As the fossil record continues to grow, it presents us with information on the bones and teeth of our ancestors. From these, scientists can figure out how tall and heavy our ancestors were.
But what if we could tell not only how large a species’ hands were, but also suggest what they used them for? Looking at the sometimes fragmentary remains of early hominids, this might sound like the ultimate Mission: Impossible.
Not quite. Many scientists are keen on reconstructing past behavior, and there are several ways in which we can try to do so by working with what we know.
Consider your own actions, say earlier today. When you left your home this morning, you might have placed a cup and a plate in the kitchen sink, thinking that you would do the dishes later.
What if you never came back? The cup and the dish would be a clue that you had eaten, and where. Better yet, a chemical analysis of the residue in your cup could identify what you drank.
Similarly, the behavior of our ancestors who made artifacts – traditionally a role reserved for members of the genus Homo – can also be reconstructed. They have left many traces of their own.
For example, the earliest artifacts made by humans that are still retrievable today are stone tools. They represent a kind of fossilized human behavior that can tell us a lot about the capabilities of the species who made them.
Different kinds of tools require different levels of skill to manufacture. The earliest tools were extremely simple; most of us could reproduce them today. Pick up two river pebbles, smash them together a few times and voilà: you have an Oldowan chopper (as these oldest-known tools are called).
If you want to replicate a hand axe or one of the even more complex stone tools used by our immediate ancestors, things get a little more complicated. Instead of just a few intermediate steps, dozens – if not hundreds – of these steps had to be taken to get to the finished product.
Each step along the way reflects our ancestors’ behavior. The increasing complexity of stone tools implies a growing intelligence and the ability to teach the next generation how to make tools. Sourcing stone tools tells us where the materials came from. That information, combined with the location where the tools were found tells us how far these hominids moved across the landscape.