Mad about Science: Kalambo falls building site

By Brenden Bobby
Reader Columnist

Science: just when you think you’ve got everything figured out, new evidence comes to light that says: “You don’t know squat!”

This happened recently at the Kalambo Falls prehistoric site. British archaeologist John Desmond Clark first excavated the site on the border of Zambia and Tanzania in East Africa in 1956. The location became a national monument in 1964, which led to its preservation and protection. More recently, researchers discovered a wooden building structure estimated to be at least 476,000 years old. This is pretty remarkable for a number of reasons.

Wood is an organic material that decays relatively quickly on a geological timescale. Fossilization of wood requires very specific conditions, which don’t often occur in places where humans settle. It is also one of the most plentiful and useful resources that humankind has ever used. This has created a massive gap in the fossil record, which has left archaeologists to assume things based on a lack of evidence.

In the case of the Kalambo Falls building site, it’s believed that a high water table and fine sediment worked to inhibit decomposition processes, preserving these artifacts for hundreds of thousands of years.

We have a very clear record of stone tools being used as far back as 2.6 million years ago. There is secondary evidence of wooden spears being used 500,000 years ago, but it wasn’t believed that hominins were using wooden tools for building until much more recently — sometime within the past 20,000 years. Recent findings at the Kalambo Falls prehistoric site completely uproots that assumption.

An ancient tool found at the site. Photo courtesy Professor Larry Barham/University of Liverpool.

Based on the remains of the structure, it is apparent that wooden tools were used to shape the wood; most notably cutting a notch in the structure to secure portions of the building together. At 476,000 years old, this structure predates Homo sapiens by at least 170,000 years. Whether this was the work of Neaderthals or another group of early hominins has yet to be determined, as none of their physical remains have yet been excavated from the site.

It had been believed that hominins of this period were almost exclusively nomadic, packing up their structures and transporting them wherever the groups went. The presence of what appears to be an intentionally permanent structure completely upends established beliefs about social organization at this time, as well as the technological capabilities present in the Pleistocene epoch.

The original intent of this structure has yet to be theorized. It’s likely that it was used as a platform over a stream or river, either for structures or for the people of this settlement to perform their daily chores near the water more safely. 

Throughout human history, running water has been an intersection of necessary survival and lethal danger. Tropical climates in particular have especially dangerous waterways that are filled with large predators and year-round heat that fosters the growth of bacteria and disease. The historic danger of water has led to the formation of a number of cautionary mythologies around the world, including the Kelpie of Gaelic origin and the Kappa of Japanese folklore — creatures that are said to inhabit waterways and are eager to drag unsuspecting people to their doom.

The timeline of this structure seems to coincide with a period of warmth in the Kalambo Falls area. This trend led to more abundant tree growth and frequency of flooding, which seems to be backed up by the discovery of this support structure and its Stone Age creators’ intention to build elevated structures off the floodplains. 

This abundance of woody material also likely contributed to the use of wooden tools, which is supported by the number of digging and carving implements that have been recovered from the site.

Though it’s difficult to say exactly when the wooden and stone tools were paired with the discovery of hafting — or fusing a stone cutting implement with a wooden handle or haft — the discoveries here work to narrow the timeline. Hafting would eventually lay the groundwork for construction of more advanced tools and weapons, particularly axes, which remain one of our most useful tools — just ask anyone around with a wood stove.

These discoveries present more interesting food for thought, in that they redefine our understanding of how our early ancestors viewed the world around them and solved problems. It shows a dramatic similarity to how we approach and solve problems today, and underscores the vast gulf of time during which humans and proto-humans could imagine something such as a platform or a building while it was still a pile of stones or a thicket of trees. 

Ingenuity and imagination are perhaps our oldest and most valuable tools, and these finds support that.

The Kalambo Falls artifacts are also an incredible display of how science and our perception of history can change based on the emergence of new evidence. Something as simple as notched logs can reorient our entire scope of thinking and alter our preconceived notions.

Stay curious, 7B.