRIMALDI: Barraged with the common question, when are you going to clone extinct organisms, we constantly had to repeat ourselves: "We are not going to do that."
DAVID ATTENBOROUGH: But why not?
DAVID GRIMALDI: If DNA is indeed preserved in amber, it is so chopped up, so fragmentary, that it is impossible to reconstruct the entire genome and then insert it into some surrogate organism, and then have a complete resurrected extinct species out of that. That is absolutely impossible.
DAVID ATTENBOROUGH: As the blaze of publicity surrounding the film faded, so other scientists tried to extract DNA from amber insects. And their results, when they were published, were bad news for the Poinars and David Grimaldi. None of them had found even a trace of ancient DNA. But what went wrong?
DAVID GRIMALDI: What some of them found, in fact, were contaminant DNA sequences. And I have to admit, by that point, that I was pretty much convinced that the original reports of DNA sequences in amber were of contaminant DNA.
GEORGE POINAR: And some of the scientists that did make an attempt got all kinds of strange things. They would get fish DNA. Well, perhaps they had a tuna fish sandwich that day and were careless.
DAVID ATTENBOROUGH: Like most other researchers, David Grimaldi has changed his mind. But George Poinar is still confident that a few rare pieces of amber do contain DNA. And some insects certainly could have drunk the blood of dinosaurs.
These sandflies have been preserved in amber for 100 million years. Who knows what might be inside them?
And that is why amber fascinates me so much. It has brought us so many surprises. The prospect of it preserving DNA brought dinosaurs back, at least in our imaginations. And the creatures that traveled in it through time bring us vivid snapshots of the Caribbean forest as it was 20 million years ago. And my piece of Baltic amber, the first I ever owned, has preserved creatures with such perfection that they are still startlingly beautiful.
What a journey amber has taken me on! And it all came from a gift from a small girl over 60 years ago. I imagine Marianne and her father found my piece of amber by walking along a Baltic shore, just as thousands of people had done before them. Its magic may not extend to recreating a dinosaur, but, for me, amber remains a substance of wonder, a time machine that can show us exactly how some things looked tens of millions of years ago.
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