Sentence:  America's poverty line is $63 a day for a family of four. In the richer parts of the emerging <WSD>world</WSD> $4 a day is the poverty barrier. But poverty's scourge is fiercest below $1.25 ([...]): people below that level live lives that are poor, nasty, brutish and short. 
Meaning of the word marked with <WSD> tags:  Human collective existence; existence in general.