Reputation is one of humanity's great concerns. If novels, poems, and drama are any guide, perhaps only love is more important to us.
But while it's easy to see the point of love, not least as a means of answering our biological imperatives, reputation is more mysterious. Why should we care so much about what other people are thinking about us? Why do people kill themselves out of shame, or kill others to preserve their honor?
The answer is both kind of obvious, and complex and profound. We care because we can't get by without each other's help. The key to our success, as individuals, societies, and a species, is the ability to work together on projects such as hunting, agriculture, warfare and industry.
Humans, in other words, are great cooperators. Cooperation is life's most potent commodity - think of how social insects, such as ants and termites, dominate their environments. And it's one of the rarest, because cooperators are always vulnerable to cheats, who take the benefits of social life without paying their dues.
A social immune system
If cheats prosper, cooperation collapses. So, just as a body needs an immune system to protect it from invaders, a society needs protection, and people need a way to channel their altruism to where it will yield a worthwhile return.
One way to do that is through direct experience - if someone is nice or nasty to you, you can reciprocate the next time you meet him or her. But imagine if you had to make all your decisions this way. If you wanted to know whether somewhere was a nice vacation destination, you'd have to go there. If you wanted to know whether a dentist was any good, you'd have to open wide. If you wanted to know whether a potential date was the one, you'd have to date them for long enough to work that out.
Life would be inefficient. It would also be vulnerable, because there would be no way to detect incompetence or dishonesty in advance. Wouldn't it be great if there were a labour-saving device to help us make decisions without having to suck it and see?
Reputation is that device. It's indirect experience that allows us to learn from how other people have fared. This leads to people taking their vacations in, say, Hawaii rather than Tulsa, but more importantly, it provides a social immune system that helps keep the good guys in and ostracize the villains.
But, of course, knowing other people's reputations is only half of it. This is a game where we have to play every position on the field. The knowledge that how others will treat you in the future depends on how you treat the person in front of you at present is a colossal incentive to good behaviour. Take that incentive away, and most of us become less decent.
Reputation, in other words, is a means for us to control one another. Your reputation lives in the minds of those who know you, and know about you, where it is both an ambassador who will advance your own interests, and a hostage at the mercy of your own bad decisions or another's malice.
The eyes have it
Evidence for how deeply embedded this is in our biology comes from the thriving micro-discipline within psychology of experiments looking at how pictures of eyes affect behavior. In the lab and the field, the scrutiny of even obviously fake stimuli - such as a banner image, a robot (pdf), a line drawing (pdf), or just some dots (pdf) - makes people more willing to share, and more likely to do their bit.

Anything that makes us feel watched makes us behave better. [Credit: silverfox09/Creative Commons]
The benefits of playing to the crowd make reputation an amplifier of behavior. But that doesn't just apply to good behavior. Other experiments have found that fake scrutiny also makes people more judgemental of transgressions, and more willing to inflict punishment (pdf). When a reputation for toughness and implacability seems valuable, social factors can also make us nastier.
I've recently published a book on all this: People Will Talk: The Surprising Science of Reputation. It looks at how much of our time, energy and biology we devote to building and protecting our own reputations, even when we don't realize we're doing it. Reputation has played a part in the evolution of pretty much everything that marks our species out, such as language, big brains and self-consciousness.
I also show that how a society works, for good or ill, has a lot to do with what people know about each other, and what they want to be known for.
That the book is not 1,500 pages long will tell you that this is far from a complete look at the role of reputation in human life. Nevertheless, even my geeky angle is broad enough to take in topics from cleaner-fish behavior to climate-change policy; from celebrity gossip to honor violence; and from the function of shame to the benefits of illegal file-sharing.
In this blog, I'll be taking that forward, looking at the latest work on reputation in fields such as psychology, evolution, economics, animal behavior, and social networks. I'll also be looking at how reputation works when our ancient instincts find themselves in new environments, such as online. And I'll be taking a reputation-eye view of life in general, looking at how factors such as transparency, anonymity and accountability influence the way the world works.
The study of reputation is really cool. The power of reputation is really important. And the subject of reputation is everywhere right now, from the leading edge of evolutionary theory to business buzzwords such as reputation management. It'd be great to have you along, and it'd be great to hear your thoughts.