In 50 episodes, we’re going to explore biology—the science of life. Dr. Samuel Ramsey will guide you through life’s vast interconnectedness, telling lesser-known stories of biologists along the way. We’ll discover how evolution, genetics, ecology, and cell and organismal biology deepen our knowledge of every living thing: including ourselves.

Season 2 Episode 1 - Introduction to Biology

Biology is the study of life—a four-letter word that connects you to 4 billion years worth of family tree. The word “life” can be tricky to define, but a shared set of characteristics helps biologists identify living things. In this episode of Crash Course Biology, you’ll learn how all of life is connected, and why studying biology can help us better understand ourselves and our relationship to all living things. Air Date : 6th-Jun-2023  Read More

Season 2 Episode 2 - The Scientific Method

Science offers a way of discovering and understanding the world around us, driven by questions and tested with evidence. And it’s a twisty-turny team effort— you won’t find many lone geniuses out there, or straight lines from hypothesis to conclusion. In this episode of Crash Course Biology, we’ll talk about the big picture of how scientific progress is made, from peer review to mathematical models, with some exploding eggs along the way. Air Date : 13th-Jun-2023  Read More

Season 2 Episode 3 - What Biologists Do

A biologist’s natural habitat is anywhere questions about life are being asked—whether the subject is a nematode or a narwhal, a single cell, or a whole ecosystem. In this episode of Crash Course Biology, we’re flipping the microscope around to show how biologists’ work goes down. Along the way, we’ll learn why zebrafish and fruit flies are some of biology’s next top models. Air Date : 27th-Jun-2023  Read More

Season 2 Episode 4 - How Life is Organized

Here on Earth, life is dizzyingly diverse—but it’s also surprisingly organized. A sense of order structures life and its processes, from the tiniest cell to the total sum of every living thing. In this episode of Crash Course Biology, we’ll uncover the levels of biological organization, discover soil’s superpowers, and find out why the biosphere is kind of like a really, really long train. Air Date : 11th-Jul-2023  Read More

Season 2 Episode 5 - Why Did All These Elephants Die? (Intro to Ecology)

Ecology is the study of the interactions of living things with each other and their environment. It’s a field that not only lets us explore the interconnections between living things, but also how our environment affects us, and how we influence it in turn. In this episode of Crash Course Biology, we’ll get an overview of the field of ecology, see how matter and energy are conserved and transferred through ecosystems, and follow an ecological mystery surrounding the deaths of hundreds of elephants in Botswana, Africa. Air Date : 18th-Jul-2023  Read More

Season 2 Episode 6 - How Species Make and Break Friendships (Community Ecology)

Community ecology is the study of interactions between different species of living things, and lets ecologists examine the effects of predator-prey relationships, parasites, and mutually beneficial interactions. In this episode of Crash Course Biology, we’ll examine the myriad interspecies interactions with examples, see how keystone species impact their environment and explore how communities rebuild when they are disrupted, through the lens of the 1980 eruption of Mount St. Helens. Air Date : 1st-Aug-2023  Read More

Season 2 Episode 7 - How Did We Save The Bald Eagle? (Population Ecology)

When the Bald Eagle population started to decline in the mid-20th century, scientists began to ask why. Population ecology, the study of organisms of the same species, played a big role in answering that question. In this episode of Crash Course Biology, we’ll take a look at the methods population ecologists use to study a population and the types of data they collect. We’ll also find out how scientists helped bring the Bald Eagle back from the brink. Air Date : 8th-Aug-2023  Read More

Season 2 Episode 8 - What Is Climate Change?

