Turn on the sound and click the play button on the video below, this is cool:
If you are interested in the details of the Pentatonic Scale follow this link . The fact that this type of scale is used in a wide variety of cultures may explain the natural, intuitive way the audience reacted in the video. Here is a post about McFerrin's technique for "teaching" the scale to the audience - don't be put off by the name of the site. And the World Science Festival site can be found here .
Enough of the intellectualizing already! McFerrin is most famous for Don't Worry Be Happy which you can see at this link (embedding is disabled, unfortunately) but clearly there is much more to him than just that great song.
Here he is singing Ave Maria at a Jazz Concert.
If you want some more, here is a link to his YouTube channel.