Linked: How Everything Is Connected to Everything Else and What It Means for Business, Science, and Everyday Life

A number of long-range random links, if combined with densely knit clumps, produce a low degree of separation of each person from everyone else on the planet. This patterning of networks and the low level of separation of people worldwide is one reason why future diseases, rumours, information and innovations can spread rapidly (Watts 1999, 2003).

The pattern of many connections within one tight community, punctuated by occasional ties to distant communities, describes a vast range of systems. Neurons in the brain mostly connect within one cluster, but occasionally their axons extend far outside, to an entirely different cluster. Proteins in a cell mostly interact within one functional group

These data make a strong case that, as human social networks grow, they necessarily lead to systems that require fewer resources per person, and produce more per person. In other words, the benefits of scale for human groups have always been there.