In The Extratempestrial Model, Dr. Michael P. Masters posits that UFOs and "Aliens" are our future human descendants, coming back through time to visit and study their own hominin evolutionary past.
As a professor of anthropology, Masters uses an abductive approach to logically infer the best explanation. He examines well-documented abductee experiences in the context of this time travel model, and considers other theories put forth to elucidate this complex and mysterious phenomenon.
While no single model can account for all aspects of these encounters, in considering various contact cases across the world and through time, recurrent patterns emerge that may offer insight into what these objects are, who is inside, and from where-or potentially when-they are coming.