Sometimes our emotions guide us to act in ways that are, in some formal sense, irrational. But in a practical sense, are actually beneficial. And one illustration of this is gained from behavioral economics called the Ultimatum Game. And here's how the Ultimatum Game works. You have two characters, A and B. And A is given, say, $10 and is asked how much of this $10 do you want to give to B? Everything from a dollar to all of it. And the rule is that B now has an option. B can either accept the money, so now A keeps whatever money A didn't give away and B keeps whatever money he or she got or rejects it. And if B rejects it, nobody gets anything. Now, imagine if the people are perfectly rational. If people are perfectly rational, then the offer A should offer the minimum $1. And B should accept it, because $1 is better than nothing. If you say, I reject it, nobody gets anything. And remember, this is a one shot game. You're just playing this once, so you can't really punish people so that they behave better in the future. But interestingly, even for a one shot game, people don't do this. They often don't accept unfair distributions, they reject them out of spite. So, I know if I'm dealing with such a person, if I offer him or her $1, or $2, $3, they'd say, no way, and now, nobody gets anything. But because of this, because of their irrationality, they get more money from me than a rational person would get. If I'm dealing with a rational person, I just give a small amount of money. Dealing with an irrational person, I have to deal with more. And in general, there's a social usefulness of irrationality, of being emotional. A rational person is easily exploited, because their response to provocations and to assault is always going to measured inappropriate. If I go up to somebody and I steal a dollar from him, a perfectly rational person will say, I'm not going to make a big deal out of it, it's only a dollar. A person with a temper will have an advantage, a person with a temper might say you stole my dollar, I'm going to kill you. I'm going to kill your whole family and that's crazy. But when you deal with a crazy person, the person has the advantage that you're less likely to want to provoke them. Now there are matters of degrees here, it gets complicated. If a person is too prone to respond to provocation, then you won't deal with them at all. So there's a certain optimal level of irrationality. If a person would only accept a distribution if you gave them $7 then you know, they're a rotten person to deal with and then you'll both end up worse in the end. But these sort of considerations leave you to realize that responding perfectly rational to a situation is a disadvantage, sometimes. Particularly, in a case where there's the possibility of violence and assault. A reputation for erratic and extreme response can make you better off. Now, it often pays to be irrational, but it can have tragic results. What's adaptive for individuals and what makes sense from an evolutionary point of view may be very bad for people in general. In their wonderful book on murder, on homicide, Daily and Wilson point out that a major cause of murder is actually offenses to people's honor, insults, curses, petty infractions. And they write, in chronically feuding and warring societies, an essential manly virtue is the capacity for violence. To turn the other cheek is not saintly but stupid. Or contemptibly week. Now what we see here, it's an idea I am introducing at the very end. Is that there are cross-cultural differences in the extent to which certain emotions and certain sentiments are expressed. And interestingly here, the importance of reputation and importance to reputation for a capacity for violent reprisal varies from culture to culture. Sociologists describe a culture of honor and a culture of honor is one where you can't rely on the law. And you have resources that are easily taken, like herders. And in such a culture, a capacity for excessive violence is essential to keep your resources. And we see these cultures of honors around the world. There are Scottish Highlanders, Masai warriors, Bedouin tribesmen, Western cowboys,. One case in the United States, an area where there's more of a culture of honor is the American South. It was settled by Scottish and Irish herdsmen, and they have less centralized legal control. You don't need a reputation for violence if there's a cop around every corner, if attacks on you can be addressed properly and quickly by the state. You need it when there's no police to help you. And what's interesting is that we can see the culture of honor manifest itself in all sorts of psychological differences. Between individuals within such a culture and outside such a culture. So if in the United States, for instance, you find people who are raised within cultures of honor have more permissive gun laws. They're more accepting of capital and corporal punishment. They have better attitudes towards the military. They're more forgiving towards crimes of honor, like killing someone in a fight because they insulted somebody you love. And they have higher rates of violence but only for crimes associated with honor. They don't have higher rates of violence because they have more violent gang wars or more violent bank robberies. But rather bar fights, things that are triggered by insults to one's honor. And a very cool study, which I'll end with, explored this by Nisbett and Wilson. They did this at University of Michigan, and they tested undergraduates. And they were from a narrow group, they were all white males, not Hispanic, not Jewish. Some of them came from the South, and some of them came from the North. And they didn't know what the experiment that they were doing was about. But what happened was, they get to go to a room, and they fill out some papers and did some tasks. And then they were told to walk across the hall. As they were walking across the hall, a graduate student walked by and bumped them with his shoulder, nudged them aside, and then said a very rude word to them. Now, afterwards, they were tested. And it turned out that the people from the South were far more upset, energized by this interaction than the people of the North. They had greater levels of testosterone, cortisol, stress hormones. They gave a stronger handshake. They gave more violent words when asked to fill in the blank and this suggests that their psychologies are different. That in some subtle way being raised in one culture makes you, among other things, more aggressive when insulted then in another culture. Emotions, although having evolutionary roots, can be calibrated by culture. And more generally, I hope that the studies we talked about and the evolutionary approach that we took. Suggests that emotions like fear and the love we have towards our kin, anger, gratitude and so on aren't noise in the system. They aren't aberrations we should get rid of. We wouldn't be better off without them. Rather, they're complex motivational systems evolved to solve problems, sensitive to the culture. Exquisitely crafted to deal with these natural and social environments that we live in.