Why are pentatonic scales used for instrumental solos?

A Quoran asked about pentatonic scales in instrumental solos, I answered.

It is a good question.

Did you, for example, know that the pentatonic scale is a slice right out of the cycle of fifths? Just stack four fifths on top of each other and there is your major pentatonic (well, you have to put them in order first!). But that is why pentatonics are so old – the fifth is an early overtone, so many instruments can produce these five notes quite easily.
Take any five notes from the cycle of fifths and line them up one note after another and you get a pentatonic scale.

And check out more below.

Read Ariane Cap’s answer to Why are pentatonic scales used for instrumental solos? on Quora.