Long ago, as the design of the Unix file system was being worked out, the entries . and .. appeared, to make navigation easier. I’m not sure but I believe .. went in during the Version 2 rewrite, when the file system became hierarchical (it had a very different structure early on).Rob Pike — https://plus.google.com/u/0/+RobPikeTheHuman/posts/R58WgWwN9jp
Emphasis added. Intriguing!