Eons Season 3, Episode 22: How Volcanoes Froze the Earth (Twice)

1

When Humans Were Prey

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.

10 min

2

How Blood Evolved (Many Times)

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.

10 min

3

The Humans That Lived Before Us

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.

10 min

4

The Island of Shrinking Mammoths

The mammoths fossils found on the Channel Islands off the coast of southern California are much smaller than their relatives found on the mainland. They were so small that they came to be seen as their own species. How did they get there? And why were they so small?

10 min

5

The Evolution of the Heart (A Love Story)

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.

10 min

6

How 7,000 Years of Epic Floods Changed the World

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.

10 min

7

The Island of Huge Hamsters and Giant Owls

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.

10 min

8

The Giant Bird That Got Lost in Time

The California condor is the biggest flying bird in North America, a title that it has held since the Late Pleistocene Epoch. It's just one example of an organism that we share the planet with today that seems lost in time, out of place in our world.

10 min

9

When We First Made Tools

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.

10 min

10

When Giant Scorpions Swarmed the Seas

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.

10 min

11

When We Tamed Fire

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.

10 min

12

The Mystery Behind the Biggest Bears of All Time

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.

10 min

13

The Croc That Ran on Hooves

In the Eocene Epoch, there was a reptile that had teeth equipped for biting through flesh, its hind legs were a lot longer than its front legs and instead of claws, its toes were each capped with hooves. How did this living nightmare come to evolve?

10 min

14

When We Took Over the World

From our deepest origins in Africa all the way to the Americas, by looking at the fossils and archaeological materials we have been able to trace the path our ancestors took during thee short window of time when we took over the world.

10 min

15

The Ghostly Origins of the Big Cats

All of today’s big cat species evolved less than 11 million years ago and yet their evolutionary history remains an almost total mystery. But scientists have recently discovered a major clue about the origins of the big cats, one that could provide a whole new starting place for solving this puzzle.

10 min

16

The History of Climate Cycles (and the Woolly Rhino) Explained

Throughout the Pleistocene Epoch, the range of the woolly rhino grew and shrank in sync with global climate. So what caused the climate -- and the range of the woolly rhino -- to cycle back and forth between such extremes?

10 min

17

The Hellacious Lives of the "Hell Pigs"

Despite the name, we don’t know where the so-called “hell pigs” belong in the mammalian family tree. They walked on hooves, like pigs do, but had longer legs, almost like deer. They had hunched backs, a bit like rhinos or bison. But as is often, if not always, the case, there is some evolutionary method to this anatomical madness.

10 min

18

How Evolution Works (And How We Figured It Out)

As a scientific concept, evolution was revolutionary when it was first introduced. With the help of all three of our hosts and the Smithsonian National Museum of Natural History’s new Deep Time Hall, we’ll try to explain how evolution actually works and how we came to understand it.

10 min

19

When the Synapsids Struck Back

Synapsids were the world’s first-ever terrestrial megafauna but the vast majority of these giants were doomed to extinction. However some lived on, keeping a low profile among the dinosaurs. And now our world is the way it is because of the time when the synapsids struck back.

10 min

20

When Ichthyosaurs Led a Revolution in the Seas

The marine reptiles Ichthyosaurs arose after The Great Dying, which wiped out at least 90 percent of life in the oceans, changing the seas forever and triggering a new evolutionary arms race between predator and prey.

10 min

21

When We Met Other Human Species

We all belong to the only group of hominins on the planet today. But we weren’t always alone. 100,000 years ago, Eurasia was home to other hominin species, some of which we know our ancestors met, and spent some quality time with.

10 min

22

How Volcanoes Froze the Earth (Twice)

Over 600 million years ago, sheets of ice coated our planet on both land and sea. How did this happen? And most importantly for us, why did the planet eventually thaw again? The evidence for Snowball Earth is written on every continent today.

10 min

23

How Earth's First, Unkillable Animals Saved the World

They have survived every catastrophe and every mass extinction event that nature has thrown at them. And by being the little, filter-feeding, water-cleaning creatures that they are, sponges may have saved the world.

