According to the late Harvard University biologist Ernst W. Mayr, the greatest evolutionary theorist since Charles Darwin, “species are groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups.”

Reproductive isolation is the key to understanding how new species form, and many types of barriers can divide a population and split it into two different groups: geographic (such as a mountain range, desert, ocean or river), morphological (a change in coloration, body type or reproductive organs), behavioral (a change in breeding season, mating calls or courtship actions), and others. After isolation, if members of the split populations encounter one another and cannot produce viable offspring that can themselves later successfully interbreed and produce viable offspring (hybrids such as mules are infertile), then these two populations constitute two different species.

Let’s say that a species migrates out of Africa into Europe around 400,000 years ago and becomes reproductively isolated from its ancestral population for the next 320,000 years. It evolves distinctive anatomical features and adaptations for the colder climes. Moreover, even after other descendants of the original ancestral population move into Europe around 80,000 years ago, the skeletons from both groups show no obvious signs of blended characteristics. Modern scientists classify the creatures as two different species.

Then, however, genetic analysis reveals that members of these two species interbred and produced viable offspring that populated Europe and spread eastward as far as China and Papua New Guinea. By Mayr’s definition, these two interbreeding populations are not two species after all, but two sibling subspecies of the original African species. A subspecies has a characteristic appearance and geographic range, Mayr explains, yet he adds this significant qualifier: “It is a unit of convenience for the taxonomist, but not a unit of evolution.”

Thus it is — revealing the identity of my example — that we must reclassify Homo neanderthalensis as Homo sapiens neanderthalensis, a subspecies of Homo sapiens. A comprehensive and technically sophisticated study published in the May 7 issue of Science, “A Draft Sequence of the Neandertal Genome,” by Max Planck Institute evolutionary anthropologists Richard E. Green, Svante Pääbo and 54 of their colleagues, demonstrates that “between 1 and 4% of the genomes of people in Eurasia are derived from Neandertals” and that “Neandertals are on average closer to individuals in Eurasia than to individuals in Africa.” In fact, the authors note, “a striking observation is that Neandertals are as closely related to a Chinese and Papuan individual as to a French individual…. Thus, the gene flow between Neandertals and modern humans that we detect most likely occurred before the divergence of Europeans, East Asians, and Papuans.” In other words, our anatomically hirsute cousins are actually our genetic brothers.

This modified Out of Africa theory holds that around 400,000 years ago a population of hominids migrated northward through the Middle East and into Europe and parts of western Asia. Between 80,000 and 50,000 years ago another population from the ancestral continent journeyed a similar route into the Eurasian landmass, and there the two populations met and mated. We are their descendants. The Neandertal species did not go extinct, because it was never a separate species; instead population pockets of Neandertals died out around 30,000 years ago, whereas other Neandertal populations survived through interbreeding with their modern human brothers and sisters, who live on to this day.

I always suspected that Neandertals and anatomically modern humans interbred, based on a simple observation: humans are the most sexual of all the primates, willing and able to do it just about anywhere, anytime, with anyone (and even with other species if the Kinsey report is to be believed in its findings about farmhands and their animal charges). Given the viable hybrid offspring that the most diverse members of our species have produced as a result of cultural conjoinings through both ancient migrations and modern travel, one has to suspect that close encounters of the corporeal kind occurred not infrequently in those dark and lonely cave nights over the course of those long-gone millennia.

Now that is a tale worthy of a romantic novel, brought to you by science.

In his 1974 commencement speech at the California Institute of Technology, Nobel laureate physicist Richard P. Feynman articulated the foundation of scientific integrity: “The first principle is that you must not fool yourself — and you are the easiest person to fool… After you’ve not fooled yourself, it’s easy not to fool other scientists. You just have to be honest in a conventional way after that.”

Unfortunately, says Feynman’s Caltech colleague David Goodstein in his new book On Fact and Fraud: Cautionary Takes from the Front Lines of Science, some scientists do try to fool their colleagues, and believing that everyone is conventionally honest may make a person more likely to be duped by deliberate fraud. Nature may be subtle, but she does not intentionally lie. People do. Why some scientists lie is what Goodstein wants to understand. He begins by debunking myths about science such as:

• “A scientist should never be motivated to do science for personal gain, advancement or other rewards.”
• “Scientists should always be objective and impartial when gathering data.”
• “Scientists must never believe dogmatically in an idea or use rhetorical exaggeration in promoting it.”
• “Scientists should never permit their judgments to be affected by authority.” These and many other maxims just do not reflect how science works in practice.

