The Air You Breathe Is Bacteria Poop | Peter Girguis

How Many Leaves Are on a Tree? | Kirk Johnson

Need to know how many leaves are on that tree? Paleobotanist Dr. Kirk Johnson shares the surprisingly nerdy method—because you never know when leaf math will come in handy. For more, check out the extended interview [https://www.wgbh.org/podcasts/particles-of-thought/extended-interview-fossil-hunting-sinkholes-and-paleobotany-with-kirk-johnson] with Kirk Johnson. Learn more about NOVA [https://www.pbs.org/wgbh/nova/] and subscribe to our YouTube [https://www.youtube.com/channel/UCjHz5SVHeMT0AViCYZvsGDA]channel.

Decoding the Great Pyramid

What engineering secrets lie within the Great Pyramid, and who really built it? Innovations like rope‑sewn boats, laser‑precise alignments, and hidden internal chambers reveal a building team with knowledge far ahead of its time. Uncover clues buried around Giza that point to a surprising truth about the workforce responsible for one of history’s greatest construction projects. To watch the full film, visit https://www.pbs.org/wgbh/nova/video/decoding-the-great-pyramid/ [https://www.pbs.org/wgbh/nova/video/decoding-the-great-pyramid/] Learn more about NOVA [https://www.pbs.org/wgbh/nova/] and subscribe to our YouTube [https://www.youtube.com/channel/UCjHz5SVHeMT0AViCYZvsGDA]channel.

The Air You Breathe Is Bacteria Poop | Peter Girguis

Long before trees and grass, microbes were shaping our atmosphere. Evolutionary biologist Peter Girguis explains how ancient bacteria learned to split water for energy, and why their waste product changed Earth forever. For more, check out the extended interview [https://www.wgbh.org/podcasts/particles-of-thought/extended-interview-extremophiles-the-deep-sea-and-alien-life-with-peter-girguis] with Peter Girguis. Learn more about NOVA [https://www.pbs.org/wgbh/nova/] and subscribe to our YouTube [https://www.youtube.com/channel/UCjHz5SVHeMT0AViCYZvsGDA]channel.

The Fish That Could Walk | Sean B. Carrol

How did animals first make the giant step from water to land? Evolutionary biologist Sean B. Carroll explains how the discovery of Tiktaalik—a fossil with both fish and limb-like features—revealed a key moment in evolution. For more, check out the extended interview [https://www.wgbh.org/podcasts/particles-of-thought/evolution-of-new-species-venom-wings-and-more-extended-interview-with-sean-b-carroll]with Sean B. Carroll. Learn more about NOVA [https://www.pbs.org/wgbh/nova/] and subscribe to our YouTube [https://www.youtube.com/channel/UCjHz5SVHeMT0AViCYZvsGDA]channel.

When Whales Could Walk

What if whales had legs? Once upon a time, they did. Sort of. An astonishing fossil trail shows that modern whales actually evolved from hooved land mammals. Whales still carry the fingerprints of this past, from their stomach anatomy to their swimming gait. Dive in to discover the wild story of how whales traded legs for fins, as we uncover clues about their ancestors, as well as their unlikely present-day relatives. To watch the full film, visit https://www.pbs.org/wgbh/nova/video/when-whales-could-walk/ [https://www.pbs.org/wgbh/nova/video/when-whales-could-walk/] Learn more about NOVA [https://www.pbs.org/wgbh/nova/] and subscribe to our YouTube [https://www.youtube.com/channel/UCjHz5SVHeMT0AViCYZvsGDA]channel.