In Egypt’s Sahara Desert, massive skeletons with strange skulls and gigantic teeth jut out from the sandy ground. This fossil graveyard, millions of years old, is known as the “Valley of the Whales.” Now, paleontologists have unearthed a whole new species of ancient whale dating to 43 million years ago, and this predator wasn’t just able to swim – it also had four legs and could walk. Follow scientists as they search for new clues to the winding evolutionary path of mammals that moved from the land into the sea to become the largest animals on Earth.

How were the giant stone heads of Rapa Nui–also known as Easter Island–carved and raised, and why? Since Europeans arrived on this remote Pacific island over 300 years ago, controversy has swirled around the iconic ancient statues and the history of the people who created them. Now, a new generation of researchers is overturning old theories, revealing the rich history, innovation, and resilience of the Rapanui people, and uncovering intriguing new evidence about where they–and their practice of monumental stone building–came from.

Explore the revolutionary engineering behind Paris’s iconic landmark. Completed in just over two years for the 1889 World’s Fair, the iron tower smashed the record for the tallest structure on Earth, ushering in a new age of global construction that reached for the skies. How did the engineers do it? Follow the innovations, successes, and failures that made one of the most famous buildings on the planet possible.

For decades, scientists have tried to unlock the secrets of ancient DNA. But life’s genetic blueprint is incredibly fragile, and researchers have struggled to find DNA in fossils that could survive millions of years. Then, one maverick scientist had the controversial idea to look for DNA not in fossils or frozen ancient tissue – but in dirt. Join the hunt as scientists decipher the oldest DNA ever found, and reveal for the first time the genes of long-extinct creatures that once thrived in a warm, lush Arctic.

Can we harness the power of artificial intelligence to solve the world’s most challenging problems without creating an uncontrollable force that ultimately destroys us? ChatGPT and other new A.I. tools can now answer complex questions, write essays, and generate realistic-looking images in a matter of seconds. They can even pass a lawyer’s bar exam. Should we celebrate? Or worry? Or both? Correspondent Miles O’Brien investigates how researchers are trying to transform the world using A.I., hunting for big solutions in fields from medicine to climate change.

Explore the spectacular cosmic phenomenon of a total solar eclipse. In April 2024, the Moon’s shadow is sweeping from Texas to Maine, as the U.S. witnesses its last total solar eclipse until 2044. This extraordinary astronomical event is plunging locations in the path of totality into darkness for more than four minutes – nearly twice as long as the last American eclipse in 2017. Learn how to watch an eclipse safely and follow scientists as they work to unlock secrets of our Sun – from why its atmosphere is hundreds of times hotter than its surface, to what causes solar storms and how we might one day predict them.

Whether you’re on social media or surfing the web, you’re probably sharing more personal data than you realize. That can pose a risk to your privacy – even your safety. But at the same time, big datasets could lead to huge advances in fields like medicine. Host Alok Patel leads a quest to understand what happens to all the data we’re shedding and explores the latest efforts to maximize benefits – without compromising personal privacy.