'When I First Saw It, I Thought This Can't Be Real'

Archaeologists have uncovered what is thought to be the world's oldest known wood structure, whose estimated age suggests woodworking is at least 175,000 years older than our species. A research team discovered five very old pieces of wood in waterlogged sediment near Zambia's Kalambo Falls in an area that has previously given up wooden artifacts and stone tools. Through luminescence dating—a method used to determine when trace amounts of radioactive isotopes in sediments were last exposed to sunlight or heat—archaeologists determined that one cut log and a tapered piece of wood were 324,000 years old, a digging stick was 390,000 years old, and a wedge and two interlocking logs were 476,000 years old, per Live Science.

Archaeologists found evidence that stone tools were used to form a U-shaped notch, allowing one log to lie on top of the other at a 75-degree angle. "When I first saw it, I thought this can't be real," University of Liverpool archaeologist Larry Barham, lead author of a study published Wednesday in Nature, tells the Guardian. There are "no known parallels in the African or Eurasian Palaeolithic," a period that spans millions of years up to about 12,000 years ago, according to the study. Researchers suggest the structure was part of "a raised platform, walkway or foundation for dwellings" in a "periodically wet floodplain." You might expect Homo sapiens to be able to build such a structure. But it's believed Homo sapiens didn't emerge until 300,000 years ago. Homo heidelbergensis roamed the region nearly 500,000 years ago.

It was previously thought that these early humans were nomadic foragers without much technological skill. But "the wood and the stone suggest a high level of ingenuity, technological skill and planning," Barham tells the Guardian. And "the rarity of wood preservation implies that such behaviors were more widespread than what we witness in the archaeological record," adds Annemieke Milks, an archaeologist at the University of Reading, who was not involved in the study. Researchers were impressed by the other wood artifacts as well. A split branch with a notch might have formed part of a trap, while a log cut at both ends "might be a work surface," speculates Barham, who is working to get Kalambo Falls classified as a UNESCO world heritage site. (More discoveries stories.)