How chimpanzee tool use provides insight into early human behaviour

Since Jane Goodall's groundbreaking discovery in 1960 that chimpanzees in Gombe Stream National Park in Tanzania use tools to fish termites out of their mounds, further research has found that they use a variety of different tools to suit specific purposes.

Chimps have been found to use longer sticks to probe tree ant colonies, rocks as hammers to open fruit, and big sticks to wave around and throw like weapons to ward off intruders.

In March, researchers from the University of Oxford studying in the same region published a study in the online journal iScience showing that chimps also apply engineering skills by choosing materials with specific mechanical properties to use as tools.

Termite mounds, for example, involve tunnels that curve in different directions. When the researchers examined which plants the chimps selected out of all those available, it was the more flexible twigs that were fashioned into probes to negotiate the tunnels and capture more food. 

And the more rigid plants nearby? They were never chosen by the chimps, suggesting they have some sort of an intuitive understanding of material properties to help them craft the best tools for the job.

In engineering terms, the chimps are selecting materials for strength and flexibility depending on the application. The same principle is used when designing structures such as a bridges, which need to be strong enough to carry the load, yet light weight and flexible enough to absorb vibrations from traffic and wind.

Tool making requires thought and decision making. It's also a skill that is passed down through generations, as young chimps watch and imitate their parents to learn how to use the tools.

Tool use has been found throughout the animal kingdom, from crows, otters, octopi, and as you will hear on this episode of Quirks & Quarks, even fish. 

Humans have definitely been demoted as the only toolmakers.

When it comes to our human ancestors, most tools we find are made of stone, with the oldest found in Kenya dating back 3.3 million years. These early tools, possibly used by Homo habilis (which means "handy man") were made by simply hitting two rocks together to get a required shape, such as a pointed edge to use for chopping. 

Over time, stone tools became more complex, still using two stones, one to become the tool, the other a hammer to either chip away an edge of the tool to become a scraper, or strike off small sharp flakes for cutting. 

But it raises the question of how many other tools our ancestors made that were not made of stone. Did they apply the same engineering skills as chimpanzees to fashion tools out of wood? Unfortunately, wood does not preserve well in the fossil record. The oldest wooden tools found in Zambia are much younger, made 476,000 years ago by Homo sapiens. 

However, there is one tool fashioned from bone that has been dated to 1.5 million years ago, suggesting our distant ancestors did use other materials.

Take a look in your kitchen drawer at all the different tools and the materials they are made from. You may have a stainless steel carving knife beside a plastic spatula. Perhaps Homo habilis carried an equally varied tool kit made of a variety of materials, each suited to a different purpose. 

We may never find the answer to that question, but perhaps chimpanzees can provide some insight.