Knowing that scientists are highly motivated by status and rewards, that they are no more objective than professionals in other fields, that they can dogmatically defend an idea no less vehemently than ideologues and that they can fall sway to the pull of authority allows us to understand that, in Goodstein’s assessment, “injecting falsehoods into the body of science is rarely, if ever, the purpose of those who perpetrate fraud. They almost always believe that they are injecting a truth into the scientific record.” Goodstein should know because his job as the vice provost of Caltech was to investigate allegations of scientific misconduct. From his investigations Goodstein found three risk factors present in nearly all cases of scientific fraud. The perpetrators, he writes,

1. Were under career pressure;
2. Knew, or thought they knew, what the answer to the problem they were considering would turn out to be if they went to all the trouble of doing the work properly; and
3. Were working in a field where individual experiments are not expected to be precisely reproducible.

To detect fraud, we must first define it, and Goodstein does: “Research misconduct is defined as fabrication, falsification, or plagiarism in proposing, performing, or reviewing research, or in reporting research results.” Next there must “be significant departure from accepted practices of the scientific community.” Then, the misconduct must be “committed intentionally, or knowingly, or in reckless disregard of accepted practices,” and finally, as in any court of law, the fraud charge must be proved by a preponderance of evidence.

Clear-cut cases of fraud include the twin studies of British psychologist Cyril L. Burt (who faked so many twins that he had to fabricate additional twin researchers), the Sloan-Kettering Institute cancer researcher William Summerlin’s experiments on inducing healthy black skin grafts on white mice (which he was caught enhancing with a black felt-tipped pen), physicist Victor Ninov’s alleged discovery of element 118 (predicted by others so he faked data for its existence), and of course the famous Piltdown Man hoax (which turned out to be the jaw of an orangutan dyed to look old). Other cases are not so clear. Martin Fleischmann and Stanley Pons’s “discovery” of cold fusion, Goodstein concludes, was most likely a case of scientists who “convince themselves that they are in the possession of knowledge that does not in fact exist.” This self-deception is distinctly different from deliberate deception. So some scientists sin, it’s true. Given the fiercely competitive nature of research funding and the hardscrabble intensity of scientific status seeking, it is surprising that fraud isn’t more rampant. The reason that it is so rare (compared with, say, corruption in politics) is that science is designed to detect deception (of one’s self and others) through colleague collaboration, graduate student mentoring, peer review, experimental corroboration and results replication. The general environment of openness and honesty, though mythic in its idealized form, nonetheless exists and in the long run weeds out the cheats and exposes frauds and hoaxes, as history has demonstrated.

In his 1776 work An Inquiry into the Nature and Causes of the Wealth of Nations, Scottish moral philosopher Adam Smith identified the cause in a single variable: “the propensity to truck, barter, and exchange one thing for another.” Today we call this free trade or market capitalism, and since the recession it has become de rigueur to dis the system as corrupt, rotten or deeply flawed.

If we pull back and take a long-horizon perspective, however, the free exchange between people of goods, services and especially ideas leads to trust between strangers and prosperity for more people. Think of it as ideas having sex. That is what zoologist and science writer Matt Ridley calls it in his book The Rational Optimist: How Prosperity Evolves. Ridley is optimistic that “the world will pull out of the current crisis because of the way that markets in goods, services and ideas allow human beings to exchange and specialize honestly for the betterment of all.”

Sex evolved because the benefit of the diversity created through the intermixture of genomes outweighed the costs of engaging in it, and so we enjoy exchanging our genes with one another, and life is all the richer for it. Likewise ideas. “Exchange is to cultural evolution as sex is to biological evolution,” Ridley writes, and “the more human beings diversified as consumers and specialized as producers, and the more they then exchanged, the better off they have been, are and will be. And the good news is that there is no inevitable end to this process. The more people are drawn into the global division of labour, the more people can specialize and exchange, the wealthier we will all be.”

