Early stone tools

For a long time it was thought that the use and manufacture of tools are features that distinguish us humans from all other species. But today we know that many species of animals use objects from their environment for different purposes, and some can even make tools by modifying these objects for particular purposes. Some primate species are among the most skilled and flexible tool users. The most diverse and largest tool repertoire has been observed among chimpanzees. So it is assumed that our ancestors that lived 3-4 million years ago, probably also used stones, sticks and twigs to better exploit various savanna food sources. However, we can only speculate on this because these tools leave no lasting traces.

New caledonian crows are among the most intelligent bird species. They can flexibly make tools out of twigs and use them for getting food.

Chimpanzees use many different types of tools for many different types of purposes. Chimpanzees and other great ape species have good skills to perceive and understand their physical environment. They understand that certain objects have certain properties, and how these can be used for particular purposes.

Tool making and human evolution

But archeological findings indicate the apperance of a new kind of tool in Africa about 2.6 million years ago: manufactured stone tools with sharp cutting edges. There is evidence that such tools were used by Australopithecines as early as 3.4 million years ago.

The survival and reproduction of the hominins living at that time probably depended a lot on getting enough animal food. Thus, there was a high selection pressure on the use and processing of objects in order to better exploit these food sources, such as for separating the meat from the carcass, breaking up bones, and warding off predators. With manufactured stones that had sharp cutting edges, more food could be obtained more efficiently than “with bare hands” or other parts of the body. Probably representatives of Homo habilis were the manufacturers of these first stone tools.

The production of these stone tools seemingly already differed in some ways from the production and use of tools we can observe among chimpanzees today: one object (the hammerstone) was used to work on another object. It already requires higher coordination of hands and increased patience to make a useable stone flake of certain quality.

In addition, the production and use of tools among primates is learned in the course of a lifetime by observation and imitation of conspecifics as well as individual trial-and-error learning. Behavioral biologists call this form of learning “social learning”. The more complex the tools and their manufacture, the better must be the skills for social learning so that a specific toolmaking culture can spread in a population and be passed on to offspring

2.6 Million year old Oldawan culture stone tool

 

Anthropologists have taught the Bonobo Kanzi to make such Oldowan stone tools in order to test the ability of our closest relatives for making these tools. Kanzi is able to make and use these stone chips, but apparently he is not quite as skilled as the makers of the oldest Oldowan stone tools. These must have already had an improved control of hand movements and endurance than chimpanzees and bonobos.

Questions about the video:

Questions about the video:

Compare the toolmaking and tool use by chimpanzees in the wild (e.g., termite fishing using prepared branches) to Kanzi making / using the stone toolin the video:

Causal map on the evolution of tool making

The environmental conditions of the savanna were increasingly such that those hominins had higher chances of survival and reproduction that could exploit animal food sources. Among those who fed on animals, those had higher survival and reproductive opportunities, which could effectively exploit as much meat as possible with the help of tools. Better tools for exploiting meat and bone marrow, and thus higher chances of survival and reproduction, had those who had increased cognitive abilities for the production of these tools. These include patience, the ability to coordinate hand movements, and the ability to select suitable objects from the environment for tool making. In addition, those had better tools who could learn to make these tools from others in their group through social learningGenes involved in the development of these skills were inherited to their offspring, who also had better chances of survival and reproduction because of their ability to make effective tools.

Further reflection questions:

Possible extension of the causal map to include the role of the social/cultural environment in the development of specific tool making/tool use skills, as well as the natural selection of body features that facilitate the making and use of stone tools

References