Life on Earth has weathered boiling-hot oceans and volcanic-ash-darkened skies—but that’s nothing like the climate change we’re experiencing now. In this episode of Crash Course Biology, we’ll talk about the greenhouse effect, learn why our climate is like a tangled pair of headphones, and discover that we’ve understood the science behind climate change for much longer than you might think. Air Date : 15th-Aug-2023  Read More

Season 2 Episode 9 - The Effects of Climate Change

Climate change shakes up all of Earth’s systems, including the living ones. In this episode of Crash Course Biology, we’ll see how climate change’s effects rattle the entire chain of life. Changes felt in one population ripple out to affect entire communities and ecosystems—whether they’re composed of pine trees, puffins, or people. Air Date : 22nd-Aug-2023  Read More

Season 2 Episode 10 - How Do We Keep Life's Jenga Tower From Toppling? (Conservation Biology)

Some scientists believe we are in the middle of Earth’s sixth mass extinction: a big, precarious game of Jenga that involves every ecosystem on the planet. In this episode of Crash Course Biology, we’ll see how conservation biology aims to restore habitat and preserve biodiversity. Along the way, we’ll see how environmental damage impacts human communities, and learn about wolves’ return to Yellowstone National Park. Air Date : 29th-Aug-2023  Read More

Season 2 Episode 11 - What a weirdly long giraffe nerve can teach us about evolution

From a single-celled common ancestor, evolution has brought us all of Life’s Greatest Hits — including butterflies, beetles, bacteria, and human beings. In this episode of Crash Course Biology, we’ll learn how evolution explains life’s unity and diversity. Along the way, we’ll explore the fishy origins of a giraffe’s neck, and find out what a cat’s paw and your own arm have in common. Air Date : 5th-Sep-2023  Read More

Season 2 Episode 12 - Microevolution: What's An Allele Got To Do With It?

Whether we’re talking about tigers, trees, or tarantulas, evolution happens at the level of the population. In this episode of Crash Course Biology, we’ll find out how natural selection, gene flow, genetic drift, and other processes drive changes in populations. We’ll learn about the Hardy-Weinberg equation, how your alleles make you uniquely you, and how some tigers changed their stripes. Air Date : 12th-Sep-2023  Read More

Season 2 Episode 13 - Natural Selection: Life's Way of Stayin' Alive

There are lots of ways that evolution happens, and natural selection is just one of them. In this episode of Crash Course Biology, we’ll find out how this process works and shapes traits in all living things —from ginkgo trees to howler monkeys. We’ll also learn how extra-grippy toes help some lizards survive hurricanes. Air Date : 19th-Sep-2023  Read More

Season 2 Episode 14 - Why do we have different skin colors? (Population Genetics)

In this episode of Crash Course Biology, we’ll learn about the ways population genetics reveals how groups of living things evolve—by comparing genetic similarities and differences. We’ll discover the most genetically diverse species of all (hint: it’s not us), find out why “race” isn’t the biologically valid category we’ve made it out to be, and learn there’s much more in our DNA that we share than that sets us apart. Air Date : 4th-Oct-2023  Read More

Season 2 Episode 15 - Where Do Species Come From? (Speciation)

How can you tell two species apart? It’s not always simple. In this episode of Crash Course Biology, we’ll learn about speciation—a process that can happen over millions of years, or within a single generation. Along the way, we’ll discover how a single species can split into two and how a reptile from New Zealand continues to stump scientists. Air Date : 10th-Oct-2023  Read More

Season 2 Episode 16 - How did life begin? (Evolutionary History)

Humans may have been around for a long time, but life has existed for way longer. In this episode of Crash Course Biology, we’ll journey through deep time to uncover the history of life on Earth. We’ll explore the big, game-changing leaps where life diversified, changed, and just plain persisted. Air Date : 17th-Oct-2023  Read More

Season 2 Episode 17 - How We're All Related (Phylogeny)

Crocodiles, and birds, and dinosaurs—oh my! While classifying organisms is nothing new, phylogeny— or, grouping organisms by their evolutionary relationships—is helping us see life in a whole new light. In this episode of Crash Course Biology, we’ll learn why this kingdom-phylum stuff is going out of style and why phylogenetic trees are in. Air Date : 24th-Oct-2023  Read More

Season 2 Episode 18 - Humans Develop Butt First (and other insights from the Tree of Life)