In the teeth of the recession and the reality of more than a billion impoverished people in developing countries today, this thesis sounds ripe for skepticism, indeed almost blindly Pollyannaish. But Ridley systematically builds a case through copious data and countless studies that “the vast majority of people are much better fed, much better sheltered, much better entertained, much better protected against disease and much more likely to live to old age than their ancestors have ever been. The availability of almost everything a person could want or need has been going rapidly upwards for 200 years and erratically upwards for 10,000 years before that: years of lifespan, mouthfuls of clean water, lungfuls of clean air, hours of privacy, means of traveling faster than you can run, ways of communicating farther than you can shout,” and with more access to “calories, watts, lumen-hours, square feet, gigabytes, megahertz, light-years, nanometers, bushels per acre, miles per gallon, food miles, air miles, and of course dollars than any that went before.”

Trade does something even more important than enrich our lives. It makes people behave more fairly. In a March 18 article in Science entitled “Markets, Religion, Community Size, and the Evolution of Fairness and Punishment,” University of British Columbia psychologist Joseph Henrich and his colleagues engaged nearly 2,700 people in 15 small communities around the world in two-player exchange games in which one subject is given a sum of money (the equivalent of a day’s pay) and allowed to keep or share some or all of it with another person. You would think that most people would just keep all of the money, but in fact the scientists discovered that members of hunter-gatherer communities shared about 25 percent, whereas members of societies who regularly engage in trade gave away about 50 percent. Although religion was a modest factor in making people more generous, the strongest predictor was “market integration,” defined as “the percentage of a household’s total calories that were purchased from the market, as opposed to homegrown, hunted, or fished.” Why? Because, the authors conclude, trust and cooperation with strangers lowers transaction costs and generates greater prosperity for all involved, and thus concepts of fair trade emerged as part of a larger process of social evolution to maintain mutually beneficial exchanges even when the participants were not bound by kinship, status or other social ties.

In other words, our ancestors had sex with people they knew, but their ideas had sex with strangers, and this form of trade led to trust and prosperity.

HISTORY IS NOT OFTEN THOUGHT OF AS A SCIENCE, but it can be if it uses the “comparative method.” Jared Diamond, professor of geography at the University of California, Los Angeles, and James A. Robinson, professor of government at Harvard University, employ the method effectively in the new book they have co-edited, Natural Experiments of History. (Order the lecture on DVD. Jared Diamond lectured, based on this book, as part of the Skeptics Society’s Distinguished Lecture Series at Caltech.) In a timely study comparing Haiti with the Dominican Republic, for example, Diamond demonstrates that although both countries inhabit the same island, Hispaniola, because of geopolitical differences one ended up dirt poor while the other flourished.

Christopher Columbus’s brother Bartolomeo colonized Hispaniola in 1496 for Spain, establishing the capital at Santo Domingo on the eastern side of the island. Two centuries later, during tensions between France and Spain, the Treaty of Ryswick in 1697 granted France dominion over the western half of the island. Because France was richer than Spain at this time and slavery was an integral part of its economy, it turned western Hispaniola into a center of slave trade with staggering differences in population: about 500,000 slaves in the western side of the island as compared with only 15,000 to 30,000 slaves in the eastern side.

That difference in population pressures, along with France’s hunger to import more timber from Haiti, magnified the influence of geographic factors. Weather fronts for Hispaniola come from the east and dump rain on the Dominican side of the island, leaving the Haitian side naturally drier and with less fertile soils for agricultural productivity. Haiti’s need for farmland and timber rapidly deforested the already sparse trees on its side of the island, with disastrous consequences: soil erosion, loss of timber for building and of wood for charcoal fuel, heavier sediment loads in rivers and decreased watershed protection that reduced the potential for hydroelectric power. This negative feedback cycle of environmental degradation for Haiti set it up for squalor.

