When twin brothers Trevor and Kyle Ritland were children, their father — a biologist — would tell them stories about a mythical creature that lived high in the misty mountains of Costa Rica: the golden toad. The toad was elusive, he told them — but for a few weeks every spring, hundreds of them would emerge from the shadows to mate, lighting up the dense forest like brilliant spots of fire. Until one day, the golden toad vanished — never to be seen again.

It’s mysteries like these that have drawn scores of researchers out of their labs and into the wild — tugging them to explore, to climb distant mountains, to venture into faraway forests and discover or rediscover a creature, a place, some new clue.

On this encore episode, we hear stories of those adventures. We talk with Trevor and Kyle about their quest to find out what happened to the golden toad — and what they ultimately discovered. We hear the epic tale of writer Kim Frank’s travels to India in search of wild Asian elephants. And we talk with conservation ecologist Ryan Almeida about how the global wildlife trade is affecting certain species and their habitats.

At the best of times, alcohol makes us feel great — relaxed and gregarious, warm and fuzzy, happy and confident. But at the worst of times, it can morph into a serious problem, damaging our relationships, our health, and our lives as a whole. On this encore episode, we explore our relationship with alcohol. Why we consume it, how it affects us, and when it’s time to quit.

We talk with surgeon and recovering alcoholic Charles Knowles about how booze affects our brains and health, and what finally pushed him to give up alcohol for good; we hear about a trend known as “California sober,” and why so many people are embracing it; and we find out how zero-proof cocktail bars are helping some people socialize without the booze.

• Charles Knowles was barely a teen when he discovered the power of alcohol to transform him from a shy outsider into the life of the party. But as he got older, and sank deeper into drinking, alcohol stopped being fun — and started affecting his health and his life. We talk with Knowles,  a surgeon and physician, about what makes some people more vulnerable to problematic drinking, how alcohol affects our brains, and how his life changed once he stopped drinking. Knowles’ book is “Why We Drink Too Much: The Impact of Alcohol on Our Bodies and Culture.”

• For a lot of former drinkers, “sobriety” means total abstinence — no alcohol, or any other substances that produce a similar buzz. But recently, a new, more permissive version of sobriety has been gaining popularity: “California sober.” It involves embracing cannabis and psychedelics as a means of avoiding alcohol and hard drugs. Reporter Andrew Stelzer tracks the origins of this phenomenon, why some people find it helpful, and what researchers have to say about it.

• One of the hardest parts about sobriety for a lot of people is dealing with the social impact. Not only is alcohol a social lubricant — it’s often at the center of social events themselves. But recently, some entrepreneurs have been creating alternatives in the form of zero-proof cocktail bars. Pulse reporter Alan Yu visits Philadelphia’s Bar Palmina to find out who goes there, and why.

Two hundred and fifty years ago, Philadelphia was not just the center of political revolution, but a hub of scientific discovery. For America’s founders, science was more than a pastime — it was a way of understanding the world and the natural laws that shaped it. On this episode, we explore how science and innovation helped give birth to a new nation.

• We visit the American Philosophical Society in Philadelphia to explore how tracking the transit of Venus in 1769 became a major success for astronomers in the colonies, one that put American science on the map. We’ll also hear about efforts to find the exact location of the observatory that once stood near Independence Hall — the place some people say was the location where the Declaration of Independence was read out loud for the first time.

• The first sentence of the Declaration of Independence cites, “Laws of Nature and of Nature's God,” but what exactly does that mean? Caroline Winterer, Professor of History and American Studies at Stanford University joins us to discuss the ideas that allowed the Founders to bridge the gap between physical science and political governance, effectively inventing our modern concepts of society and inalienable rights.

• We dive into the story of the "Turtle," the first submarine used in combat which was invented during the Revolutionary War. Reporter Alan Yu explains the many innovations contained in this small vessel, and its daring first mission. Then Host Maiken Scott travels to The International Spy Museum in Washington, D.C., to see a replica of the craft.

• We head into the kitchen with three prominent Black Philadelphia chefs, Omar Tate, Angie Brown, and Shola Olunloyo, to reconstruct an iconic dish that fueled the revolution: Philadelphia pepper pot soup. Reporter Justin Kramon tells the story of this dish, and how people are keeping its memory alive.

On this episode, we explore the lingering effects of medical crises, both physical and emotional, and what true healing really means. We hear about one doctor’s journey to reconnecting with her body — and her pain — after nearly dying, what researchers are learning about medical trauma, and how a traumatic brain injury transformed the lives and marriage of a couple.

We often talk about the biological and emotional transformation of motherhood, but what happens to men’s brains when they become fathers?

On this episode, host Maiken Scott chats with psychologist and researcher Darby Saxbe to explore her new book, “Dad Brain: The New Science of Fatherhood and How It Shapes Men’s Lives.”

While the "dad bod" is a common trope, Saxbe’s research reveals that the changes go much deeper. Drawing on longitudinal studies, she explains how fatherhood triggers a biological reorganization — including measurable changes in brain volume within the social cognition network and dynamic shifts in hormones like testosterone and prolactin. Far from being "damage," these changes are an adaptive process, streamlining the brain to help fathers process social information and bond with their children.

Music can transport us to a different time and place — but how does that happen? We explore how music affects our brains — from its ability to tap into our memories and imaginations, to “musical daydreaming” and how it helps us understand both the world and ourselves. We also discuss the therapeutic power of music.

On this episode, we look at the intersection of health, medicine, and the law. We explore how the upcoming rescheduling of marijuana may impact research on the drug, hear the story of a doctor who faced manslaughter charges in the 1970s for providing an abortion, and learn about legislation that some states are using to try and keep private equity out of medicine.

Think about the last time you were really happy — where were you? What were you doing? Who were you with? And, most importantly, how can you recreate that feeling?

Happiness can feel like lightning in a bottle — beautiful in the moment, but hard to find and harder yet to sustain. So what is it that makes for a happy life? And how do we engineer our lives for greater contentment, fulfillment, and joy?

On this encore episode: the science of happiness and how we can experience more of it every day. We talk with psychologist Eric Zillmer about why certain places bring us joy, and how to engineer happiness in our lives. We hear about one reporter’s experiment to bring more moments of serendipity in her life. And, writer Daniel Coyle explains why community is at the heart of what it means to flourish.

• Drexel University psychologist Eric Zillmer created a “happiness map” of Philadelphia with the help of his students. He says it holds greater lessons on why certain places bring us joy, and how we can reverse-engineer happiness into our days. Zillmer directs the happiness lab at Drexel University.

• Writer Daniel Coyle built his career on exploring what it is that makes people successful — but when both of his parents died a few years ago, Coyle found himself unmoored, questioning what makes for a happy and meaningful life. The resulting journey led to his newest book, “Flourish: The Art of Building Meaning, Joy, and Fulfillment.” We talk with Coyle why he says community is at the heart of flourishing, how to create the right conditions for happiness, and why he says life isn’t a treasure hunt — it’s the process of treasure creation.

On this episode, we explore the world of color — from how we perceive it, to our efforts to describe and differentiate its many shades. We talk with a lexicographer about efforts to standardize synthetic colors, and how we describe them, and investigate how we know that the colors we see are the same as the ones everyone else sees.

When disaster strikes and the chips are down, who makes it out alive? On this episode, we explore what it takes to survive a crisis. We hear the incredible story of a 17-year-old girl, who after surviving a plane crash, faced a harrowing journey though the Amazon to safety, why some people experience hallucinations when facing death, and how we’re wired to behave in emergencies.