#### Introduction

The bebop revolution rejuvenated (among other things) the blues. But the old fashioned blues didn't fit in with bebop's complex harmonies, melodies and rhythms. The twelve bar blues was, (and still is), the most popular form of blues, but the harmonies are extremely simple (read about it here), as are the melodies, which are mostly pentatonic. Likewise, improvising the twelve bar blues is mostly pentatonic, although it is possible to improvise over the changes, using more 'advanced' scales. Even so, it does not allow for the complexity of bebop. So the bebop musicians took the basic blues form and changed it a 'little'. The harmonies were changed, a little at first, and then almost beyond recognition, as were the melodies.

#### Harmonic Evolution

I'll illustrate the changes made to the twelve bar blues, hopefully explaining step by step how 'monsters' like "Blues For Alice" emerged.

I will write every progression in the Roman Numeral system (IIm7 means 2nd degree minor seventh, so for example in the key of C, I7 would be C7, IIm7 would be Dm7 and bVImaj7 would be Abmajor7). I will also write an example for each. All the examples will be in F. (I will quickly lose the roman numerals, for reasons to follow).

A basic twelve bar blues looks like this:

```     I7 | IV7 | I7 | I7 | IV7 | IV7 | I7 | I7 | V7 | IV7 | I7 | V7 ||
F7 | Bb7 | F7 | F7 | Bb7 | Bb7 | F7 | F7 | C7 | Bb7 | F7 | C7 ||
```
Let's change it a little:
```     I7 | IV7 | I7 | I7 | IV7 | IV7 | I7 | VI7 | IIm7 | V7 | I7 | V7 ||
F7 | Bb7 | F7 | F7 | Bb7 | Bb7 | F7 | D7  | Gm7  | C7 | F7 | C7 ||
```
And we get the most basic bebop blues progression. Incidentally, I could have changed it one chord at a time, in order to explain it more fully, but I'm counting on your intelligence to be able to figure it out. I'm assuming at least a little knowledge of music theory. If you don't know any music theory, you'll find it very hard to play bebop anyway. If you have any questions, though, message me.

So what have we actually done? We've taken the V7 | IV7 | I7 cadence in bars 9-11, and made it into a V7 | V7 | I7 cadence, which is fine. (In blues the IV7 is added mostly for interest.) Then we expanded it, adding the relative II. So we have a II-V-I turnaround, which is extremely common in bebop, and in jazz in general. Remember, wherever you have a dominant 7th chord, you can turn it into a II-V progression, by adding it's relative II.

Then we added D7, which is the secondary dominant of Gm7. So where I've writen VI7, it's actually a V7/IIm7, though nobody refers to it as that.

When you're playing in a band, or in a jam session, and somebody says, "Let's play bebop blues", this is the progression they're usually referring to. If you play it, you can't go wrong.

Let's spice things up. Where we have a dominant 7, we can turn it into a IIm7-V7. Let's do it, and let's abandon the roman numerals, because it's going to be a real pain in the ass to try to explain it using them. Also, let's make some more advanced changes: (And I will write it out in 2 lines, so all themes and all browsers will be able to view this).

```   | F7  | Bb7 | F7  | Cm7 F7 | Bb7 | Bb7    |
| Am7 | D7  | Gm7 | C7     | F7  | Gm7 C7 ||
```
In the 4th bar, we have turned the dominant chord into a II-V. This works, as it helps establish the Bb7 chord. In bar 4, the F7 could be seen as a pivot chord, being the I7 or the V7 or Bb7. This is why I abandoned the roman numerals. It would just look complicated. What you DO have to know is that there is now a II-V progression to Bb7. In bar 12 we have done the same thing. In bar 7, we changed the F7 to Am7. We can do this for two reasons: 1) Am7 is the third degree of the F scale, so it's interchangeable as a tonic. But we'll ignore that, even though it's true. The real reason we do this is because Am7 is the relative minor of D7, so we have a II - V to Gm7.

```   | F7    | Bb7   | F7  | Cm7 F7 | Bb7 | Bdim   |
| Am7b5 | D7b13 | Gm7 | C7     | F7  | Gm7 C7 ||
```
II-V to Gm7? Well, why not make it a proper II-V to a minor chord? That's right, a II-V progression to a minor chord is IIm7b5-V7, so we changed to Am7 to an Am7b5. I've also written D7 as D7b13. This stresses the fact that it's a dominant 7th chord leading to a minor chord (as it now has a Bb). It can also be written as D7b9b13 if that's the sound you're looking for. (If you (or the composer) specifically want a mixoldian b13 sound, write it as D7b13. If you specifically want a mixolydian b9b13 sound, write it as D7b9b13). Usually, you won't see D7b13, but just D7. I wrote this variation here so that you'll be aware of this possibility. In any case, the D7 should be treated as the fifth of a minor chord.

If you look carefully, you'll see that between Bb7 (Bb-D-F-Ab) and Bdim (B-D-F-Ab) there is a difference of one note. In this case, they are easily interchangeable. In fact, this is a common substitution, and I probably should have put it in the first example, because it is used so much. However, it is a more advanced substitution, so I left it to now. Moving on:

```   | F7    | Gm7 C7 | F7  | Cm7 F7 | Bb7    | Bdim   |
| Am7b5 | D7     | Gm7 | C7     | F7 Dm7 | Gm7 C7 ||
```
We replace the 2nd bar's Bb7 by a II-V to F7. This changes the sound a bit drastically, so don't do it unless the song specifies it. Also, we changed the last 2 bars to a I-VI-II-V progression. The I-VI-II-V progression here is the simplest one, using chords derived from the F major scale. Common variations can be found here.

