Optimal levels of cooperation are achieved at intermediate levels of change in social ties.

Interesting, if early, research. From Quality versus quantity of social ties in experimental cooperative networks by Hirokazu Shirado, Feng Fu, James H. Fowler & Nicholas A. Christakis.

Goes to an issue I have assumed to be true for a long time.

In complex systems, introducing increasing levels of change puts the system under stress and risks dissolution. Too little diversity in the system and it becomes fragile and unadaptive. There is a sweet spot between too much and too little.

Similarly, I have hypothesized, in terms of immigration, that there is a sweet spot in the middle. Too little immigration (and therefore variety/diversity) and the existing system becomes staid and sclerotic. Too much immigration and it overwhelms traditional societally adaptive mechanisms. My guess is that, at least for the US, the range is somewhere bounded by 5 and 15% foreign born.

From the Abstract.

Recent studies suggest that allowing individuals to choose their partners can help to maintain cooperation in human social networks; this behaviour can supplement behavioural reciprocity, whereby humans are influenced to cooperate by peer pressure. However, it is unknown how the rate of forming and breaking social ties affects our capacity to cooperate. Here we use a series of online experiments involving 1,529 unique participants embedded in 90 experimental networks, to show that there is a ‘Goldilocks’ effect of network dynamism on cooperation. When the rate of change in social ties is too low, subjects choose to have many ties, even if they attach to defectors. When the rate is too high, cooperators cannot detach from defectors as much as defectors re-attach and, hence, subjects resort to behavioural reciprocity and switch their behaviour to defection. Optimal levels of cooperation are achieved at intermediate levels of change in social ties.

Indeed.

The Greeks and their golden mean.