String phone...

String phone...  Did you make one of these when you were a kid?  My cousin and I made one with a couple of tomato paste cans and some fly-fishing line.  He sat in the basement of his house, and I in a crab-apple tree, and we could converse quite nicely...

This is pretty low-tech stuff, and I wouldn't have been surprised to hear that these were in use in, say, the 1600s or 1700s.  But the example pictured was used 1,200 to 1,400 years ago, by the Chimú people of modern Peru.  That surprised me!