If one adopts the formation of a Human socialized (Homo socialis) to be one of the human cognitive evolution vectors, then an intermediary, a negotiator, or a broker can be considered as its embodiment in the contemporary society. The role of the mediator in the implementation of social interactions can be clearly described by using network analogies, i.e. the society can be represented as a social network, its nodes are associations of people (groups, cliques or clusters) linked by bridges i.e. stronger or weaker connections. Any person forms connec tions (bridges) with many various groups and this is through these bridges that information and resources are being exchanged. A group taken as a whole has fewer contacts with other groups than the individual, so there are always struc tural holes between groups. These holes become especially apparent when there is a need to establish intergroup communication. Here some particular members of the groups come into play who have connections with members of the target group, however weak those links were and who have won the trust of that target members, i.e. possess the social capital. Moreover, people occupying positions at the intersections of the weak connections of social groups get an opportunity to see, realize and use new good ideas. To achieve it, the negotiator must have high cognitive abilities that allow him/her to see opportunities in the situations where others see only structural holes. However, the structural power of the negotiators does not make them leaders of social groups, because they cannot both influence the agenda and at the same time openly pursue their own goals without compromising their status of impartial intermediaries. The revealed features of negotiators, or social brokers, are of particular interest from the point of view of their participation in social engineering techniques in order to increase the effectiveness of social interaction in economically significant projects.