Hi, I'm Dacher Keltner. You're listening to a special series from our team at The Science of Happiness all about the science of love. Hosted by award-winning actress, author, and activist Gina Davis, we explore what the research tells us about the many different kinds of love in our lives. Enjoy the show. I want to be loved by you. What is love? For centuries, philosophers, artists, and theologians have tried to define it. Scientists are newer to the task. Love is complex, messy, and hard to measure. But that hasn't stopped them from trying. And they're beginning to explore just how expansive love can truly be, a biological, cultural, and social phenomenon. Hi, I'm Gina Davis, and this is The Science of Love by the Science of Happiness podcast and PRX. Over the next three episodes of The Science of Happiness, we'll hear emerging science on why we love, how it develops, and how it sustains us across many kinds of relationships, beyond romance, into our friendships, our families, and even our non-human companions. The Science of Love, after this break. Welcome to The Science of Love, a special by the Science of Happiness podcast. I'm Gina Davis. Love isn't simply a feeling. Research suggests it's a core biological drive, essential for both our happiness and our survival. And we know that it shows up in countless ways, like with the love that shapes us from the start. The love between a parent and a child is very, very ancient. And romantic love. I get shaky knees when I'm with this person. I'm scared to say the wrong thing. Our friendships. One study found that when people thought friendship was something that happened without effort, they were lonelier five years later. The deep connection we can feel towards animals and nature and the love we feel for our wider communities. It's that connection and that feeling and that love of humanity generally which leads us to want to help people who are different from us. Over the next three weeks, we'll be traveling across the country from Los Angeles to Bloomington, Indiana, to St. Louis, Missouri, to New York City, to find out how scientists are beginning to uncover answers to age-old questions about love. We begin in outer space. Can you hear that? The heartbeat. That's the heartbeat of a woman in love. Recorded in 1977, it's part of a collection of sounds and images on a record that NASA affixed on their Voyager space probes. The hope was that if any extraterrestrials came across it, they might be able to decode the message and understand at least a little bit about what life is like on Earth. It tells the story of our planet through sounds consisting of the world's music, images of life on Earth, greetings in some 59 human languages. Hello from the children of planet Earth. The greetings of the humpback whales. And crickets and more. These interstellar messages also included recordings of human biorhythms, like brainwaves, the sound of laughter, and a heartbeat. Specifically, Ann Druyan's heartbeat. It was my great honor to be the creative director of the Voyager Interstellar Message Project. Durian worked on the project with someone whose name you might recognize. The cosmos is full beyond measure of elegant truths, of exquisite interrelationships. Astronomer Carl Sagan. And over the course of the project, she and Sagan fell deeply in love. During the making of the record, when we spoke on the phone long distance, and Carl told me how he felt and I told him how I felt, that felt like a eureka moment. Like Carl and I had made a scientific discovery. And with every heartbeat since, I have to say, it was true. When it came time to assemble the golden record, Drugand suggested recording a sample of human biorhythms while she meditated. on the history of Earth, the history of humanity, and the current predicaments that civilization was finding itself in. Towards the end, her meditation morphed into a personal one, a meditation on love. It began with the love that we feel for our children, and our children for their parents and grandparents and guardians, and all the different kinds of love that adults feel. And then, you know, Carl Sagan and I had just fallen madly in love So I had to confide in the extraterrestrials that I had discovered what that feeling was in its greatest meaning and depth. That recording of Drugin's heartbeat during her 1977 love meditation is still traveling through interstellar space, some 15 billion miles away from Earth. It feels amazing. It comforts me. I think about it all the time. For me, love and science are deeply, inextricably related. You know, because people think that the dispassion that science requires in the gathering of data and its analysis is the same as being unmoved by it. But demystifying love does not make it less. The more you know about it, the greater it is. Love is etched onto the most distant human objects in our universe and it embedded in our lives everywhere on Earth But why do we love We love for survival. From the moment we're born through the rest of our lives, we need other people. Social psychologist Sarah Eljo. For growth, for learning, and for thriving. Love is intangible. Neuroscientist Daniel Levitin. It's not