On December 28, 2023, the Endangered Species Act (ESA) turned 50 years old. It was enacted in 1973 with almost unanimous support in Congress, with a goal to save plants and animals from extinction. It’s considered one of the most important environmental policies in US history, and it transformed conservation. It may have even helped save one of your favorite critters, like humpback whales, bald eagles, manatees, and grizzly bears.To mark the ESA’s 50th birthday, we’re looking at how it works, how successful it’s been, and what its future may look like. Ira starts off by talking with Dr. Judy Che-Castaldo, biologist for the US Fish and Wildlife Service’s Branch of Species Status Assessment Science Support.Then, we head to the extinction capital of the world: Hawai‘i. Kāhuli, also known as Hawaiian land snails, live all over the Hawaiian islands. At one point, around 750 species existed, but more than half have gone extinct. Ira talks with two conservationists dedicated to saving the snails: Dr. David Sischo, coordinator of the Hawai‘i Snail Extinction Prevention Program, and Keahi Bustamente, Maui Nui field coordinator for the program.Transcripts for each segment will be available after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.