If your friends are obese, your risk of obesity is 45 percent higher. ... If your friend's friends are obese, your risk of obesity is 25 percent higher. ... If your friend's friend's friend, someone you probably don't even know, is obese, your risk of obesity is 10 percent higher. It's only when you get to your friend's friend's friend's friends that there's no longer a relationship between that person's body size and your own body size.

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.

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.

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

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.

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

We cannot understand our humanity just by studying individuals.