The book by Nicholas A. Christakis and James H. Fowler aims at revealing the concealed impact of social networks on the life, moods, activities and attitudes of people. It offers an alternative viewpoint on the human interactions and argues that people who one does not even know influence his or her life heavily. The authors combine a huge number of social and psychological theories offering statistics, genetic research and sociological surveys to prove their opinion and show how an individual is affected by people surrounding him or her. More than that, the authors give a workable way for every person to consciously realize the whole scope of positive and negative influences that he experiences and to model his or her life according to the way they desire. One of the authors, Nicholas Christakis, introduces a term “dyads” stating that all people in the world are interconnected and investigating the nature of these connections. Thus, the author summarizes the key to research in the nature of varied connections that can be observed in daily practices of all individuals without exception:

“If a wife falls ill or dies, her husband’s risk of death assuredly rises. Eventually, I began to realize that there were all kinds of dyads I might study, such as pairs of siblings or pairs of friends or pairs of neighbors who are connected ( not separated) by a backyard fence” (Christakis and Fowler, 2009, ix).

The first chapter represents the basic information about the inner construction of a social network and its types. The term of a dyad is explained, and the place of an individual in the network is analyzed (whether people are in the center of a group or at the periphery etc.). The authors also discuss three types of groups: a bucket brigade, a telephone tree and a military squad, and their distinguishing peculiarities, the direction of ties within them and the place of each member thereof. In this chapter they introduce the notion of the group as “a collection of individuals defined by a common attribute” and find out why the group connections are spreads only on a three-degree scheme and not more (Christakis and Fowler, 2009). In their judgment they rely more heavily on the assumptions of information corruption, the network instability and the evolutionary predisposition of people to pass on social influences on three degrees only (Christakis and Fowler, 2009).

The second chapter is dedicated to the issues of emotions and their transmission from one individual to another one. The authors argue that one can be influenced by the emotions of a person who they do not even know, thus proving the three-degree scheme. They prove their point by recollecting the Tanzania experience with mass hysteria: “In 1962 in Tanzania an epidemic of laughing spread through many villages resulting in the closing of several schools” (Christakis and Fowler, 2009). This happened because of only three girls, with the epidemic quickly spreading to vast areas and affecting a huge number of people. The same practices can be seen in the negative form – when a friend speaks about severe pain he feels, one can also feel pain or sickness after that talk. Christakis and Fowler (2009) state that emotions govern group activity shaping behavior and enhancing the human bonds. Special attention in the chapter is paid to the ability of imitate the mimics of others. Many causes of diseases are found in the unconscious imitation, and many tendencies in family influences are found out (the way family members influence each other). Which is also important, the authors find the direct connection between loneliness and social ties – “Happy and unhappy people cluster among themselves”, “Each unhappy friend deceases the likelihood of happiness 7%” etc. (Christakis and Fowler, 2009). These examples clearly prove how susceptible of others’ behavior and emotions all people are and how they can influence their own life by changing the social network in which they operate.

The third chapter is dedicated to the issue of love and its social origin in everyone’s life. First of all, the authors distinguish such types of love as lust, love and devotion and state that they have different objects and different nature (Christakis and Fowler, 2009). Arguing the social origin of love, the authors give examples of surveys revealing how the couple formed: “68% of people were introduced to their spouse by a common acquaintance” (Christakis and Fowler, 2009). Further on the chapter is dedicated to finding the key to matchmaking and married life that is proven to be governed by homogamy (the wish to marry with someone alike). The concepts of relative standing and absolute standing are discussed, with the conclusion made that people are obsessed by the former, which influences the perception of sexual appeal and self-esteem. The authors favor marriages and state that “When men get married there is a sharp and dramatic decline in their risk of death” (Christakis and Fowler, 2009).