When both the Haitians and Dominicans gained their independence in the 19th century, we see other comparative differences. Haitian slave revolts were violent, and Napoleon’s draconian intervention for restoring order resulted in the Haitians distrusting Europeans and eschewing future trade and investments, imports and exports, immigration and emigration. Haitian slaves had also developed their own Creole language spoken by no one else in the world, which further isolated Haiti from cultural and economic exchanges. Collectively, those barriers meant that Haiti did not benefit from factors that typically build capital, wealth and affluence and that might have led to prosperity under independence. In contrast, Dominican independence was relatively nonviolent; the country shuttled back and forth for decades between independence and control by Spain, which in 1865 decided that it no longer wanted the territory. Throughout this period the Dominicans spoke Spanish, developed exports, traded with European countries, and attracted European investors, as well as a diverse émigré population of Germans, Italians, Lebanese and Austrians, who helped to build a vibrant economy.

Finally, even when both countries succumbed to the power of evil dictators in the mid-20th century, Rafael Trujillo’s control of the Dominican Republic involved considerable economic growth because of his desire to enrich himself personally, but his policies led to a strong export industry and imported scientists and foresters to help preserve the forests for his profiteering timber holdings. Meanwhile Haiti’s dictator François “Papa Doc” Duvalier did none of this and instead further isolated the Haitians from the rest of the world.

Diamond acknowledges that many other factors are involved in the long history of this island but that the comparative method, he writes, “consists of comparing— preferably quantitatively and aided by statistical analyses—different systems that are similar in many respects but that differ with respect to the factors whose influence one wishes to study.”

At the heart of all science is the isolation of a handful of powerful factors that account for the majority of the variance in what is being measured. Employing the comparative method with such natural experiments of history is no different from what sociologists and economists do in comparing natural experiments of society today. So it is time for scientists to respect history as a science and for historians to test their historical hypotheses by the comparative method and other techniques.

In the 1922 poem The Waste Land, T. S. Eliot writes, cryptically: Who is the third who always walks beside you? / When I count, there are only you and I together / But when I look ahead up the white road / There is always another one walking beside you.

In his footnotes to this verse, Eliot explained that the lines “were stimulated by the account of one of the Antarctic expeditions [Ernest Shackleton’s] … that the party of explorers, at the extremity of their strength, had the constant delusion that there was one more member than could actually be counted.”

Third man, angel, alien or deity — all are sensed presences, so I call this the sensed-presence effect. In his gripping book, The Third Man Factor (Penguin, 2009), John Geiger documents the effect in mountain climbers, solo sailors and ultraendurance athletes. He lists conditions associated with it: monotony, darkness, barren landscapes, isolation, cold, injury, dehydration, hunger, fatigue and fear. I would add sleep deprivation; I have repeatedly experienced its effects and witnessed it in others during the 3,000-mile nonstop transcontinental bicycle Race Across America. Four-time winner Jure Robic, a Slovenian soldier, recounted to the New York Times that during one race he engaged in combat a gaggle of mailboxes he was convinced were enemy troops; another year he found himself being chased by a “howling band” of black-bearded horsemen: “Mujahedeen, shooting at me. So I ride faster.”

Sleep deprivation also accounts for Charles A. Lindbergh’s sensed presence during his transatlantic flight to Paris: “The fuselage behind me becomes filled with ghostly presences — vaguely outlined forms, transparent, moving, riding weightless with me in the plane … conversing and advising on my flight, discussing problems of my navigation, reassuring me, giving me messages of importance unattainable in ordinary life.”

Whatever the immediate cause of the sensed-presence effect, the deeper cause is to be found in the brain. I suggest four explanations:

1. The hallucination may be an extension of the normal sensed presence we experience of real people around us, perhaps triggered by isolation.
2. During oxygen deprivation, sleep deprivation or exhaustion, the rational cortical control over emotions shuts down, as in the fight-or-flight response, enabling inner voices and imaginary companions to arise.
3. The body schema, or our physical sense of self — believed to be located primarily in the temporal lobe of the left hemisphere — is the image of the body that the brain has constructed. If for any reason your brain is tricked into thinking that there is another you, it constructs a plausible explanation that this other you is actually another person — a sensed presence — nearby.
4. The mind schema, or our psychological sense of self, coordinates the many independent neural networks that simultaneously work away at problems in daily living so that we feel like a single mind.

