“[We found] two interlocking logs joined transversely by an intentionally cut notch,” Barham and his colleagues wrote in a 2023 study published in Nature. “This construction has no known parallels in the African or Eurasian Palaeolithic.” Older worked wood does exist, with the earliest known example being a fragment of polished plank from the Acheulean site of Gesher Benot Ya’aqov in Israel that’s more than 780,000 years old. But a plank is a single object. At Kalambo Falls, someone shaped two logs to fit together, which is the first evidence anywhere of wood used to build something.
For decades, wood seemed to play only a bit part in hominin toolkits: a shaft for a spear, a handle for an ax, or kindling for a fire. Ancestors like Homo erectus were cast as nomads who were unlikely to build anything intended to last. So who notched the Kalambo logs? No one knows. H. erectus, who lived from 2 million to 100,000 years ago, is the obvious suspect. Homo heidelbergensis is another, since a skull from that species has been found elsewhere in Zambia. And at Florisbad in South Africa, modified wooden objects turned up in spring deposits alongside the remains of a later species, Homo helmei.