logical. It's not limited to things that we can describe in a three- or four-dimensional universe. I suppose I could give you an evolutionary theory as to why we love, which is for group cohesion, because that improves our chances of survival. Social and environmental scientist Jessica Ayes. But that feels so flat in the face of how majestic love is. In a way, it's a form of biological bribery. Evolutionary anthropologist Anna Machen. Love evolved to make sure the genes carry on down the generations. The people we love can shape our health in surprising ways, right down to the microbes in our body. Reporter Mandy Wynn met a scientist studying how our relationships leave a biological trace. On a chilly winter morning, I met up with my friend Kelso at a diner in Brooklyn, New York. Hi. Hello. How's it going? Good. We came for one thing. Fluffy pancakes. Silver dollar pancakes. I don't even know what that means. Banana or apple. I met Kelso three years ago, and we see each other pretty often. Sometimes we watch movies. Recently, we've been making s'mores in their backyard. We're usually sharing food. Isn't that so good? Okay, wait, wait. Me, me, me. But we may also be sharing something else. Yeah, we are swapping some microbes, right? Yeah. There are trillions of fungi and bacteria and microbes that call our bodies home. And they're vital to our health, especially those in our gut microbiome. They help us digest food, regulate our immune systems, and have even been linked to conditions from diabetes to depression. I mean, especially like eating these pancakes. Breathing in each other's faces. Yeah, because we're like a foot away from each other. It's like an express highway. Diet or genetics account for a lot of what our microbiomes look like. But recently, scientists have been looking at how our relationships might be changing the microbes in us too. How many of those stick around? Do we know? Studies show that mothers pass microbes to their infants. And spouses who live together tend to have similar gut microbiomes over time, as do friends. We mapped these villages and we know who is interacting with whom. we know exactly the kind of relationship these individuals have. That's Francesco Baggini. He's a computational biologist at Yale. He recently conducted a study in Honduras to see how people's microbiomes compared to their loved ones and friends. His team collected saliva and stool samples from almost 2,000 Hondurans, samples that were sent to his lab at Yale, where Baggini and I met. Yeah, so right now we are heading to our wet lab. The samples are in freezers kept at negative 112 Fahrenheit to keep the cell stable long term. We have racks of boxes. To avoid frostbite, Baghini takes out a box of samples wearing a pair of big bulky mittens. Yeah, thanks for getting that out from me. That was like a whole thing. We can see around 100 different species of bacteria. That's millions and millions of bacterial cells. When Baghini analyzed the data, he saw that the families and couples living together shared the highest amount of microbes. But he also found a strong similarity between friends, much more than that shared between strangers. So we are able to predict the existence of relationship based on how many bacteria two individuals share with each other. And the more time people spent together, and especially the more meals they shared, the more their microbiomes converged. Two years later, Baghini checked again. Friends who'd stayed close had grown even more alike. It wasn't just about living in the same village or having similar diets. It was about the relationship itself. The fact that friendship and loving relationships can actually affect your microbiome is remarkable. That's Ilana Brito, a biomedical engineering professor at Cornell University and a co-author of the study. I think one of the things that it brings up, which is intriguing, is what is the impact of all of this sharing that you do with your friends and your family? If the microbiome plays such a huge role in our health, and we might be able to spread our microbiomes, that comes with the risk of spreading pathogens and disease. But most of the microbes exchanged in the study weren't actively making people sick. They were the kinds that live peacefully in our guts, the ones that might be regulating our overall health. They serve protective effects for our bodies. And so you can imagine that by sharing these organisms, you're providing that protection for the people around you. And the same microbes didn't just swap between friends, but extended to friends of friends. They could see the microbial similarities in entire groups of people. And so exposure to different people and intimate interactions might be beneficial for all of us. Just by spending time with our friends and loved ones, we change each other. Being friends with someone for a long time, being married to someone, sharing a household with someone, those things leave their mark on your microbiome and your biology. Back at the cafe in Brooklyn, Kelso and I finish up the rest of our pancakes and talk about what we're going to do next time we see each other. Or we could do another movie night, a