Neuroscientist Michael S. Gazzaniga of the University of California, Santa Barbara, calls this the left-hemisphere interpreter — the brain’s storyteller that pulls together countless inputs into a meaningful narrative story. In an experiment with a “split-brain” patient (whose brain hemispheres were surgically disconnected), Gazzaniga presented the word “walk” only to the right hemisphere. The patient got up and began walking. When he was asked why, his left-hemisphere interpreter made up a story to explain this behavior: “I wanted to go get a Coke.”

My brother-in-law Fred Ziel, who has twice climbed Mount Everest, tells me that both times he experienced a sensed presence: first when he was frostbitten and without oxygen at the limit of physical effort above the Hillary Step, and second on Everest’s north ridge after he collapsed from dehydration and hypoxia at 26,000 feet. Both times he was alone and feeling desirous of company. Tellingly, when I asked his opinion as a medical doctor on possible hemispheric differences to account for such phenomena, Fred noted, “Both times the sense was on my right side, perhaps related to my being left-handed.” The sensed presence may be the left-hemisphere interpreter’s explanation for right-hemisphere anomalies.

Whatever its cause, the fact that it happens under so many different conditions tells us that the presence is inside the head and not outside the body.

Have you ever died and come back to life? Me neither. No one has. But plenty of people say that they have, and their experiences were the subject of an episode of Larry King Live last December on which I appeared as the token skeptic among a tableful of believers, including CNN’s medical correspondent Sanjay Gupta, New Age author Deepak Chopra, a football referee who “died” on the playing field, and an 11-year-old boy named James Leininger who believes he is the reincarnation of a World War II fighter pilot.

Dr. Gupta started us off by recalling that when he was in medical school the residents were taught to mark the time of death to the minute, when death can often take anywhere from a couple of minutes to a couple of hours to occur, depending on the conditions. As Gupta noted, people who have fallen into frozen lakes and “died” were not quite dead, and their core body temperatures dropped so rapidly that their vital tissues were preserved long enough for subsequent resuscitation. In other words, people who have near-death experiences (NDEs) are not actually dead!

The same definitional problem arose when guest host Jeff Probst (of Survivor fame, fittingly) introduced the football referee: “A man died on a football field seven years ago and came back to life.” Gupta added that he “was dead for two minutes and 40 seconds.” When I was asked for an explanation, I said: “He wasn’t dead! You started this hour off with Sanjay Gupta explaining we can’t say somebody’s dead at one given moment at a particular time on the clock. That’s not how it works. It takes two, three, five, 10 minutes to go through a dying process. The ref wasn’t dead. He was in a near-death state.” In fact, moments after collapsing, the ref had his heart restarted by an automated external defibrillator. There was nothing miraculous to explain.

Fuzzy language is pervasive in such discussions, and no one uses it better than Dr. Chopra, as in this explanation for NDEs: “There are traditions that say the in-body experience is a socially induced collective hallucination. We do not exist in the body. The body exists in us. We do not exist in the world. The world exists in us.” Here is Deepak on death:

Birth and death are spacetime events in the continuum of life. So the opposite of life is not death. The opposite of death is birth. And the opposite of birth is death. And life is the continuum of birth and death, which goes on and on.

When I asked what had happened to little James Leininger’s soul if his body is now occupied by the soul of a World War II fighter pilot, Chopra offered this jewel of Deepakese: “Imagine that you’re looking at an ocean and you see lots of waves today. And tomorrow you see a fewer number of waves…. What you call a person actually is a pattern of behavior of a universal consciousness.” Indicating our host, he continued,

There is no such thing as Jeff, because what we call Jeff is a constantly transforming consciousness that appears as a certain personality, a certain mind, a certain ego, a certain body. But, you know, we had a different Jeff when you were a teenager. We had a different Jeff when you were a baby. Which one of you is the real Jeff?

Jeff looked as confused as I felt. When Gupta was asked how a physician deals with such apparent medical miracles, he fell into the fallacy of the argument from ignorance:

When I was researching this for a long time, I thought I was going to explain it all away physiologically. But things that I heard and validated and subsequently believed convinced me that there were things that I could not explain. There were things that were happening at that moment, that near-death experience moment, that simply could not be explained with existing scientific knowledge.

