Volcanic glass and Stone Age sailors
In a coastal cave in southeastern Greece, small, sharp, black stones change our understanding of human technological history. Franchthi Cave, overlooking the Kiladha Bay in Argolis, holds a nearly continuous record of human occupation for about 35,000 years. Within its layered deposits of soil and rock, archaeologists found flakes of obsidian, a natural volcanic glass. Chemical analysis confirmed their origin: the island of Melos, part of the Cyclades island chain.
The trip from Melos to Franchthi Cave is approximately 150 kilometers (about 93 miles) across the open Aegean Sea. Geologically, Melos has always been an island, never connected to the mainland even when sea levels were 120 meters lower during the last ice age. The oldest pieces of this obsidian appear in layers dated to the Upper Paleolithic, around 13,000 BCE. This places purposeful, planned seafaring in the Mediterranean thousands of years before the start of agriculture. The people who brought this material to the cave were hunter-gatherers, not farmers, and they possessed the skills to build and navigate watercraft across significant stretches of open water.
Rewriting the timeline of technology
The presence of Melian obsidian at Franchthi shows that complex maritime activity is much older than previously thought. The conventional model of prehistory suggests that farming, established in Greece around 7,000 BCE, was a prerequisite for such technological and social organization. The obsidian tools found in much older layers disrupt that timeline. These were more than a few accidental pieces; obsidian use increased substantially through the Mesolithic period (around 9,000-7,000 BCE), indicating regular and established contact with Melos.
Obsidian was highly valued for its sharp cutting edge, which can be finer than a modern surgical scalpel. The inhabitants of Franchthi used it to make blades and other tools. The voyages to acquire it would have been complex undertakings. The craft used are unknown but may have been reed boats or dugout canoes. Navigators would have needed to plan multi-day trips, contend with weather, and likely travel between islands as waypoints. The effort involved suggests a society with advanced planning, communication, and a deep understanding of its environment. This evidence from Franchthi Cave shows that long-distance interaction networks and sophisticated travel existed deep in the Stone Age.