“We can probably assume that wooden tools have been around just as long as stone ones, that is, two and a half or three million years,“ he said. “But since wood deteriorates and rarely survives, preservation bias distorts our view of antiquity.” Primitive stone implements have traditionally characterized the Lower Paleolithic period, which lasted from about 2.7 million years ago to 200,000 years ago. Of the thousands of archaeological sites that can be traced to the era, wood has been recovered from fewer than 10.