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.

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.

It used to be thought that our genes were historically immutable and that it was not possible to imagine a conversation between culture and genetics.

We cannot understand our humanity just by studying individuals.

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 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 fashionable to speak about vulnerable populations in medicine and public policy, but it's harder to find a more vulnerable population than those who are dying.

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.

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.

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.

What constrains or enables the capacity of human beings to work in groups is not so much the technology, but rather the capacity of the human brain to have and monitor social interactions.

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

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.