We lie to ourselves all the time. We tell ourselves that we are better than average -- that we are more moral, more capable, less likely to become sick or suffer an accident. It’s an odd phenomenon, and an especially puzzling one to those who think about our evolutionary origins. Self-deception is so pervasive that it must confer some advantage. But how could we be well served by a brain that deceives us? This is one of the topics tackled by Robert Trivers in his new book, “The Folly of Fools,” a colorful survey of deception that includes plane crashes, neuroscience and the transvestites of the animal world. He answered questions from Mind Matters editor Gareth Cook.

Cook: Do you have any favorite examples of deception in the natural world?

Trivers: Tough call. They are so numerous, intricate and bizarre. But you can hardly beat female mimics for general interest. These are males that mimic females in order to achieve closeness to a territory-holding male, who then attracts a real female ready to lay eggs. The territory-holding male imagines that he is in bed (so to speak) with two females, when really he is in bed with one female and another male, who, in turn, steals part of the paternity of the eggs being laid by the female. The internal dynamics of such transvestite threesomes is only just being analyzed. But for pure reproductive artistry one can not beat the tiny blister beetles that assemble in arrays of 100’s to 1000’s, linking together to produce the larger illusion of a female solitary bee, which attracts a male bee who flies into the mirage in order to copulate and thereby carries the beetles to their next host.

Cook: At what age do we see the first signs of deception in humans?

Trivers: In the last trimester of pregnancy, that is, while the offspring is still inside its mother. The baby takes over control of the mother’s blood sugar level (raising it), pulse rate (raising it) and blood distribution (withdrawing it from extremities and positioning it above the developing baby). It does so by putting into the maternal blood stream the same chemicals—or close mimics—as those that the mother normally produces to control these variables. You could argue that this benefits mom. She says, my child knows better what it needs than I do so let me give the child control. But it is not in the mother’s best interests to allow the offspring to get everything it wants; the mother must apportion her biological investment among other offspring, past, present and future. The proof is in the inefficiency of the new arrangement, the hallmark of conflict. The offspring produces these chemicals at 1000 times the level that the mother does. This suggests a co-evolutionary struggle in which the mother’s body becomes deafer as the offspring becomes louder.

After birth, the first clear signs of deception come about age 6 months, which is when the child fakes need when there appears to be no good reason. The child will scream and bawl, roll on the floor in apparent agony and yet stop within seconds after the audience leaves the room, only to resume within seconds when the audience is back. Later, the child will hide objects from the view of others and deny that it cares about a punishment when it clearly does. So-called ‘white lies’, of the sort “The meal you served was delicious” appear after age 5.

Cook: You write that more intelligent children tend to be more deceptive—can you explain this?

Trivers: The experiment was simplicity itself. A child is asked to sit facing away from a box. The experimenter puts something in the box and says “Do not peek, do not peek” and then leaves the room. Most children peek. The experimenter returns and asks, “Did you peek?” Most children lie—but they do so the more frequently the brighter they are, as judged by a simple cognitive test. If your child is especially bright, he or she lies 100 percent of the time, slow 65 percent of the time. The same thing is true for health at birth. The healthier you are the more apt you are to lie 4 years later.

Cook: How did you become interested in self-deception?

Trivers: I think I was actually interested in the topic in my childhood but in my early ‘20’s I became interested in it in a scientific way. I was studying to become a biologist; a very good friend, to be a psychoanalyst. I was reading Darwin, he was reading Freud. All the time, he was talking about denial, repression, splitting, reaction formation and ego-defense mechanisms. While some of it sounded loony, not all of it did. From everyday life, we know that denial is a powerful force. Why? How on earth could selection favor our wonderful organs of perception only to systematically distort the information to our conscious minds? Where was the pay-off in that? It seemed to challenge the Darwinian paradigm at its core.

Cook: Right, the advantages of deception seem quite obvious, but what advantage could there possibly be to self-deception—to lying to yourself.

Trivers: This is the key problem that captured me in the 1970’s. I realized that if self-deception made it easier to deceive others, then it could confer an advantage. After all, deception only succeeds when undetected. Otherwise it may have most unfortunate consequences. So I imagined that self-deception easily evolved in the service of deceit—all kinds of improbably organized information to the conscious mind in order the better to fool others.

Cook: And how did self-deception play a role in one of the plane accidents you discuss, the crash of the Air Florida flight outside Washington, DC?

Trivers: In the Air Florida flight, the group size was only two. The pilot repeatedly practiced self-deception, minimizing the danger ahead of time and rationalizing danger warnings during take-off which the co-pilot was pointing out. The latter did not practice self-deception but was weak in the face of the pilot's.

It is a little known but striking fact that 80 percent of all crashes takes place when the pilot is flying, even though statistically he flies about 50 percent of the time. Considerable research suggests that it is the co-pilot's unwillingness of assert himself in the face of pilot error that is at the heart of this fact. Indeed, the worst configuration is to have pilot flying with a co-pilot flying with him for the first time.

Cook: What role does self-deception play in history?

Trivers: History or the writing of history? Obviously, both. It has been said that the victors write the history -- and a thoroughly biased one at that. False historical narratives are false history with a personal bias, excusing past mis-behavior, any need for reparations or, indeed, necessity for changed behavior.

In history the effects of self-deception loom large although giving a coherent account of the many ways would be quite an undertaking. Certainly we know for war that self-deception makes an undue contribution, especially to catastrophic ones, such as the 2003 U.S. war on Iraq. Overconfidence, based partly on underestimating one’s adversary, are common features but in the case of Iraq, deceit and self-deception was also entrained by the need to sell a lousy product for home consumption, so no rational preparation was made for day 2 in Baghdad because such planning drew attention to the costs and uncertainties of the war, which the planners wished to minimize.

Cook: Are there situations where self-deception is positive?

Trivers: It depends on what you mean by positive and to whom. Obviously self-deception had to have been positive for people some of the time in the past for it to have been favored by natural selection (where positive means an increase in personal survival or genetic reproduction). But I believe this positive effect is due to greater deception of others, so from their vantage point self-deception is not positive and at a group level it may, in sum, be negative. In marriages, those that remember continuous improvement, although none in fact occurred, are more likely to report that they are happily married and more likely to stay married, but cause and effect are uncertain.

Cook: If in a Darwinian sense, self-deception is good for us. Why should we even try to fight the impulse? And can we?

Trivers: I personally believe in fighting it because I am against deception. I would rather be honest, or at least try to be. Self-deception only compounds the felony, now lying to two individuals instead of one, and also risking putting one's life on a very shaky foundation, falsehoods constructed for the consumption of others.

Can we? Well, that’s another matter. I have certainly enjoyed only very limited success in curbing my own self-deception. Rich insight after the fact but very little predictive and preventive improvement. That is perhaps a paradox or tragedy of self-deception: We see it in ourselves, and wish we could do better at suppressing it, but we cannot.

Are you a scientist who specializes in neuroscience, cognitive science, or psychology? And have you read a recent peer-reviewed paper that you would like to write about? Please send suggestions to Mind Matters editor Gareth Cook, a Pulitzer prize-winning journalist at the Boston Globe. He can be reached at garethideas AT gmail.com or Twitter @garethideas.