What stunts economic growth and causes the poverty trap?

In spite of an identical initial condition, why are some parts of the world so rich and others so poor? To address this question, this paper constructs a simple theoretical model that incorporates human infrastructure and child labor The first part of the paper shows that the condition of bifurcation from an identical initial condition depends on the technology level. We also show that current dynamic trends highly depend on initial endowments and productivity. The second part of the paper examines the effect of development assistance in recipient countries. By analyzing two types of programs; the elimination of child labor and support to strengthen human infrastructure, we show that the former (latter) program is effective for middle- (low-) income countries