So what? The fact that we cannot fully explain a mystery with natural means does not mean it requires a supernatural explanation. It just means that we don’t know everything. Such uncertainty is at the very heart of science and is what makes it such a challenging enterprise.

Imagine a time in your life when you felt out of control—anything from getting lost to losing a job. Now look at the Figure 1 on this page. What do you see? Such a scenario was presented to subjects in a 2008 experiment by Jennifer Whitson of the University of Texas at Austin and her colleague Adam Galinsky of Northwestern University . Their study, entitled “Lacking Control Increases Illusory Pattern Perception,” was published in Science.

Defining “illusory pattern perception” (what I call “patternicity”) as “the identification of a coherent and meaningful interrelationship among a set of random or unrelated stimuli … (such as the tendency to perceive false correlations, see imaginary figures, form superstitious rituals, and embrace conspiracy beliefs, among others),” the researchers’ thesis was that “when individuals are unable to gain a sense of control objectively, they will try to gain it perceptually.” As Whitson explained the psychology to me, “Feelings of control are essential for our well-being—we think clearer and make better decisions when we feel we are in control. Lacking control is highly aversive, so we instinctively seek out patterns to regain control—even if those patterns are illusory.”

Figure 1

Whitson and Galinsky sat subjects before a computer screen, telling them that they would be presented with a series of images for which they were to determine the underlying concept. For example, they might see a capital A and a lowercase a, one or both of which could be colored, underlined, or surrounded by a circle or square. Subjects would then generate an underlying concept, such as that all capital As are red or surrounded by a circle. There was no actual underlying concept—the computer randomly combined characteristics and was programmed to tell the subjects that they were frequently either “correct” or “incorrect.” Consequently, the ones hearing that they were often wrong developed a sense of lacking control. In the second part of the experiment subjects were shown 24 “snowy” photographs, half of which contained hidden images such as a hand, horses, a chair or the planet Saturn [see Figure 2], whereas the other half just consisted of grainy random dots. Although nearly everyone saw the hidden figures, subjects in the lack-of-control group saw more figures in the photographs that had no embedded images.

Figure 2

In another experiment Whitson and Galinsky had subjects vividly recall an experience in which they either had full control or lacked control over a situation. The subjects then read scenarios in which the characters’ success or failure was preceded by unconnected and superstitious behaviors, such as foot stomping before a meeting where the character wanted to have ideas approved. The subjects were then asked whether they thought the characters’ behavior was related to the outcome. Those who had recalled an experience in which they lacked control were significantly more likely to perceive a greater connection between the two unrelated events than were those who recalled a controlling situation. Interestingly, the low control subjects who read a story about an employee who failed to receive a promotion tended to believe that a behind-the-scenes conspiracy was the cause.

In their final experiment Whitson and Galinsky gave one group of subjects a sense of control by asking them to contemplate and affirm their most important values in life—a proven technique for reducing learned helplessness. The researchers then presented those same snowy pictures, finding that a comparison group of subjects in a lack-of-control condition with no opportunity for self-affirmation saw more nonexistent patterns than did those in the self-affirmation condition.

In 1976 Harvard psychologist Ellen J. Langer and Judith Rodin, now president of the Rockefeller Foundation, conducted a study in a New England nursing home in which the residents were given plants, but only some had the opportunity to water them. Those residents who were in charge of watering the plants lived longer and healthier lives than the others, even those given plants watered by the staff. The sense of control had the apparent effect on physical health and well-being. Perhaps this is what Voltaire meant at the end of Candide, in the title character’s rejoinder to Dr. Pangloss’s proclamation that “all events are linked up in this best of all possible worlds”: “’Tis well said,” replied Candide, “but we must cultivate our gardens.”

(Illustrations copyright 2010 Matt Collins)

I am, by nature, an optimist. I almost always think things will turn out well, and even when they break I am confident that I can fix them. My optimism, however, has not always served me well. Twice I have been hit by cars while cycling— full-on, through-the-windshield impacts that were entirely the result of my blissful attitude that the street corners I had successfully negotiated hundreds of times before would not suddenly materialize an automobile in my path. Such high-impact, unpredictable and rare events are what author Nassim Nicholas Taleb calls “black swans.” Given enough time, no upward sloping trend line is immune from dramatic collapse.