One more thing: let's throw in a sub V or two:

```   | F7  | Gm7 C7 | F7  | Cm7 F7 | Bb7    | Bdim   |
| Am7 | Ab7    | Gm7 | F7     | Eb7 D7 | Db7 C7 ||
```
I've changed the D7 in bar 8 to Ab7, its sub V. Then I've taken the | Am7 D7 | Gm7 C7 | at the end, turned it to a | A7 D7 | G7 C7 | (why? because I can), and shoved in some sub V's too.

Before I go into the freaky stuff, I'll write a common bebop blues progression, using stuff we learnt. Note that you can add or remove stuff at will, and you can play any combination of what we did when the soloist is playing. They will all sound good. Also, you can improvise over whatever progression you like, 'ignoring' what the rhythm section is playing, because you really can't do much wrong. If you play Bdim over a Bb7 chord, you're just using a diminished scale over a dominant chord, which has a lovely texture. If you play II-V over a V, well, you should be doing that all the time anyway :) etc.

```    | F7 | Bb7 | Cm7 | F7 | Bb7   | Bdim  |
| F7 | D7  | Gm7 | C7 | A7 D7 | G7 C7 ||
```
On to the crazy stuff:
```   | Fmaj7 | Dm7 G7 | Cm7 | F7 | Bb7   | Bdim   |
| Am7   | D7     | Gm7 | C7 | F7 D7 | Gm7 C7 ||
```
Say it: "Footprints, what the hell are you doing?" And then I reply: "Who said the first chord has to be a dominant 7th?" Yes, it's radical, but then again, so is bebop. About the Dm7-G7, you're probably figured it out - a II-V to Cm7. Now let's go crazy:
```   | Fmaj7  | Em7b5 A7 | Dm7 G7 | Cm7 F7 | Bb7    | Bbm7 Eb7 |
| Am7 D7 | Abm7 Db7 | Gm7    | C7     | F  Dm7 | Gm7  C7  ||
```
What??!! Well, this is Blues For Alice, which is, indeed a blues. Let's take it slowly. We start off with Fmaj7. We want to get to Bb in the 5th bar. So we'll put a II-V before that. Then let's stick in a II-V to Cm7 before that. And, oh what the hell, as we're already putting II-V's everywhere, let's just stick a II-V before the Dm7. So thus we get to Bb7. (This is not a very strict harmonic dissection of the progression, but it's good enough for us.) Then it get a bit hard to explain, but the chromatic descent is very common (and stems mainly form sub V's). The chromatic II-V's lead us to Gm7, where we find the 'normal' bebop blues ending.

Whew!

#### Melodic Evolution

Actually, the melodic evolution stemmed mostly from the harmonic one. Changes such as the II-V had to be accounted for, and this was reflected in the melodies. But yet another melodic change, which stems from another part of the bebop revolution, is the extensive use of chromaticism by some composers. The most dominant and famous, of course, being Thelonious Monk. Take a look at Blue Monk or Straight No Chaser for examples of the use of chromaticism. The entire head is based on the use of chromatic notes.

Not only were there new chords, but there were also scales. By new I mean that they hadn't been used in the blues context before. Scales like the altered scale, for example, had not been in use much before bebop, and it found it's way into blues melodies.

In improvisation, new harmonic thought crept in, thus allowing for melodies nobody had ever thought possible. Take Charlie Parker's solo over Blues (fast). In the 8th bar, he plays a Dbm7 arpeggio, over a Bb7 chord. What? Look carefully, and notice that in the bar before, he played a Dm7 arpeggio, and he's leading to a Cm7, so in fact, he's playing over | Dm7 A7 | Dbm7 Gb7 | Cm7 |, which makes perfect sense. He 'leads' the harmony with his melody.

#### Improvising

Well, this is a bit complicated to explain in just one writeup, but I think you've picked up alot just from the notes above. You can, in fact, just use the blues scale, as you would over a normal twelve bar blues. It's nice to throw in a bit of the blues scale when improvising over bebop blues, but not too much, because it sounds poor (as in the opposite of rich). It sound poor to use only the blues scale with all this hamonic texture behind you.

Basically, you should practice playing the 'correct' scales over each chord. So over F7, play the F7 mixolydian. Over Bb7, play Bb7 mixolydian, etc. It's important to try to make the II-V come out (as a II-V sound, and not just play 'correct notes'). so over | Gm7 C7 | F7 | don't play the Fmajor scale over the II-V, but play something that will lead better to the F. That's what the II-V is there for. For example, a G-Bb-D-F-E-C-Bb-G-|A (all 8th notes) would work. Work on your II-V progressions.

Over the D7 in bar 8, use a D mixolydian b13, D mixolydian b9 b13, D altered, or some similar scale. You want to emphasise that it's a dominant leading to Gm7.

Over Bdim, the preferred scale is the whole tone-half tone diminshed scale. Over the turnaround, play what you usually play over a bebop turnaround. (Play over any variation of the I-V-II-V. Even just playing as if it is a II -V will work fine.)

Feel free to use the bebop scales, and use intersting tensions and chromatic approaches.

Oh, and have fun!