A study in the journal Nature reports the discovery of a wooden structure dating back 476,000 years near Kalambo Falls, in Zambia. The structure predates the evolution of Homo sapiens by more than 120,000 years. Archaeologists found two preserved interlocking logs joined side-to-side by an intentionally cut notch. Tool marks were found on both logs, along with a collection of wooden tools. The study authors believe that the logs may have been used to build a raised platform, walkway or foundation for a dwelling in an area subject to periodic flooding. The discovery challenges the view that Stone Age hominini were nomadic. To estimate the age of the logs and tools, the team used luminescence dating techniques that roughly calculates the last time minerals in the sand surrounding the items were exposed to sunlight.