The "widower effect" is referred to as "dying of a broken heart."

Nicholas Christakis' first topic with respect to social networks was obesity.

According to the math provided in the video, if your friends are obese, you are 75% more likely to be obese.

Of the reasons put forth regarding the clustering of individuals with obesity, the only reason they found evidence for was the "birds of a feather flock together" construct.

Mr. Christakis came to see social networks as living things that can be analyzed and understood.

According to the video, emotions can be thought of as a primitive form of communication.

We tend to form social networks that look like a regular lattice when mapped out.

The research presented in the video found that 46% of the variation in how many friends you have can be explained by your genes.

They also found that 47 percent in the variation in whether your friends know each other is attributable to your genes.

According to the video, we form social networks because the benefits of forming them outweigh the costs.