And yet most of humanity's scientific and technological progress happened in a part of the world (Western Europe from about 1500 to 1900) with relatively weak kinship networks by world-historical standards.
While they could have been relatively weak, I would not presume they were weak or played a small role in progressing civilization. Being a cousin was recognized as being important for lots of things at the leadership levels and I assume that filtered down to society:
> Traditionally, many factors were important in arranging royal marriages. One such factor was the amount of territory that the other royal family governed or controlled.[4] Another, related factor was the stability of the control exerted over that territory: when there was territorial instability in a royal family, other royalty would be less inclined to marry into that family.[4] Another factor was political alliance: marriage was an important way to bind together royal families and their countries during peace and war and could justify many important political decisions.[4][116]
I’m just pointing out that friendship networks are a treated differently than kinship networks because they are. Hard to deny the economic effectiveness of the western model, however.
