Research into very, very old DNA has made huge leaps forward over the last two decades. That has allowed scientists like Beth Shapiro to push the frontier further and further. "For a long time, we thought, you know, maybe the limit is going to be around 100,000 years [old]. Or, maybe the limit is going to be around 300,000 years," says Shapiro, Professor of Ecology & Evolutionary Biology at UC Santa Cruz. "Well, now we've been working with a horse fossil in Alaska that's about 800,000 years old." Beth's career has spanned the heyday of ancient DNA research, beginning in the late 1990s when rapid genetic sequencing technology was in its early days. She talked with Short Wave co-host Aaron Scott about the expanding range of scientific puzzles the young field is tackling — from new insights into our Neanderthal inheritance to deep questions about ecology and evolution.