It’s alchemy: A group of people is greater than the sum of its parts. A hunting party keeps the tribe fed. A bucket brigade douses the barn fire. Thirteen colonies become mightier when they unite. An assembly line mass produces autos. A tech firm creates dazzling innovation. A Twitter community brings a despot down.

What’s the magic?

The connections, according to Nicholas Christakis and James Fowler, authors of Connected: The Surprising Power of Our Social Networks and How They Shape Our Lives.  Study the ties between individuals and between networks, and you learn what makes them tick and how you might influence the individuals within.

The authors say social media technology renders the makeup and transactions within networks more transparent. This is good news if you’re working for a better world. Intractable problems such as obesity, poverty and social injustice may be better understood and addressed from a network connection framework, rather than a “fix the individual” framework.

The authors posit a Three Degrees of Separation Rule:

“Everything we do or say tends to ripple through our network, having an impact on our friends (one degree), our friends’ friends (two degrees), and even our friends’ friends’ friends (three degrees). Our influence gradually dissipates and ceases to have a noticeable effect on people beyond the social frontier that lies at three degrees of separation.”

Among the interesting implications:  It may be more effective to influence individuals through their connections two or three degrees removed. Smoking cessation efforts could be targeted at people centrally located in a network, whether or not they smoke. They are more influential on the individual smoker than his/her doctor.

Where you do not have a good picture of the network, you may be more effective randomly targeting people within a network. For example, rather than immunize the weaker people in a network (who may be on the fringes and have less influence), you might ask random people in the network to name acquaintances, then immunize the acquaintances. The people who were identified are likely to be the better connected individuals in the group who would be the most susceptible and most likely to spread contagion.

One study proved that weight loss was 33 percent greater and also more durable when people were part of a group. The Connected construct further suggests an unusual strategy: bind friends of friends in a weight loss effort, rather than the more typical cluster of friends losing weight together.  Not only would the network of second-degree connections spread the weight loss “contagion” more broadly, it would encourage long-term success because the participants will not be a small cluster of friends surrounded by a network of large people.

The authors see a direct linkage between the ancestral campfire and Facebook. Even before social media, behaviorists had determined the average individual had about four close connections and a list of 150 people whom they counted as friends (the so-called Dunbar’s Number). Interestingly, the typical Facebook user has six or seven close connections and 110 people on their “friends” list. In non-technical life, networks have three key roles: cooperators, free-riders and punishers – people who contribute to the “work” of the group, others who benefit from it and another set who keep the rules. The same roles are found in the Wikipedia ecosystem: people who post content, those who consume it and the committed band of editors who question statements and erase vandalism.

“We do not cooperate with one another because a state or a central authority forces us to. Instead, our ability to get along emerges spontaneously from the decentralized actions of people who form groups with connected fates and a common purpose. “