A prior indigenous technological species might have arisen on ancient Earth or another body, such as a pre-greenhouse Venus or a wet Mars. That's the focus of a paper by Penn State University's Dr. Jason T. Wright, an associate professor in astronomy and astrophysics. Published this week in arXic, "Prior Indigenous Technological Species" is based on Wright's idea that an ancient species inhabited Earth and possibly one or more other planets in our solar system billions of years ago. Those species may have come from outside the solar system, but he also addresses the possibility that they originated on Earth. So where are they now? And if they're gone, where's the evidence that they were here? The question is not how long the past we might be able to detect the fossil remains of the species—we don't know how to measure intelligence reliably from fossils of bones—but to detect unambiguous technosignatures. Wright rightly points out that fossils, tools, living shelter and other