And who would adopt gang members from bad areas onto their streets?
I do have to wonder what the effect in over-crowded prisons is though. Imagine this existence: http://i.imgur.com/owvao.jpg
One criminal told Louis that he would have taken his shoes if he himself was an inmate and that he would have had to fight for them and to be allowed to stay in there. There's that phrase log cabining or wood cabining describing where you just remove yourself from society to do something creative, it's an urge we all have.
I don't find the researcher's conclusion that overcrowding results in violence and withdrawal overly surprising, but I am a little puzzled by some of the politicized reactions to his research. Why suggest that we discourage a cosmopolitan outlook and abandon welfare instead of suggesting that we improve urban planning?