Archaeologists have discovered the oldest evidence of artificial structures made of wood, dating back almost half a million years – predating the appearance of our own species and suggesting our relatives settled down much earlier than we thought.

The discovery was made at the archaeological site of Kalambo Falls in Zambia, where archaeologists found two logs joined together in an almost cross-like shape. Clear cut marks from stone tools were found on the wood, indicating they had been deliberately cut and crafted into this structure. Exactly what its purpose was remains lost to time, but the scientists speculate that it could be part of a foundation for a platform or shelter.

To determine how old the structures are, the researchers used a technique called luminescence dating. This method allows scientists to calculate when a sample was last exposed to sunlight, indicating how long it has been buried and, as such, a minimum age. When they performed this on minerals in the sand in which the logs were buried, they came up with an astonishing number – around 476,000 years old, placing it in the early Stone Age.

Previous finds have shown that early humans were making tools, weapons and other instruments out of wood even earlier, but this marks the oldest known evidence of construction with the material. In fact, it predates the existence of Homo sapiens as a species, which is thought to have evolved around 300,000 years ago. The researchers don't speculate on which species might be responsible, but many of our ancestors and relatives were plodding around Africa at that time, including Homo erectus and Homo heidelbergensis.

One of the main reasons we don't often see wood that old is obvious – it just doesn't last very long. The archaeological site at Kalambo Falls helps preserve these organic materials for longer thanks to its high water levels.