Why Do Things Keep Evolving Into Crabs?

October 28, 2020

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Eons - S4 - E33

For some reason, animals keep evolving into things that look like crabs, independently, over and over again. What is it about the crab’s form that makes it so evolutionarily successful that non-crabs are apparently jealous of it?

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Eons: Season 4 - 39 Episode s

4x1 - That Time the Mediterranean Sea Disappeared
January 9, 2020
How could a body of water as big as the Mediterranean just...disappear? It would take decades and more than 1,000 research studies to even start to figure out the cause -- or causes -- of one of the greatest vanishing acts in Earth’s history.
4x2 - The Neanderthals That Taught Us About Humanity
January 16, 2020
Throughout the first half of the 20th century, Neandertals were thought to have been…primitive. Unintelligent, hunched-over cavemen, for lack of a better word. But the discoveries made in that Iraqi cave provided some of the earliest clues that Neanderthals actually behaved -- and likely thought and felt -- a lot like we do.
4x3 - The Giant Dinosaur That Was Missing a Body
January 28, 2020
From end to end, its forelimbs alone measured an incredible 2.4 meters long and were tipped with big, comma-shaped claws. But other than its bizarre arms, very little material from this dinosaur had been found: no skull, no feet, almost nothing that could give experts a fuller picture of what this dinosaur actually was.
4x4 - How South America Made the Marsupials
February 4, 2020
Throughout the Cenozoic Era -- the era we’re in now -- marsupials and their metatherian relatives flourished all over South America, filling all kinds of ecological niches and radiating into forms that still thrive on other continents.
4x5 - A Short Tale About Diplodocus' Long Neck
February 11, 2020
Long necks gave sauropods a huge advantage when it came to food, but not in the way you think. And this benefit would allow them to become the biggest terrestrial animals of all time!
4x6 - When the Rainforests Collapsed
February 19, 2020
The Carboniferous Rainforest Collapse set the stage for a takeover that would be a crucial turning point in the history of terrestrial animal life. If it weren’t for that time when the rainforests collapsed - in an extinction event that you probably haven’t heard of - our ancestors might never have made it out of the swamps.
4x7 - How a Hot Planet Created the World's Biggest Snake
February 27, 2020
About 59 million years ago, the largest animal lurking in the ancient forests of Colombia by far was Titanoboa - the largest snake ever known. It’s only been in the past few years that we’ve put together the many pieces of this puzzling creature, but it turns out that the greatest snake that the world ever saw was made possible by a warming planet.
4x8 - When the Sahara Was Green
March 10, 2020
The climate of the Sahara was completely different thousands of years ago. And we’re not talking about just a few years of extra rain. We’re talking about a climate that was so wet for so long that animals and humans alike made themselves at home in the middle of the Sahara.
4x9 - When Penguins Went From The Sky To The Sea
March 18, 2020
Today, we think of penguins as small-ish, waddling, tuxedo-birds. But they evolved from a flying ancestor, were actual giants for millions of years, and some of them were even dressed a little more casually.
4x10 - How the Egg Came First
March 25, 2020
The story of the egg spans millions of years, from the first vertebrates that dared to venture onto land to today’s mammals, including the platypus, and of course birds. Like chickens? We’re here to tell you: The egg came first.
4x11 - How Dogs (Eventually) Became Our Best Friends
March 31, 2020
We’re still figuring out the details, but most scientists agree that it took thousands of years of interactions to develop our deep bond with dogs. When did they first become domesticated? Where did this happen? And what did the process look like, in terms of genetics and anatomy?
4x12 - When a Billion Years Disappeared
April 15, 2020
In some places, the rocks below the Great Unconformity are about 1.2 billion years older than those above it. This missing chapter in Earth’s history might be linked to a fracturing supercontinent, out-of-control glaciers, and maybe the diversification of life itself.
4x13 - The Risky Paleo Diets of Our Ancestors
April 22, 2020
We can track our history of eating just about anything back through the fossil record and see the impact it’s had on our evolution. Throughout time, part of the secret to our success as a species has been our early - and sometimes fatal - experimentation with food.
4x14 - How the Andes Mountains Might Have Killed a Bunch of Whales
April 29, 2020
At a site known as Cerro Ballena or Whale Hill, there are more than 40 skeletons of marine mammals -- a graveyard of ocean life dating back 6.5 million to 9 million years ago, in the Late Miocene Epoch. But the identity of the killer that they finally settled on might surprise you.
4x15 - How Plants Caused the First Mass Extinction
May 12, 2020
In the middle of the Cambrian, life on land was about to get a little more crowded. And those newcomers would end up changing the world. The arrival of plants on land would make the world colder, drain much of the oxygen out of the oceans and eventually, it would help cause a massive extinction event.
4x16 - The Two Viruses That We’ve Had For Millions of Years
May 20, 2020
There’s one kind of herpesvirus that’s specific to one species of primate, and each virus split off from the herpesvirus family tree when the primate split off from its own tree. But of course, humans are a special kind of primate.
4x17 - How We Identified One of Earth’s Earliest Animals
May 28, 2020
Scientists had no idea what type of organisms the life forms of the Ediacaran were—lichen, colonies of bacteria, fungi or something else. It turns out, the key to solving the puzzle of Precambrian life was a tiny bit of fossilized fat.
4x18 - When Dinosaur Look-Alikes Ruled the Earth
June 9, 2020
