Human etchings half a million years old?

The uncertainty of science: Did an ancestor of humanity etch zig-zags on a shell half a million years ago?

This story is a fascinating illustration of the difficulties of pinning down facts in the field of science. The researchers do an impeccable job of checking all possibilities, and finish by cheerfully admitting that their conclusions could be wrong. If right, however, the discovery is significant, as it tells us that 500,000 years ago an ancestor of the human race was capable of drawing an abstract design on the surface of a shell.