• Our ancestors got smart primarily to compete against each other in a variety of social and political scenarios.
• Social challenges, such as competition for mates, jockeying for social status, coalition politics (alliances, betrayals, etc.), intra-group violence, cheating, and deception, pit humans against other humans and are therefore competitive and potentially destructive.

• For sociologists and anthropologists, conventions like queueing are known as norms. They're the rules or standards about how members of a community should behave.
• Collective enforcement, then, is the essence of norms. This is what enables the egalitarian political order so characteristic of the forager lifestyle.

• Norm-evaders and norm-enforcers are locked in a competitive arms race of their own-a game of cat and mouse-pushing each other ever upward in mental ability.
• Our norms are only partially enforced, so we need big brains to figure out how to cheat.

• The perverse incentives of mixed-motive games lead to option-limiting and other actions that seem irrational, but are actually strategic
• Closing or degrading a channel of communication
• Ignoring information, also known as strategic ignorance
• Purposely believing something that’s false
• A general who firmly believes his army can win, even though the odds are against it, might nevertheless intimidate your opponent into backing down
• Convince others that you’ve sabotaged yourself.

When we use the term "motives," we're referring to the underlying causes of our behavior, whether we're conscious of them or not.

Reasons can be true, false, or somewhere in between (e.g., cherry-picked). One of the most effective ways to rationalize is by telling half-truths.

• Human beings are strategically blind to body language because it often betrays our ugly, selfish, competitive motives
• A cue is similar to a signal, in that it conveys information, except that it benefits only the receiver
• An open posture makes a person vulnerable
• Much of the thrill and drama of courtship lies in struggling to decipher the other's mixed signals
• When we feel comfortable around others, we touch them and allow ourselves to be touched
• Eye contact is considered an act of aggression.

• We laugh far more often in social settings than when we are alone
• It's a vocalization, a sound, and it serves the purpose of active communication
• When we laugh at our own actions, it's a signal to our playmates that our intentions are ultimately playful
• In other species, laughter occurs even in other species
• The danger of laughter is the fact that we don't all share the same norms to the same degree
• What's sacred to one person can be an object of mere play to another.

Speakers strive to impress their audience by consistently delivering impressive remarks.

They're compensated not in-kind, by receiving information reciprocally, but rather by raising their social value in the eyes (and ears) of their listeners.

• We are stuck in a rat race
• No matter how fast the economy grows, there remains a limited supply of sex and social status-and earning and spending money is still a good way to compete for it
• The easier it is to judge someone based on a particular product, the more it will be advertised using cultural images and lifestyle associations.

• While ecological selection (the pressure to survive) abhors waste, sexual selection often favors it
• Because replicas are cheap relative to the originals, we'll pay less to see a much wider variety
• We find attractive things that could have been produced only by people with attractive, high-fitness qualities
• A live performance, or an improvised one, succeeds by putting the artists' talents on full display.

• According to one calculation, for the cost of sending a kid through college in America, you could instead save the lives of more than 50 children in sub-Saharan Africa
• The main recipients of American charity are religious groups and educational institutions
• When we evaluate charity-related behaviors, gross inefficiencies don't seem to bother us
• For example, wealthy people often perform unskilled volunteer work, even when their time is worth vastly more on the open market.

• If a small amount of useful learning takes place, then sending every citizen to school will result in only a small increase in the nation's overall productivity
• Meanwhile, when you're an individual student within a nation, getting more school can substantially increase your future earnings
• The top U.S. colleges draw their mystique from zero-sum competition.

• Each party is hoping to earn a bit of loyalty from the patient in exchange for helping to provide care.
• In part, it's a simple quid pro quo: "I'll help you this time if you'll help me when the tables are turned."
• When choosing between doctors, people typically focus on the prestige of their school or hospital, instead of their individual track records for patient outcomes.

• Beliefs are often better modeled as symptoms of underlying incentives, which are frequently social rather than psychological
• We don't worship simply because we believe, we worship (and believe) because it helps us as social creatures
• A religion is an entire social system
• Actions speak louder than words
• Rituals of sacrifice are honest signals that are hard to fake
• People who believe they risk punishment for disobeying God are more likely to behave well.

• People do not vote for their material self-interest
• Instead, they vote for the candidates and policies that would make them personally better off
• We tend to vote for our groups' interests
• For our beliefs to function as loyalty signals, we have to believe things that are beyond reason, things that other, less-loyal people wouldn't believe.

• We ignore the elephant because doing so is strategic.
• Self-deception allows us to act selfishly without having to appear quite so selfish in front of others.
• Another benefit to confronting our hidden motives is that, if we choose, we can take steps to mitigate or counteract them.
• One promising approach to institutional reform is to acknowledge people's need to show off, but to divert their efforts away from wasteful activities and toward those with bigger benefits and positive externalities.