Tracing the arrival of rats using bones, isotopes, and a few shipwrecks; and what scientists have learned in 50 years about our famous ancestor Lucy   First on the show: Did rats come over with Christopher Columbus? It turns out, European colonists weren’t alone on their ships when they came to the Americas—they also brought black and brown rats to uninfested shores. Eric Guiry, a researcher in the Trent Environmental Archaeology Lab at Trent University, joins host Sarah Crespi to discuss how tiny slices of bone from early colony sites and sunken shipwrecks can tell us when these pesky rodents arrived.   Next, producer Meagan Cantwell talks with Contributing Correspondent Ann Gibbons about what has happened in the 50 years since anthropologists found Lucy—a likely human ancestor that lived 2.9 million to 3.3 million years ago. Although still likely part of our family tree, her place as a direct ancestor is in question. And over the years, her past has become less lonesome as it has become populated with other contemporaneous hominins.   This week’s episode was produced with help from Podigy.   About the Science Podcast   Authors: Sarah Crespi; Meagan Cantwell; Ann Gibbons LINKS FOR MP3 META   Episode page: https://www.science.org/doi/10.1126/science.z4scrgk   About the Science Podcast: https://www.science.org/content/page/about-science-podcast Learn more about your ad choices. Visit megaphone.fm/adchoices