http://en.wikipedia.org/wiki/Evolutionary_developmental_biology#The_developmental-genetic_toolkit http://en.wikipedia.org/wiki/Evolutionary_developmental_biol..

http://en.wikipedia.org/wiki/Evolutionary_developmental_biology#The_developmental-genetic_toolkit http://en.wikipedia.org/wiki/Evolutionary_developmental_biol... Biological systems are highly coupled but also very "fault" tolerant if manipulated at the right pivot points. That's why you can move a fly leg from the torso to the head by just manipulating a few transcription factors.