It is well to look around at whom, and not just what, surrounds us. Population structure will change everything. Our health, wealth, and peace depend on it.

Just because we say networks are important doesn't mean that networks explain everything. We're just adding additional information. Networks don't work like a match -- they work like a magnifying glass.

My entire youth was spent with an incredibly ill parent... I don't think you can grow up that way and not be marked by that experience.

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.

We discovered that if your friend's friend's friend gained weight, you gained weight. We discovered that if your friend's friend's friend stopped smoking, you stopped smoking. And we discovered that if your friend's friend's friend became happy, you became happy.

There are very fundamental reasons we live our lives in social networks, and if we really understood the role they're playing in our society, we would take better care of social networks and find ways to take advantage of their power to improve our society.

The social sciences offer equal promise for improving human welfare; our lives can be greatly improved through a deeper understanding of individual and collective behavior. But to realize this promise, the social sciences, like the natural sciences, need to match their institutional structures to today's intellectual challenges.

We will create life from inanimate compounds, and we will find life in space. But the life that should more immediately interest us lies between these extremes, in the middle range we all inhabit between our genes and our stars.

It's important for students to take their studies seriously.

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.

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.

Social networks are these intricate things of beauty, and they're so elaborate and so complex and so ubiquitous that one has to ask what purpose they serve.

We cannot understand our humanity just by studying individuals.

I like to have met someone in real life before being their Facebook friend.

Social media and the Internet haven't changed our capacity for social interaction any more than the Internet has changed our ability to be in love or our basic propensity to violence, because those are such fundamental human attributes.

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.

We are, first of all, not solitary creatures and second of all, we are deeply embedded in the lives of others. It's very easy to forget that and to engage in an atomistic fallacy -- where we think that all we have to do is study the individual components of a system in order to understand the system.

If we are connected to everyone else by six degrees and we can influence them up to three degrees, then one way to think about ourselves is that each of us can reach about halfway to everyone else on the planet.

Whether we appreciate it or not, we live out our lives surrounded by an intricate pattern of social connections... We're all embedded in this network; it affects us profoundly and we may be unaware of its existence, of its effect on us.

We're not just social animals in the conventional way that people think. It's not just a bunch of us who hang out together. We have a very specific pattern of ties, and they have a particular shape and structure that is encoded in our genes. It means that human beings have evolved to live their lives embedded in social networks.