About a quarter century ago, a 1.8-million-year-old skull fossil was discovered in the republic of Georgia that eventually wound up altering scientific consensus on humans' earliest known ancestors to venture outside of Africa.

Today, the site where those fossils were found remains a treasure trove of evolutionary history.

Paleoanthropologist David Lordkipanidze led the excavation of the Georgia site, known as Dmanisi. Based on a haul of fossils, including Skull 5, an astonishingly complete skull of an adult male, an international team of scientists led by Lordkipanidze eventually concluded that all early fossil humans belong to the same species, Homo erectus. Their findings ran against the prevailing view that several species existed in the Pleistocene.

September 24 marks the anniversary