The teardrop-shaped hand-axes date to about 1.76 million years ago, and would have been used for a range of tasks from chopping wood to cutting up meat. They would have been so useful in fact that scientists describe them as the Swiss army knife of the Stone Age. Researchers tell the journal Nature that the tools were probably made by the human ancestor Homo erectus. This was a bigger-brained, smarter and more dextrous creature than any human species before it. Homo erectus ranged across Africa and Asia before going extinct about 70,000 years ago. Many suspect it was on the direct evolutionary line to modern humans - Homo sapiens. Palaeolithic stone tools can be grouped into a number of different styles. BBC