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.

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.

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. That's clearly not the case when it comes to social systems.

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.

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

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

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.