This contrast clearly points to an important conclusion for development
sequencing, i.e., human development seems to be a necessary prerequisite for long-term
sustainable growth. Human development may, moreover, exhibit threshold effects, in the
sense that nations must attain a certain HD level before future economic growth becomes
sustainable. This emphasis on levels differentiates human development from human
capital in endogenous growth theory. While changes in human capital and labour quality
matter most for endogenous growth, it is the level of human development that determines
a nation’s sustainable growth path.