World's oldest wooden structure defies Stone-Age stereotypes

Archaeologists dug into a riverbank in Zambia and uncovered what they call the earliest known wood construction by humans. The half-million year-old artifacts could change how we see Stone-Age people. Larry Barham and Geoff Duller/University of Liverpool hide caption

toggle caption Larry Barham and Geoff Duller/University of Liverpool

Archaeologists dug into a riverbank in Zambia and uncovered what they call the earliest known wood construction by humans. The half-million year-old artifacts could change how we see Stone-Age people.

Larry Barham and Geoff Duller/University of Liverpool

The find didn't look like much at first – basically a log, lying crosswise over another log.

"It didn't look particularly exciting," says , professor of archaeology at the University of Liverpool. "But when you look closely and you remove the sand around it, you can see where one sits on top of the other is a notch."

That notch suggested that the logs had been manipulated by human beings – extraordinarily ancient ones, who once frequented this site above the dramatic 772-foot Kalambo Falls in Zambia.

Later analysis of the logs would reveal telltale signs of having been cut, chopped and shaped by human tools.

– stretching back some 476,000 years.

Wood in the Stone Age

We know very little about how early humans worked with wood because so few of the artifacts survive. Previous discoveries have been limited to small, portable tools and somewhat ambiguous wood scraps.

But at sites like this riverbank excavation, where artifacts stayed submerged under water and clay for millennia, some fragments can survive. The , spanning multiple institutions and spearheaded by Barham, set out to find these wood artifacts in order to shed light on the behaviors and capacities of our ancient ancestors.

An archeologist holds up a piece of ancient wedge-shaped wood that was excavated near the Kalambo river in Zambia. Larry Barham and Geoff Duller/University of Liverpool hide caption

toggle caption Larry Barham and Geoff Duller/University of Liverpool

"These wooden artifacts, though, are really, really fragile," says , curator of archaeology at the Livingstone Museum in Zambia and one of Barham's collaborators. "Once they're removed from their natural ground, where they were being preserved, they start disintegrating. You might even lose it."

, not nearly old enough. So the team used luminescent dating technology on the sediment grains adjacent to the wood, which can estimate when the sun last shined on this spot. They found three different periods of human occupation: 476,000, 390,00 and 324,000 years ago.

That would place this site well before the evolution of homo sapiens, thought to have emerged around 300,000 years ago.

Were hominins more settled than we thought?

Those ancient hominins, such as homo erectus and homo heidelbergensis, were thought to have been nomadic hunter-gatherers. But the new site suggests that they may have hung around certain areas where it was relatively easy to make a living.

"The thoughts were that these people were moving from one place to the next. But a structure sort of denotes permanence," says Katongo.

Researchers work on the excavation of an ancient wooden structure. Larry Barham and Geoff Duller/University of Liverpool hide caption

toggle caption Larry Barham and Geoff Duller/University of Liverpool

That seeming permanence, in turn, is leading researchers to rethink some long-held preconceptions about early human beings.

"I would say we need to consider these humans as having the ability to abstract forms from the environment and make them happen, and to pass [that knowledge] on through generations," says Barham. "And that's opened my mind to these pre-sapiens hominins being capable of what we would think of as quite complex behavior."

Barham even argues that the complexity of these technologies might have necessitated some form of spoken language – again, far earlier than conventional wisdom holds.

For Maggie Katongo, this finding refutes stereotypes about human ancestors.

"When we make reference to these hominins we always perceive them as primitive. But from the technology that we've been able to discover at the site, you see how sophisticated these hominins were."

An important find for Zambia

Katongo says the Deep Roots Project, with its extensive incorporation of local research talent, is creating a new model for archaeology in Africa.

. I'm excited about that and I hope this really does push that agenda."