bonfire. At this rate, I wouldn't be surprised if our microbiomes become more and more similar. We already share friends, hobbies, pancakes. What's a few million microbes? Thanks for your microbes, Mandy. You're welcome. You're welcome. The first person we share millions of microbes with is our mothers when we born Mothers carry cells from their biological children cells that cross the placenta during pregnancy. Likewise, children carry cells transferred to them in the womb from their mothers, and sometimes their maternal grandmothers and older siblings. And of course, we share more than microbes. The love between a parent and a child, particularly a mother and a child, is very, very ancient. That's evolutionary anthropologist Anna Machen again. She studies the evolution of love. That was probably the first love. We can tell that partly by the fact that a high degree of the activations in maternal love are within the core of the brain, in the limbic area of the brain, which is the ancient bit of the brain. And that little set of biological bribery at that point was really to make sure that mum stuck around and looked after what became increasingly a really dependent baby. I mean, human babies are arguably some of the most dependent babies on Earth. Before children even understand words, parents find ways to connect with them through touch, rhythm, and song. That's in part because when we hear the same music together, our brainwaves can synchronize both to the music and to each other. We'll learn about how music can strengthen love after this break. Hey, I'm Dr. Maya Shunker. I host a podcast called A Slight Change of Plans that combines behavioral science and storytelling to help us navigate the big changes in our lives. I get so choked up because I feel like your show And the conversations are what the world needs, encouraging, empowering, counter-programming that acts like a lighthouse when the world feels dark. Listen to A Slight Change of Plans wherever you get your podcasts. Welcome back to The Science of Happiness. I'm Gina Davis. Lullabies seem simple, one of the most basic forms of music, yet their effects are more profound than we might think. Research suggests that lullabies speak a universal human language, one with deep evolutionary roots. Shuka Kalantari reports on how lullabies, across cultures, help caregivers bond with their babies. I trust you. You know what to do Alexis Cariello wrote this lullaby for her son, Nico, in the middle of the COVID pandemic. She was pregnant at the time and struggling with severe perinatal depression and anxiety. The way that it manifested was very much disconnected from my body, yet I felt prisoner to it at the same time. Cariello's therapist connected her with a group at Carnegie Hall who helped expecting parents compose lullabies for their babies. She would hold her belly and sing to him to feel more connected. To hold and be help, I trust you. The process allowed me to kind of tap into the love that I was feeling because up to that point, I had just been feeling anxiety and sort of dread and like wishing time away. For you. Researchers found that when women with high-risk pregnancies spent just 20 minutes a day listening to lullabies and gently holding their bellies, they felt less anxious and more connected to their babies. It's universal. So all mothers instinctively sing to their infants, and they instinctively sing across cultures songs that have very similar features. Daniel Levitin is a neuroscientist and musician. The mother uses a soft voice, not a loud one. She uses small stepwise motion or occasional leaps, but slow tempo. If there's a leap, it always comes down again. Rock-a-bye, baby. I went up, now I'm going down on the treetop. When the wind blows, right? Infants are learning what their mother's voice sounds like so that in the dark, when they can't see one another, the mother can still soothe the infant. Researchers at Harvard's Music Lab have collected the sounds of men and women singing lullabies to their babies from all over the world. Ho Ho Uattane, Ho Ho Uattane Medimba Nayana Kani So you'll see the cultures range from like the Arctic, subarctic region all the way to Polynesia, Central America. That's Constance Bainbridge. She co-authored a Harvard study looking at how babies respond to lullabies from different cultures and foreign languages. When the babies heard the music, they relaxed. Their heart rate slowed and their brain activity calmed, regardless of the culture or language the lullabies came from. We also found that age didn't matter for the infants, so whether they were 2 months old or 14 months old, they had similar relaxation effects. And maybe you would think that with more exposure to music, having lived a little bit longer, there might be more of an effect, But the fact that even those really young infants had that similar effect is extra evidence that this might be something innate. After Cariello's son was born, she would sing him the lullaby she wrote every single night. I trust you, you know. Five years later she sitting with Nico on the floor of their Brooklyn apartment playing with toys He tells me he adores music And every night