Human Footprint

Billions of American chestnut trees once shaped life in Appalachia, but a foreign fungus erased them in a matter of decades. Today, only sickly sprouts remain — ghosts of a vanished ecosystem. Sara Fern Fitzsimmons and The American Chestnut Foundation are racing to breed resistance and restore the tree's ecological role. It’s slow, painstaking work — but it may hold the key to revival.

From fossils entombed in tar to cells frozen in hope, Shane Campbell-Staton traces the arc of extinction from prehistory to the present. On an epic global journey, he meets species at the brink of oblivion… and the people who won’t give up on them.

Paleontologist Emily Lindsey uncovers the past beneath the streets of Los Angeles at the La Brea Tar Pits — home to the richest Ice Age fossil deposit in the world. Once mined for oil, this sticky site has revealed giant ground sloths, saber-toothed cats, and over five million fossils. It's a fossil jackpot that tells a 40,000-year-old story of life, extinction, and climate change.

In Kenya, elephants and humans often live side-by-side — but not always peacefully. Shane meets David Mwiti, a farmer impacted by crop-raiding elephants, and John Pameri, a security expert at Lewa Wildlife Conservancy, who helps prevent conflict. With fences, GPS collars, and deep community investment, Lewa is rewriting the rules of coexistence between people and megafauna.

Orca researcher Dr. Deborah Giles and her scent-detecting dog, Eba, are racing to save the southern resident killer whales — an endangered group with just 73 members left. By tracking orca poop, they gather vital data on stress, pregnancy, diet, and health. With Chinook salmon populations collapsing, these orcas are starving, and Giles is fighting to change their fate — one scat sample at a time.

The northern white rhino teeters on the brink of extinction. At Ol Pejeta Conservancy and the San Diego Zoo’s Frozen Zoo, scientists, vets, and caregivers like Zach Mutai, Marlys Houck, and Dr. Florence Kang’ethe are racing against time to bring the species back. Through groundbreaking science and deep compassion, they’re writing a hopeful final chapter — before the book closes for good.

The Colorado River Delta was once a lush wetland. After decades of damming and diversion, it dried up — until a rare pulse flow brought water, beavers, and hope back. Aída Navarro leads a movement to reconnect communities and nature, proving that with care and coordination, deserts can bloom again. But as water politics intensify, the future remains uncertain.

Las Vegas thrives in one of the driest places on Earth thanks to engineering feats and strict water laws. Shane meets Colby Pellegrino and Cameron Donnarumma of the Southern Nevada Water Authority and visits the world’s oldest hydraulic dam in Italy with Giulio Boccaletti to explore what it takes — and what it costs — to bend water to human will.

Shane Campbell-Staton travels from ancient aqueducts to modern mega-dams, following our age-old quest to tame water. On a journey down the Colorado River, he discovers how humanity’s thirst for control has reshaped rivers — and civilization itself.

Biologist Lindsay Hansen and her USGS team work day and night to study the federally threatened humpback chub in the Grand Canyon. Using PIT tags, they track fish growth and migration to understand how this resilient species adapts to cold dam flows and warming tributaries like the Little Colorado. Their efforts offer a glimpse of hope in an altered ecosystem.

The Salton Sea once rivaled Yosemite in tourist visits. Today, it’s a toxic environmental disaster. Luis Olmedo of Comite Civico del Valle connects the dots between industrial runoff, migrant farmworkers, and the health crisis brewing at this shrinking desert lake. What’s being done to save it — if anything?

The Glen Canyon Dam once symbolized American engineering might. But the Colorado River it was built to tame is shrinking. Shane meets dam managers, river advocates, and tribal leaders to explore the legacy — and limitations — of the West’s water megaprojects. Can a 20th-century marvel survive the realities of a 21st-century climate?