There were a huge number of croc-like animals that flourished during the Triassic Period. Dinosaurs had just arrived on the scene but it was these animals that truly ruled the Earth, becoming both abundant and diverse.
4x19 - The World Before Plate Tectonics
June 16, 2020
There was a time in Earth’s history that was so stable, geologists once called it the Boring Billion. But the fact is, this period was anything but boring. In fact, it set the stage for our modern version of plate tectonics - and probably for the rise of life as we know it.
4x20 - When Dinosaurs Chilled in the Arctic
June 24, 2020
All told, the Arctic in the Cretaceous Period was a rough place to live, especially in winter. And yet, the fossils of many kinds of dinosaurs have been discovered there. So how were they able to survive in this harsh environment?
4x21 - How the Walrus Got Its Tusks
July 7, 2020
The rise and fall of ancient walruses, and how modern ones got their tusks, is a story that spans almost 20 million years. And while there are parts of the story that we’re still trying to figure out, it looks like tusks didn’t have anything to do with how or what these animals ate.
4x22 - The Story of the Dino Stampede
July 16, 2020
To try to solve the puzzle of Lark Quarry, experts have turned to a special subfield of paleontology -- paleoichnology, or the study of trace fossils -- to reconstruct exactly what happened on that spot, on that day, nearly 100,000 millennia ago.
4x23 - The Biggest Frog that Ever Lived
July 23, 2020
Untangling the origins of Beelzebufo -- the giant frog that lived alongside the dinosaurs -- turns out to be one of the most bedeviling problems in the history of amphibians.
4x24 - The Dinosaur Who Was Buried at Sea
August 5, 2020
Paleontologists have been studying these dinosaurs since the 1830s, but nobody had ever found a specimen like Borealopelta before. The key to all of this exceptional preservation was where ended up after it died and how it got there.
4x25 - How We Figured Out Fermentation
August 13, 2020
Thanks to a recent adaptation, instead of getting sick from the boozy, fermented fruits, one of our primate ancestors could digest them safely, and get more calories at the same time. This new superpower would open up a whole new nutritional landscape for us: fermented foods.
4x26 - The Oddest Couple in the Fossil Record
August 20, 2020
To figure out how Thrinaxodon and Broomistega became entombed together, scientists looked at the burrow itself, along with their fossilized bones. And it looks like their luck ran out, when a behavior that usually would’ve helped them survive just didn’t work.
4x27 - How Ancient Art Captured Australian Megafauna
September 2, 2020
Beneath layers of rock art are drawings of animals SO strange that, for a long time, some anthropologists thought they could only have been imagined. But what if these animals really had existed, after all?
4x28 - The Sea Monster from the Andes
September 10, 2020
In 1977, a farmer was plowing his field on a plateau high in the Andes mountains when he stumbled upon a giant fossilized skeleton. How did this giant marine reptile end up high in the Andes Mountains?
4x29 - When Rodents Had Horns
September 15, 2020
These odd rodents belong to a genus known as Ceratogaulus, but they’re more commonly called horned gophers, because, you guessed it, they had horns. And it turns out the horns probably had a purpose - one that rodents would likely benefit from today.
4x30 - The First and Last North American Primates
September 30, 2020
Early primates not only lived in North America -- our primate family tree actually originated here! So what happened to those early relatives of ours?
4x31 - How Plants Became Carnivores
October 7, 2020
How and why does botanical carnivory keep evolving? It turns out that when any of the basic things that most plants need aren’t there, some plants can adapt in unexpected ways to make sure they thrive.
4x32 - How Ankylosaurs Got Their Clubs
October 13, 2020
While clubs are practically synonymous with ankylosaurs, we’ve only started to get to the bottom of how they worked and how this unusual anatomy developed in the first place.
4x33 - Why Do Things Keep Evolving Into Crabs?
October 28, 2020
For some reason, animals keep evolving into things that look like crabs, independently, over and over again. What is it about the crab’s form that makes it so evolutionarily successful that non-crabs are apparently jealous of it?
4x34 - How Plankton Created A Bizarre Giant of the Seas
November 10, 2020
At more than 2 meters long, Aegirocassis was not only the biggest radiodont ever, but it also may have been the biggest animal in the Early Ordovician. This bizarre marine giant may have only been possible, thanks to a major revolution among some of the tiniest organisms in the world.
4x35 - The Rise and Fall of the Tallest Mammal to Walk the Earth
November 19, 2020
It arose from rhino ancestors that were a lot smaller, but Paraceratherium would take a different evolutionary path. Believe it or not, it actually became so big that it probably got close to what scientists think might be the actual upper limit for a land mammal.
4x36 - How Humans Lost Their Fur
December 2, 2020
We’re the only primate without a coat of thick fur. It turns out that this small change in our appearance has had huge consequences for our ability to regulate our body temperature, and ultimately, it helped shape the evolution of our entire lineage.
4x37 - When Lizards Took Over the World
December 9, 2020
Lizards are incredibly widespread and diverse but it took them a long time to get to where they are now. Because they used to face some pretty stiff competition from a group of lizard look-alikes.
4x38 - When the Earth Suddenly Stopped Warming
December 17, 2020
For decades, scientists have been studying the cause of the Younger Dryas, and trying to figure out if something like it could happen again. And it turns out that what caused this event is the subject of a heated debate.
4x39 - The Triassic Reptile With "Two Faces"
December 22, 2020
Figuring out what this creature’s face actually looked like would take paleontologists years. But understanding this weird animal can help us shine a light on at least one way for ecosystems to bounce back from even the worst mass extinction.