10 min

24

When Giant Deer Roamed Eurasia

Megaloceros was one of the largest members of the deer family ever to walk the Earth. The archaeological record is full of evidence that our ancestors lived alongside and interacted with these giant mammals for millennia. But what happened when they did interact, when humans met this megafauna?

10 min

25

Was This Dinosaur a Cannibal?

Paleontologists have spent the better part of two decades debating whether Coelophysis ate its own kind. It turns out, the evidence that scientists have had to study in order to answer that question includes some of the strangest and grossest fossils that any expert would ever get to see.

10 min

26

The Missing Link That Wasn’t

The myth of the Missing Link--the idea that there must be a specimen that partly resembles an ape but also partly resembles a modern human--is persistent. But the reality is that there is no missing link in our lineage, because that’s not how evolution works.

10 min

27

The Raptor That Made Us Rethink Dinosaurs

In 1964, a paleontologist named John Ostrom unearthed some fascinating fossils from the mudstone of Montana. Its discovery set the stage for what’s known today as the Dinosaur Renaissance, a total re-thinking of what we thought we knew about dinosaurs.

10 min

28

When Bats Took Flight

Bats pretty much appear in the fossil record as recognizable, full-on, flying bats. And they show up on all of the continents, except Antarctica, around the same time. So where did bats come from? And which of the many weird features that bats have, showed up first?

10 min

29

How Pterosaurs Got Their Wings

When pterosaurs first took flight, you could say that it marked the beginning of the end for the winged reptiles. Because, strangely enough, the power of flight -- and the changes that it led to -- may have ultimately led to their downfall.

10 min

30

When Giant Lemurs Ruled Madagascar

Just a few thousand years ago, the island of Madagascar was inhabited by giant lemurs. How did such a diverse group of primates evolve in the first place, and how did they help shape the unique environments of Madagascar? And how did they get winnowed down, leaving only their smaller relatives behind?

10 min

31

When Antarctica Was Green

Before the start of the Eocene Epoch about 56 million years ago--Antarctica was still joined to both Australia and South America. And it turns out that a lot of what we recognize about the southern hemisphere can be traced back to that time when Antarctica was green.

10 min

32

The Case of the Dinosaur Egg Thief

Paleontologists found a small theropod dinosaur skull right on top of a nest of eggs that were believed to belong to a plant-eating dinosaur. Instead of being the nest robbers that they were originally thought to be, raptors like this one would reveal themselves to actually be caring parents.

10 min

33

When Hobbits Were Real

Its discoverers named it Homo floresiensis, but it’s often called “the hobbit” for its short stature and oddly proportioned feet. And it’s been at the center of a major controversy in the field ever since. Was it its own species? Or was it really just one of us? Or, could it even have descended from a whole lineage of hominins that we don’t even know about?

10 min

34

Were These Monsters Inspired by Fossils?

People have been discovering the traces and remains of prehistoric creatures for thousands of years. And they’ve also probably been telling stories about fantastic beasts since language became a thing. So, is it possible that the monsters that populate our myths and legends were influenced by the fossil record?

10 min

35

How We Domesticated Cats (Twice)

A 9,500 year old burial in Cyprus represents some of the oldest known evidence of human/cat companionships anywhere in the world. But when did this close relationship between humans and cats start? And how did humans help cats take over the world?

10 min

36

When Giant Hypercarnivores Prowled Africa

These hyaenodonts gave the world some of its largest terrestrial, carnivorous mammals ever known. And while these behemoths were the apex predators of their time, they were no match for a changing world.

10 min

37

Why Male Mammoths Lost the Game

Woolly mammoths, our favorite ice age proboscidean, disappeared from Europe and North America at the end of the last ice age, about 10,000 years ago. Today, we’ve teamed up with TierZoo to solve one of the mysteries about these charismatic megafauna: why do most remains of mammoths found in the fossil record turn out to be male?

10 min

38

The Forgotten Story of the Beardogs

Because of their strange combination of bear-like and dog-like traits, they’re sometimes confusingly called the beardogs. And even though you’ve never met one of these animals, the beardogs are key to understanding the history of an important branch of the mammal family tree.

10 min

39

The Fuzzy Origins of the Giant Panda

How does a bear -- which is a member of the order Carnivora -- evolve into an herbivore? Despite how it looks, nothing about the history of the giant panda is black and white.

10 min