The short-faced bears turned out to be remarkably adaptable, undergoing radical changes to meet the demands of two changing continents. And yet, for reasons we don’t quite understand, their adaptability wasn’t enough to keep them from going extinct.

The ability to make and use fire has fundamentally changed the arc of our evolution. The bodies we have today were, in many ways, shaped by that time when we first tamed fire.

Sea scorpions thrived for 200 million years, coming in a wide variety of shapes and sizes. Over time, they developed a number of adaptations–from crushing claws to flattened tails for swimming. And some of them adapted by getting so big that they still hold the record as the largest arthropods of all time.

The tools made by our human ancestors may not seem like much when you compare them to the screen you’re looking at right now but their creation represents a pivotal moment in the origin of technology and in the evolution of our lineage.

Back in the late Miocene epoch, there was an island–or maybe a group of islands– in the Mediterranean Sea that was populated with fantastic giant beasts. It’s a lesson in the very strange, but very real, powers of natural selection.

Strange geologic landmarks in the Pacific Northwest are the lingering remains of a mystery that took nearly half a century to solve. These features turned out to be a result one of the most powerful and bizarre episodes in geologic history: this region experienced dozens of major, devastating floods over the course of more than 7,000 years.

In order to understand where hearts came from, we have to go back to the earliest common ancestor of everything that has a heart. It took hundreds of millions of years, and countless different iterations of the same basic structure to lead to the heart that you have today.

As more and more fossil ancestors have been found, our genus has become more and more inclusive, incorporating more members that look less like us, Homo sapiens. By getting to know these other hominins–the ones who came before us–we can start to answer some big questions about what it essentially means to be human.

Blood is one of the most revolutionary features in our evolutionary history. Over hundreds of millions of years, the way in which blood does its job has changed over and over again. As a result, we animals have our familiar red blood. But also blue blood. And purple, and green, and even white.

Not too long ago, our early human ancestors were under constant threat of attack from predators. And it turns out that this difficult chapter in our history may be responsible for the adaptations that allowed us to become so successful.

For more than 10 million years, Megalodon was at the top of its game as the oceans’ apex predator…until 2.6 million years ago, when it went extinct. So, what happened to the largest shark in history?