The reason we form networks is because the benefits of a connected life outweigh the costs. It's to our advantage as individuals and a species to assemble ourselves in this fashion.

People have just assumed that... if we call our Facebook acquaintances our friends, we must be influenced by them, too. But we're not.

It is the spread of the good things that vindicates the whole reason we live our lives in networks. If I was always violent to you or gave you germs, you would cut the ties to me and the network would disintegrate. In a deep and fundamental way, networks are connected to goodness, and goodness is required for networks to emerge and spread.

Realizing the ways in which we humans may have been inadvertently changing our genes for millennia provides a way for us to begin to think about the inevitable genetic revolution in medicine that is going to allow us to advertently change our genes over centuries and even decades.

We cannot understand our humanity just by studying individuals.

Everyday interactions we have with other people are definitely contagious, in terms of happiness.

One reason citizens, politicians and university donors sometimes lack confidence in the social sciences is that social scientists too often miss the chance to declare victory and move on to new frontiers.