Mammals with pouches, like this red kangaroo, didn't originate in Australia, but they have prospered there like nowhere else on the planet. Why?

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How did Australia come to be marsupial heaven?

Evolution Down Under

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Athens: Birth of Democracy

Archaeologists investigate the dramatic origins of democracy in ancient Greece 2,500 years ago.
The United States has experimented with democracy for 250 years, but our system of government was once a radical idea, born in ancient Greece. Ravaged by civil war and tyranny 2,500 years ago, the city of Athens forged a revolutionary new system that gave power to the citizens. Witness the archaeological quest to unearth the ingenious tools and pivotal moments that shaped this unprecedented experiment in self-government. From mysterious fragments of ancient voting machines to mass graves and dramatic assassinations, discover the dark secrets and innovative solutions that defined the world&#x27;s first direct democracy. What enduring lessons can this surprising historical journey offer us today? (Premiering April 15, 2026 at 9 pm on PBS)

Archaeologists investigate the dramatic origins of democracy in ancient Greece 2,500 years ago.

When Earth Was Bombarded by Asteroids

What studying the surface of the Moon revealed about Earth’s apocalyptic youth.
Four and a half billion years ago, Earth was battered by relentless asteroid impacts powerful enough to vaporize oceans and melt its crust. Despite the chaos, life emerged anyway.
When Earth Was Bombarded by AsteroidsPublished: January 30, 2025NARRATOR: Craters are a reminder of our solar system&#x27;s formation around 4.56 billion years ago. It began as a disc of dust and gas in orbit around the young sun. The solid materials collided and clumped together to gradually form the rocky planets.SIMONE MARCHI: As a result of the formation of the earth, there were still lots of debris and asteroids and other smaller objects flying around the sun. Those objects kept colliding with the surface of the earth.NARRATOR: About four and a half billion years ago, a single object the size of Mars or even bigger may have crashed into the young earth. This high resolution simulation reveals how the collision flung enough molten and vaporized debris into space to create the moon.SIMONE MARCHI: I&#x27;m trying to understand the early evolution of the earth and the effects of all those impacts that were taking place during the idea on the earth. So we do this by building models.NARRATOR: One of the most important sources of data comes from NASA&#x27;s lunar reconnaissance mission. This robotic spacecraft has made a 3D map of the moon&#x27;s surface at extremely high resolution.SIMONE MARCHI: The first thing that we do is to look at the surface of the moon. It is much older than the surface of the earth. The surface of the moon is full of impact graters, all the impact graters, and so we can use that information by mapping how many there are and their sizes and their ages, and that will provide us the primary information that we need to build our models.NARRATOR: It took an international team decades to collect the data. But they finally created a computer model that took what happened on the moon during the Hadean and simulated the asteroids that would&#x27;ve hit the earth during the same stretch of time.SIMONE MARCHI: And the outcome of that, our first modeling was staggering. We are seeing the entire surface of the earth that is strongly affected by impact. Every single circle that you see here is an impact, is a collision.The prediction was that there were a tremendous number of impacts, even large one. Imagine an object the size of the moon that could have collided with the earth. That would have basically wiped out almost entirely perhaps the oceans, vaporized the oceans and melted a large portion of the crust of the earth.NARRATOR: This series of apocalyptic bombardments might look like it created a chaotic hellscape on earth. Even during asteroid impacts, there must have been enough habitable conditions somewhere on the planet for life to get a foothold.

What studying the surface of the Moon revealed about Earth’s apocalyptic youth.

Spacecraft passing in front of the moon with the Earth in the background

Return to the Moon

Follow the Artemis mission to bring humanity back to the Moon for the first time since Apollo.
A half-century after American astronauts walked on the Moon, NASA and its international partners are taking the dream of Apollo a giant step further. In the coming years, the Artemis missions – named after Apollo&#x27;s twin sister in Greek mythology – aim to bring astronauts back to the Moon and establish a lunar space station for scientific and commercial exploration. Follow the four members of the Artemis II crew as they embark on a perilous 10-day journey to orbit the Moon, venturing beyond Earth orbit for the first time since Apollo and farther into the Solar System than any humans have gone before. And get an inside look at the preparations needed to overcome the extreme engineering challenges of human-crewed spaceflight, all the way from launch to splashdown. &quot;Return to the Moon&quot; will be available shortly after the completion of the Artemis II mission&quot;

Follow the Artemis mission to bring humanity back to the Moon for the first time since Apollo.

