Since the 1970s, Poulianos has investigated early hominid remains found in a cave near Petralona, Greece, and has become known for controversial claims over their age. According to Poulianos, the Petralona Cave was accidentally discovered in 1959 by local villagers searching for a spring in the mountainside. The Petralona skull, specifically, was discovered in 1960 when it was removed from a rock in the cave. Early estimates at the time placed the age of the hominid remains to around 70,000 years old. Poulianos would ultimately study the remains, name the hominid "Archanthropus europeaus petraloniensis", and estimate its age to be around 700,000 years old.