We tend to think of the overuse of natural resources, climatic instability, and large-scale human land use as quintessentially modern day problems. Yet a group of researchers led by archaeologists and calling themselves historical ecologists have recently come together to determine what we need to know about past human-environmental relationships to build a more sustainable future. These historical ecologists crowd-sourced hundreds of research questions from scholars around the world that, when answered, will reveal key information about how people have hade impact on and responded to changing environments over the course of thousands of years. Workshops were held at Uppsala University (Sweden) and Simon Fraser University (Canada) to discuss submissions from scholars and identify the 50 questions that are most in need of answering. The list of 50 priority issues for historical ecology will be published Friday in the open access journal PLOS ONE.