Abstract: I review network aspects of human dynamics that link macro-historical to microsociological and evolutionary processes. The ability to bond in communities of varying spatial scales is a special property of humans that happens through social networks. These networks have greater cohesion through invulnerability to disconnection without removal of k nodes. Menger’s (1927) connectivity theorem shows that this property of k-cohesion mutually entails k node-independent paths between every pair of group members. Because of this property, i.e., by redundancy of communication, humans in such communities can utilize language and long-range communication to compensate for diminishing face-to-face interaction as groups grow large. For a given level k of cohesion, the maximally extensive e(k) group size is unbounded and scalable because, for each cohesive intensity level k, the maximal group size e(k) can expand indefinitely without the need to increase the average number of ties per member. Hence, the growth of human community size is scalable at a fixed cost in number of ties per person, unlike those species unable to take advantage of k-connectivity. Strong causal effects, using the k cohesion-level measure of empirical groups whose boundaries and extent are defined by e(k), have been replicated and validated in various sociological and anthropological network studies. This allows me to examine the micro-macro linkages between