I include this for three good reasons:
- Because it supports the idea that we as humans have an innate, hard-wired understanding of music. 
- Because it’s possibly my favourite YouTube video of all time. 
- Because Bobby McFerrin is made of pure music. 
(If you’re curious about the hand image, it’s not specifically related to the pentatonic scale, other than having five nodes and being a tool for learning scales. It was invented in the 10th century and is known as a Guidonian Hand. This is a modern one made by music educator, Odd Quartet, who also has a good video explaining how it works and how it was used. It’s a fascinating thing. If you like that sort of thing. Which I do.)
