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.

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 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.

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.

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.

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.

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.