Altruism is one of the most fundamentally social impulses, and doing things for others without expecting anything in return is core to what makes us human. This is why, from the day Facebook Platform launched in 2007, Causes has been honored to be one of the most popular applications, with over 140 million users.

People can care about changing the world. But what gets them to act is pressure and social reward.

Without social networks, you're not the coolest thing on the Christmas list, and you're not getting any bite.

As I and the rest of my Pittsburgh Steelers teammates prepared that week in late December 1974, we knew one thing: The road to the Super Bowl in the AFC went through Oakland. To achieve your dreams as a team, you had to slay the Oakland Raiders. They were the barometer of what it took to be a championship team.

Remember all of the 'me too' social networks built just to have a social feature Facebook and MySpace didn't have? I built one for political discussion called Essembly. It enabled unique and potentially transformative social interactions, but only 20,000 people ever used it.

I was quitting…As I was taking those steps I was saying, ‘Somebody please stop me.’ Lionel Taylor, our receivers coach, said, ‘Hold up a minute,’ and he sat down in the car and we talked. I don’t know what we talked about but I was glad we talked because I went back. And that’s when it started.

I was depressed. I was just depressed. I did not want to be a Pittsburgh Steeler because I knew of the record.