We analyze development trajectories of early civilizations where population size and technology are endogenous, and derive conditions under which such societies optimally “switch” from anarchy to hierarchy – when it is optimal to elect and support a ruler. The ruler provides an efficient...

The World Health Organization (WHO) recommends exclusive breastfeeding (EBF) for six months, yet this recommendation has proven difficult to implement. Here, we examine the nature of and influences on early supplementation (ES) in light of current evidence regarding evolved human caregiving...