4x1 - That Time the Mediterranean Sea Disappeared

4x2 - The Neanderthals That Taught Us About Humanity

4x3 - The Giant Dinosaur That Was Missing a Body

4x4 - How South America Made the Marsupials

4x5 - A Short Tale About Diplodocus' Long Neck

4x6 - When the Rainforests Collapsed

4x7 - How a Hot Planet Created the World's Biggest Snake

4x8 - When the Sahara Was Green

4x9 - When Penguins Went From The Sky To The Sea

4x10 - How the Egg Came First

4x11 - How Dogs (Eventually) Became Our Best Friends

4x12 - When a Billion Years Disappeared

4x13 - The Risky Paleo Diets of Our Ancestors

4x14 - How the Andes Mountains Might Have Killed a Bunch of Whales

4x15 - How Plants Caused the First Mass Extinction

4x16 - The Two Viruses That We’ve Had For Millions of Years

4x17 - How We Identified One of Earth’s Earliest Animals

4x18 - When Dinosaur Look-Alikes Ruled the Earth

4x19 - The World Before Plate Tectonics

4x20 - When Dinosaurs Chilled in the Arctic

4x21 - How the Walrus Got Its Tusks

4x22 - The Story of the Dino Stampede

4x23 - The Biggest Frog that Ever Lived

4x24 - The Dinosaur Who Was Buried at Sea

4x25 - How We Figured Out Fermentation

4x26 - The Oddest Couple in the Fossil Record

4x27 - How Ancient Art Captured Australian Megafauna

4x28 - The Sea Monster from the Andes

4x29 - When Rodents Had Horns

4x30 - The First and Last North American Primates

4x31 - How Plants Became Carnivores

4x32 - How Ankylosaurs Got Their Clubs

4x33 - Why Do Things Keep Evolving Into Crabs?

4x34 - How Plankton Created A Bizarre Giant of the Seas

4x35 - The Rise and Fall of the Tallest Mammal to Walk the Earth

4x36 - How Humans Lost Their Fur

4x37 - When Lizards Took Over the World

4x38 - When the Earth Suddenly Stopped Warming

4x39 - The Triassic Reptile With "Two Faces"

S0: Specials

S1: Season 2017

S2: Season 2018

S3: Season 2019

S4: Season 2020

S5: Season 2021

S6: Season 2022