In the rocky landscape of Dmanisi, Georgia, a quiet archaeological dig launched in 1991 became the site of one of the most important discoveries in paleoanthropology: Skull 5 (D4500). Unearthed in 2005 and formally analyzed in 2013, this remarkably well-preserved fossil is nearly 2 million years old, dating back to the early Pleistocene. It remains the most complete adult hominin skull ever found from that time period.
What makes Skull 5 extraordinary is the combination of features it displays. Despite having a small braincase—only around 546 cubic centimeters, comparable to much older hominin species—its owner possessed a fully modern human-like body, capable of long-distance walking and tool use. This surprising mix of primitive and advanced traits challenged long-held ᴀssumptions about how early humans evolved and migrated.
Before the Dmanisi finds, most scientists supported the “Out of Africa I” model, which suggested that Homo erectus evolved in Africa and only migrated out much later. But Skull 5, along with other remains from Dmanisi, provided solid evidence that early humans had already left Africa by at least 1.85 million years ago—much earlier than previously believed.
Even more groundbreaking was what Skull 5 revealed about variation within a species. Traditionally, fossils with differing shapes were often classified as separate species. However, the Dmanisi hominins showed a wide range of features, yet came from the same location and time period, suggesting they may all belong to a single, diverse species: possibly Homo erectus, or what some now call Homo erectus georgicus.
This single fossil and its companions have reshaped how we define species in our ancestral tree, blurring the lines between categories and showing that diversity was a normal part of early human evolution.
Today, Skull 5 is housed at the Georgian National Museum in Tbilisi, and it continues to be a centerpiece in debates over human origins. From a quiet hillside in the Caucasus to global headlines, this fossil reminds us that our journey as humans has always been complex, surprising, and deeply interconnected.
