  Social structure affects the emergence and maintenance of cooperation. Here
we study the evolutionary dynamics of cooperation in fragmented societies, and
show that conjoining segregated cooperation-inhibiting groups, if done
properly, rescues the fate of collective cooperation. We highlight the
essential role of inter-group ties, that sew the patches of the social network
together and facilitate cooperation. We point out several examples of this
phenomenon in actual settings. We explore random and non-random graphs, as well
as empirical networks. In many cases we find a marked reduction of the critical
benefit-to-cost ratio needed for sustaining cooperation. Our finding gives hope
that the increasing worldwide connectivity, if managed properly, can promote
global cooperation.
