Beth Shapiro, Professor of Ecology and Evolutionary Biology at UCSC will describe recent work using ancient DNA to reveal the timing and cause to two Holocene extinctions. Mammoths are perhaps the most famous of the extinct Ice Age megafauna, but the cause of their disappearance is still debated. Using DNA preserved in dirt (in combination with other paleoecological proxies) Dr. Shapiro will describe precisely when and why the mammoth population of St. Paul Island, Alaska, went extinct. In contrast, 19th century over exploitation by human hunters led to a reduction in passenger pigeons from billions to dozens in less than 40 years. Using high coverage complete genome sequences from four museum specimens of passenger pigeons, we explored how living in such large populations may have made this species more susceptible to extinction once their population crashed.