I imagine the earth like this. We are all living on the surface of the earth, and at the same time, we are on the tip of a human tree. Some branches of this tree are called "ethnic groups," some are called "genders," some are called "nations," some are called "religions," some are called "colors of skin," some are called "classes," some are called "levels of education," some are called "legal & illegal," and it goes on. Those branches are often referred as communities, societies, neighborhoods, clubs, groups, villages, etc. They often have a characteristics of being exclusive to non-members while the members share norms, customs, and values.
It is easier for people to communicate among the members of the same branch because they don't need to go further down. They simply move down to a splitting point where their branches meet with other members. On the other hand, it is overwhelmingly hard to go all the way down where all the branches are rooted in; it requires open-mindedness and adaptation to reach that point. The real communication , however, begins when we go all the way down to the root of the tree.
stirps mean roots- roots of people in human history. We are all related if we go back to the root of our family trees. Likewise, we can feel that we are all related as we go down to the root of out humanness. stirps network builds human network toward its root.