before bed there only one song he wants to hear His mama's lullaby. Gentle, soothing, and made with love. And sometimes, Nico sings along. Always remember, you can be tender. Give and receive and lead with. You can be open. I'm Shuka Kalantari, reporting from Brooklyn, New York. You can be broken. You can be free. Our first love may be our parents, but our first crush can introduce us to a whole new world of feelings and sensations. Butterflies in the stomach every time you see the person, a racing heart, sweaty palms. These intense, often overwhelming feelings have inspired countless songs that compare romantic love to substance addiction. But is it true? Are we really addicted to our lovers? This is a pet peeve that I have. they will provide a hypothesis that sounds very plausible. You are addicted to your beloved, and then if they break up with you, you go through withdrawal. And yes, that all sounds very plausible, but we need to actually get the scientific evidence. That's psychologist Sandra Langeslag. Reporter Mandy Wynn visited her lab at University of Missouri, St. Louis, to learn more. Hi. Come on in. So this is the testing room. This one sits. Inside psychologist Sandra Lageslag's lab, scientists are doing these experiments to see how love and addiction to a substance compare on a few levels. How they affect our attention, our craving, how pleasant we find them, and how alert they make us feel. We're testing participants that are both in love and addicted to something so that we can really, in a single person, see how the two compare. And the addiction of interest here? Vaping. Some research suggests that an addiction to a nicotine vape manifests in the brain similar to stronger drugs like cocaine. Do you vape? Are you in love? Are you in a relationship? And I was like, well, check, check. Okay, tell me more. That's Jessica. She took part in Langaslag's study and joined us at the lab to demonstrate how the experiment was done. So Jessica, you want to have a seat here? Let me get my supplies. Jessica sits in front of a computer, and Langaslag brings over a cap for her to put on. Slide the cap down. It's an EEG cap. It sort of looks like a swim cap with a lot of tiny holes in it. So here I have the electrodes. I'm going to click them in each of the holes. Our brains generate electrical signals, and the electrodes can pick that up. With a millisecond precision, so you can see in real time stuff that's happening in the brain. Once the cap's on, LangusLang sets up a slideshow on the computer. It cycles through pictures of Jessica's husband, strangers vaping, and strangers doing nothing. Your task is just to pay attention to the pictures? Okay. When people look at photos of their loved ones or something that reminds them of their addiction, parts of their brain usually snap to attention without them realizing. Langislai can measure attention by analyzing Jessica's brain signals, seeing what photos she reacts to the quickest and with the most focus. There's always a zillion things going on around us, but we can only focus on a few things at a time. Her participants weren't newly in love. Some were married, like Jessica, or lived with their partners for years. And most of them were past this early infatuation stage. So it wouldn't have been surprising if the measures for love came out weaker than for addiction. But that wasn't the case. On everything that we measure, people score higher for their beloved than for the vape. And so across the board, love seems even more intense than vaping addiction. Langis Lag says it's too early to say if love is actually an addiction. Her study is just one data point. We need more studies looking at other kinds of drugs and testing different measurements. But acknowledging just how intense love can feel is an important first step. I'm Manning Nguyen, reporting from St. Louis, Missouri. Once we fall in love, keeping the spark alive takes some effort. The idea really is to have these points of connection between people so that they can have a ritual that allows them to connect emotionally so they don't have parallel lives. We explore what the scientific literature tells us about how to keep love alive, plus the love we feel for our friends, our families, and our four-legged companions. Join me, Gina Davis, next week for another special episode of The Science of Happiness, all about the science of love. Thank you for exploring these many forms of love with us. This special is dedicated to the loving memory of radio producer Ben Manilla. The Science of Love is a production of the Science of Happiness podcast at UC Berkeley's Greater Good Science Center. Our executive producer and editor is Shuga Kalantari. Our senior producer and co-editor is Kate Parkinson-Morgan. Sound design and production by Jenny Cataldo of Accompany Studios. Our reporters are Troop Nguyen and Mandy Nguyen. Associate producers are Emily Brower and Tarani Kakar, fact-checked by Dr. Eli Sussman. Funding for this special was provided by the John Templeton Foundation as part of the Greater Good Science Center's Spreading Love Through the Media Initiative. I'm Gina Davis. I hope your day is filled with love. From PRX.
