Its really easy to figure out.
First their was TOS Klingons
![](http://www.boomspeed.com/chuutritt/kor.JPG)
then they encountered an "ALIEN" lifeform
![](http://www.boomspeed.com/chuutritt/Alien1.JPG)
Then unable to tolerate the notorious Klingon bad breath, the creature moved to the top of the head using its acid secretions to meld with the Klingon.
![](http://www.boomspeed.com/chuutritt/alien2.JPG)
This also explains how such a clever and sneaky race, became one of caveman simplicity and perpetual bad mood.
<SNICKER>
![Grin ;D](http://www.dynaverse.net/forum/Smileys/NewSmilies/grin.gif)