What it's like to shake hands with a 2 million-year-old ancestor

A fossil site on the shores of Lake Victoria in Kenya has revealed 2.9 million year old stone tools that were used by early human ancestors to butcher hippos and process tough plants into food. These are among the oldest stone tools ever found.

The tools were discovered at a site at Nyayanga, Kenya, along with two molars from Paranthropus, a hominid species that is on another branch of our human evolutionary tree.

Finding tools, animal remains with tool marks on them, and hominid remains all at the same site is a tantalizing hint that this early stone tool technology was more widely used than we thought. 

Known as the Oldowan tool kit, examples of this kind of early stone tool technology have been found across central Africa in Kenya, Tanzania and Ethiopia and into the Middle East, Europe and Asia. The tools get their name from discoveries by Mary and Louis Leakey who, beginning in the 1940s, explored the Olduvai Gorge in Tanzania.

The couple found remains of several species of human ancestors, including Homo habilis, or "Handyman," from around two million years ago, who were at that time considered to be the first tool makers. They are also on a direct evolutionary line to Homo sapiens — our species. But we know that Paranthropus was more than half-a-million years older.  

At first glance, the stones don't look like tools, as I discovered during my visit to the Olduvai Gorge in 1980. A local guide showed me a box of artifacts believed to have been used by Homo habilis.

I looked into the box and said, "How do you know they are tools? They look like ordinary round stones that have been picked out of a river."

The guide smiled politely and replied, "They probably were picked out of a river, but look closely and you will see that one side is rounded but the other side has been chipped away into a sharp edge. It could have been used as a chopping tool to cut meat off a bone."

The stones were shaped into cutting tools by hitting them with other stones.

He took one of the tools out of the box and handed it to me.

"Here, hold onto it, and you will see what I mean."

I held the stone in my hand with the rounded part in my palm and sharp edge facing up. The guide turned my hand over and moved my arm up and down in a chopping motion to give me the idea of how it worked.

The weight of the stone gave my arm more power, and the cutting edge could strike with considerable force. It appeared that stone had been carefully chosen for its shape, so the round part fit comfortably in the hand.

A variation on the simple chopper, found in other locations, is a flake — a stone struck in just the right way so a large chip comes off, with sharp edges that can be used as a knife. These tools took considerable skill to make.

Suddenly I was struck by a profound thought. This ancient tool I was holding fit perfectly into my hand. I felt a direct connection to someone, or some creature, who used that exact same tool in this same place two million years ago to make dinner.

The stone became a bridge crossing the vastness of time. I felt like I was shaking hands with an ancestor 200,000 generations ago. Never have I felt such a direct connection to the past. 

Our ability to fashion tools over the last three million years has enabled humans to become a super-species as we moved from stone to iron, bronze and steel. They allowed us to not only occupy every niche on the planet, we even managed to leave it.

During the last mission to the moon in 1972, Harrison Schmitt, the only scientist to go there, used a hand-held camera to snap an iconic photo of the whole Earth. Astronauts today don't get that global view because the International Space Station is only about 400 km up — too close to see the whole planet. Any picture of the whole Earth today is taken by satellite. 

So Schmitt's photo is the last image of the Earth taken by a human hand — and how appropriate that right in the centre of the photo is Africa, where tool-making began?

How far we have come with devices we hold in our hands. And if you are reading this blog on a smartphone, think about how much farther our tool making has come since that Earth photo was taken in 1972.