If researchers could go back in time 100,000 years, they’d find at least three different types of humans walking the Earth. Today, only the dominant group, Homo sapiens, survives. The scientist Johannes Krause explains how new discoveries in paleontology and genetics help pinpoint the exact period in which human groups interbred. Understanding this timeline, he says, brings us closer to understanding what makes modern humans unique. Further reading: “Earliest Modern Human Genomes Constrain Timing of Neanderthal Admixture,” by Johannes Krause, et al. “Neanderthal Ancestry Through Time: Insights From Genomes of Ancient and Present-Day Humans,” by Leonardo N. M. Iasi, et al.“DOGE Is Failing on Its Own Terms,” by David Deming Interview with Svante Pääbo, 2022 Nobel laureate in physiology or medicineGet more from your favorite Atlantic voices when you subscribe. You’ll enjoy unlimited access to Pulitzer-winning journalism, from clear-eyed analysis and insight on breaking news to fascinating explorations of our world. Subscribe today at TheAtlantic.com/podsub. Learn more about your ad choices. Visit megaphone.fm/adchoices