The answer to that question has just changed to at least 80,000 years older than previously thought – based on obsidian-crafted tools found 100 miles from source. Excavations of the dry bed of the ancient Lake Olorgesailie, in southern Kenya, led by American paleoanthropologist Rick Potts, suggest that our ancestors created the first supply chain between 305,000 and 320,000 years ago, at least 80,000 years older than we previously thought.