So the next time you pass a jewelry shop window displaying a beautifully cut teardrop shaped stone, don't be so sure it's just your culture telling you that that sparkling jewel is beautiful.

These crude tools were around for thousands of centuries, until around 1.4 million years ago when Homo erectus started shaping single, thin stone blades, sometimes rounded ovals, but often in what are to our eyes an arresting, symmetrical pointed leaf or teardrop form.