Study of the tools and production methods of 2.5 million years ago holds the key to understanding modern technology
The way in which technology has developed over the past 2.5 million years is one of the most fascinating aspects of the study of human evolution. Technology is the only trait exclusive to human beings. An analysis of the stone tools made by hominids of the Pliocene-P0leistocene and Pleistocene era between 2.5 million and 10,000 years ago can provide us with valuable information about the social and cultural complexity of human communities over time.
Just as DNA sequences hold all our biological information, the sequences of rock-flake reduction represent the extra-somatic sequencing of the development of human culture and technique. Studying these kinds of materials at the Sierra de Atapuerca sites near Burgos, Spain, covering a period of the past million years, has provided us with a unique opportunity to see just how tools were made and used in prehistoric times.
We are using a logical system to study the production sequences of these man-made objects. First, we look at how they are conceived and transformed. We then evaluate the geometrical shapes that are obtained when they are made. In order to do this, we break down the edges of the tools to a trigonometric model and calculate their use capability. We have devised four basic shapes: dihedral, trihedral, semi-trihedral and pyramidal. Each of these models allows us to also gauge the efficiency of the tools.
We analyse the tools using high-resolution technology. Petrological analysis by means of thin sections and X-ray diffraction allows us to work out the physical and chemical composition of the materials and where they are from. This throws light on the capacity of the Pleistocene hunter-gatherers to select materials.
Using the scanning electron microscope, we can observe the microstructural deformations due to use, that is, how the crystal networks of rocks are deformed when used for specific tasks. Similar materials are put through controlled mechanical tests to determine their response to work, and these are compared with the prehistoric originals to uncover their uses.
We use this data to trace human organisation from the hominids of the lower Pleistocene age, such as Homo antecessor, who inhabited Europe 800,000 years ago and who used dihedral edges and did not make large tools, to Homo heidelbergensis, alive 300,000 years ago, who used large tools that combined dihedral with trihedral and pyramidal shapes. These are multifunctional tools used for working with skin, wood and meat.
Thanks to the analysis of the morphological and technical structures of lithic objects and their uses, current studies point to the existence of a technological revolution in Europe that began about 500,000 years ago and became systematic about 300,000 years ago. The use of axes and cleavers is largely responsible.
There can be no doubt that the study of the tools and production techniques of prehistory are basic to an understanding of the way present-day techniques and tools have developed. At the same time, this proves that most modern technical behaviour has its roots in the distant past. It is this set of biological and technical acquisitions that has given rise to the cultural make-up of the human race. If we accept that technology has made us what we are, we still need to prove that we are capable of putting it to good use, in a fearless and responsible fashion.
Eudald Carbonell is co-director of the Atapuerca Project and professor of prehistory, Rovira i Virgili University, Tarragona, Spain.