Although some of the simplest stone tools may not look like much more than broken rocks, they were remarkably effective for cutting through meat and cracking open bone. Modern experiments with stone tools similar to these have demonstrated that an animal the size of an elephant can be readily butchered with such implements. Tools of various shapes and sizes have been found at several different sites in the Atapuerca region.

A Diverse Tool Kit
Archaeologists classify stone tools into several different modes, according to how they were made. The stone tools found at the Atapuerca sites can be grouped into three modes. The earliest style, called Mode 1, can be traced back 2.5 million years, to the first stone implements made by hominids in Africa. Mode 2 emerged around 1.5 million years ago in Africa and about 300,000 years ago, Mode 3 developed in Europe and Africa.

Each new mode represents an increase in sophistication. Mode 1 tools (right top) are often just stone cobbles that were hit one or two times with another rock to knock off flakes of stone and produce sharp edges on both the cobble and the flake. Tools classified as Mode 2 (right center), however, were typically struck repeatedly on both sides with stone, bone or antler and often have a symmetrical teardrop shape. The humans who made Mode 3 tools (right lower) carefully shaped a stone core, usually with a soft material like bone or antler, so that a single blow could detach a partly or fully finished cutting tool. Such tools tended to be sharpened repeatedly, gradually changing their shapes.