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Stone Age Temple Mystery

Surprising evidence at the world’s oldest temple overturns our understanding of human history.

Interview: Discovering Dark Energy and the Hubble Tension with Nobel Prize Winner Adam Riess

What happens when your data rewrites the laws of physics? Adam Riess takes us inside the discovery of dark energy.

This Discovery Rewrote Human History

In a remote cave, in North West Africa, a chance discovery uncovered some mysterious human remains.
For the longest time, we thought we knew the origins of our species. We thought we began 200,000 years ago in East Africa. But new revelations from out here in Morocco, from a part of Africa that people weren’t really considering, are forcing us to rethink our very first steps on this planet.
This Discovery Rewrote Human HistoryPublished: December 11, 2025ELLA AL-SHAMAHI: Several decades after the initial discoveries came a breakthrough. Archaeologists uncovered another 16 fossils, all with the same blend of features. And taken together with the old finds, a fuller picture started to emerge.ABDELOUAHED BEN-NCER: (Translated from Arabic) This is another fossil we excavated. It’s part of the lower jaw.ELLA AL-SHAMAHI: (Translated from Arabic) From this skull?ABDELOUAHED BEN-NCER: (Translated from Arabic) No, no, from a child.And this one from another adult.ELLA AL-SHAMAHI: (Translated from Arabic) And how old?ABDELOUAHED BEN-NCER: (Translated from Arabic) Around eight years old.ELLA AL-SHAMAHI: (Translated from Arabic) So, between the old and new discoveries?ABDELOUAHED BEN-NCER: (Translated from Arabic) Yes, collectively a group of young and old were found at the site.ELLA AL-SHAMAHI: With each new find the evidence grew. These were not some other species, but Homo sapiens, with hints of an earlier ancestor. But it wasn’t until archaeologists were able to more accurately date the remains that the final piece of the puzzle fell into place.The archaeologists, using new and improved dating techniques, were able to give us dates for these fossils. And they tell us that these individuals lived about 300,000 years ago. And that is mind-boggling, because we thought our species was only about 200,000 years old. What these fossils tells us is that our species, Homo sapiens, is 100,000 years older than we thought.We are much older than we realized. This fossil went from being enigmatic and a, basically a mystery, to being one of the most important fossils in our whole field.Thousands of miles from East Africa, where many anthropologists thought we began, and far older than expected, these are the earliest Homo sapiens ever found. And they have forced us to re-think other finds across Africa, which are painting an entirely new picture of our origins, suggesting Jebel Irhoud was just one of many emerging Homo sapiens populations.

In a remote cave, in North West Africa, a chance discovery uncovered some mysterious human remains.

This Was One of the First Known Human Ritual Sites

Early humans may have brought offerings to this enormous stone snake.
In a secluded Botswana cave, a natural stone outcropping was carved to resemble a python. Archaeologists think this could be one of the world’s earliest ritual sites.
This Was One of the First Known Human Ritual SitesPublished: December 11, 2025SHEILA COULSON: The front has a natural slit for a mouth and a natural depression for an eye. And even if you want to go that far, a nostril up at the front. With the head rearing up, it does in modern eyes look like a snake.The overall form has been altered to make it look even more snake-like. There are over 300 indentations that have been ground into the surface over what is obviously an extended period of time. When the initial excavations were conducted, they absolutely revealed a number of questions. One of the things found was an extremely large number of tools that appeared to be manufactured and then just left there in pristine condition.ELLA AL-SHAMAHI: These look gorgeous. I mean, they&#x27;re absolutely stunning.SHEILA COULSON: Once they were manufactured, then you did one of three things with it. You either manufactured it perfectly and just left it. Or more interestingly, you burnt it. But not burnt to just like throwing it in a bonfire. It&#x27;s controlled burning. And the third and most bizarre thing that they did with them is they made it, manufactured it perfectly, and when they were finished, turned it over, smashed it in the middle.ELLA AL-SHAMAHI: This behavior suggests that people were likely coming here to make offerings, which tells us something about how their minds worked.SHEILA COULSON: Although it&#x27;s absolutely magnificent during the daytime, it comes to life at night. You make an offering and hope for something back.ELLA AL-SHAMAHI: Asking for probably some of the things that we would ask for, food, health, children, et cetera, et cetera. And you just think, &quot;Oh my gosh, that&#x27;s some of the earliest behavior that we know so well.&quot;

Early humans may have brought offerings to this enormous stone snake.

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