Everywhere you look on Earth, you’ll find wonderful and diverse living things, from tiny tardigrades to soaring sequoias. And incredibly, everything alive today, and everything that’s ever lived, is related. In this episode of Crash Course Biology, we reveal how the evolutionary relationships between living things define their place on a single, great Tree of Life, and we learn what that tree can tell us about our own place among the planet’s biodiversity. Air Date : 31st-Oct-2023  Read More

Season 2 Episode 19 - Humans Didn't Evolve From Chimps (Human Evolution)

What’s a human? And how did we become humans, anyway? In this episode of Crash Course Biology, we’ll meet some of our closest relatives and trace how we evolved into the brainy, inventive, complex species we are today. Air Date : 7th-Nov-2023  Read More

Season 2 Episode 20 - What is Life Made of? (Carbon & Biological Molecules)

Despite the diverse appearance and characteristics of organisms on Earth, the chemicals that make up living things are remarkably similar, often identical. In this episode of Crash Course Biology, we’ll look at the building blocks of the four major classes of biomolecules, how those join up to form macromolecules, and how a team of six atoms forms the vast majority of living matter. Air Date : 14th-Nov-2023  Read More

Season 2 Episode 21 - A Love Letter to H2O: Water & pH

This is a love letter to water, life’s solvent, and one of the most wonderful molecules around. In this episode of Crash Course Biology, we’ll learn about how water’s polarity and hydrogen bonding help it sustain life on a larger scale. We’ll see how some water-based solutions can be acidic or basic, and examine how our bodies maintain the narrow pH range necessary for life. Air Date : 28th-Nov-2023  Read More

Season 2 Episode 22 - How We See What We Can't See (Microscopes)

There’s an immense world of tiny stuff within us and around us—but how do we know about it? In this episode of Crash Course Biology, we’ll discover how we see what we can’t see, thanks to the help of centuries-old tools and more recent technology. Along the way, we’ll learn about the major types of microscopes and how to use a typical light microscope. Air Date : 5th-Dec-2023  Read More

Season 2 Episode 23 - A Tour of the Cell

The cell is the basic unit of life, and our understanding of it has advanced as science, and the tools available to scientists, has advanced. In this episode of Crash Course Biology, we’ll take a look at the difference between prokaryotic and eukaryotic cells, take a guided tour of the eukaryotic cell, and learn why most cells are small. We’ll explore the eukaryotic cell’s surprising beginnings through an endosymbiosis that occurred about 1.5 billion years ago. Air Date : 12th-Dec-2023  Read More

Season 2 Episode 24 - How Does Stuff Get Into Your Cells? (Cell Membranes)

The cell membrane is a protein-studded phospholipid bilayer that not only protects our cells, but also regulates what goes in and out. In this episode of Crash Course Biology, we’ll look at the structure of the bilayer, learn about its discovery, and explore the many ways substances can be transported into and out of cells. Air Date : 19th-Dec-2023  Read More

Season 2 Episode 25 - How Do Cells Communicate? (Cell Communication)

Even though it might seem like our bodies are on autopilot, there is a whole lot happening inside us to keep things moving. In this episode of Crash Course Biology, we’ll learn that our cells are in constant communication, reminding each other—and themselves—to perform important functions like breathing, walking, or even sleeping. Air Date : 9th-Jan-2024  Read More

Season 2 Episode 26 - How Do We Get Energy? (Chemical Reactions)

Air Date : 16th-Jan-2024  Read More

Season 2 Episode 27 - How do cells get their energy? (Electron Transport Chain)

Air Date : 23rd-Jan-2024  Read More

Season 2 Episode 28 - Photosynthesis: The Original Solar Power

Air Date : 30th-Jan-2024  Read More

Season 2 Episode 29 - Mitosis and the Cell Cycle

Air Date : 6th-Feb-2024  Read More

Season 2 Episode 30 - Why Are All Humans Unique? Meiosis

Air Date : 14th-Feb-2024  Read More

Season 2 Episode 31 - Why Your Cat Looks Like That: Genetics

Air Date : 20th-Feb-2024  Read More