New Scientist is carrying this article summarizing the potential discovery of "compound machine" use by humans far earlier than previously thought, in China:

Distinctive spiral patterns carved into a small jade ring show that China was using complex machines more than 2500 years ago, says a Harvard graduate student in physics
...
"I said I bet you could do it with a modified bow drill, and she [Jenny So, an art historian at the Chinese University of Hong Kong] looked at me as if I had two heads," [Peter] Lu told New Scientist.

The evidence is circumstantial, but still very interesting.