A bike crash as a black swan is, in fact, an apt metaphor for what the investigative journalist and natural-born skeptic Barbara Ehrenreich believes happened to America as a result of the positive-thinking movement. In her engaging and tightly reasoned book Bright-Sided (order on DVD Ehrenreich’s lecture at Caltech), she shows how the positive-psychology movement was born in the halcyon days of the 1990s when the economy was soaring, housing prices were skyrocketing, and positive-thinking gurus were cashing in on the motivation business. Academic psychologists, armed with a veneer of scientific jargon, wanted in on the action.

The shallow bafflegab of such positive-thinking pioneers as Norman Vincent Peale (The Power of Positive Thinking, 1952) and Napoleon Hill (Think and Grow Rich, 1960) or the “prosperity gospel” preachings of such contemporary “pastorpreneurs” as Frederick “Reverend Ike” Eikerenkoetter, Robert Schuller and Joel Osteen are predictably data-light and anecdote-heavy. But one expects better of respected experimental psychologists such as Martin E. P. Seligman, who almost singlehandedly launched the positive-psychology movement in academia that is, according to the Positive Psychology Center website, “the scientific study of the strengths and virtues that enable individuals and communities to thrive.” Ehrenreich systematically deconstructs—and then demolishes—what little science there is behind the positive psychology movement and the allegedly salubrious effects of positive thinking. Evidence is thin. Statistical significance levels are narrow. What few robust findings there are often prove to be either nonreplicable or contradicted by later research. And correlations (between, say, happiness and health) are not causations. Seligman and his colleagues drank the positive-thinking Kool-Aid, Ehrenreich shows, but she provides the antidote.

Take Seligman’s “happiness equation” (physics envy lives!): H = S + C + V (Happiness = your Set range + the Circumstances of your life + the factors under your Voluntary control). As Ehrenreich notes, “if you’re going to add these things up you will have to have the same units [of measurement] for H (happy thoughts per day?) as for V, S, and C.” When she confronted Seligman with this problem in an interview, “his face twisted into a scowl, and he told me that I didn’t understand ‘beta weighting’ and should go home and Google it.” She did, “finding that ‘beta weights’ are the coefficients of the ‘predictors’ in a regression equation used to find statistical correlations between variables. But Seligman had presented his formula as an ordinary equation, like E = mc², not as an oversimplified regression analysis, leaving himself open to literal-minded questions like: How do we know H is a simple sum of the variables, rather than some more complicated relationship, possibly involving ‘second order’ effects such as CV, or C times V?” We don’t know, thereby rendering the equation nothing more than a slogan gussied up in math.

Isn’t positive thinking better than negative thinking? All other things being equal, sure, but the alternative to being either an optimist or a pessimist is to be a realist. “Human intellectual progress, such as it has been, results from our long struggle to see things ‘as they are,’ or in the most universally comprehensible way, and not as projections of our own emotions,” Ehrenreich concludes. “What we call the Enlightenment and hold on to only tenuously, by our fingernails, is the slow-dawning understanding that the world is unfolding according to its own inner algorithms of cause and effect, probability and chance, without any regard for human feelings.”

Feelings matter, of course, but the first principle of skepticism is not to fool ourselves, and feelings—both positive and negative—too often trump reason. In the end, reality must take precedence over fantasy, regardless of how it makes us feel.

Humans are, by nature, tribal and never more so than in politics. In the culture wars we all know the tribal stereotypes of what liberals think of conservatives: Conservatives are a bunch of Hummer-driving, meat-eating, gun-toting, hard-drinking, Bible-thumping, black-and-white- thinking, fist-pounding, shoe-stomping, morally hypocritical blowhards. And what conservatives think of liberals: Liberals are a bunch of hybrid-driving, tofu-eating, tree-hugging, whale-saving, sandal-wearing, bottled-water-drinking, ACLU-supporting, flip-flopping, wishy-washy, namby-pamby bed wetters.

Like many other stereotypes, each of these contains an element of truth that reflects an emphasis on different moral values. Jonathan Haidt, who is a psychologist at the University of Virginia, explains such stereotypes in terms of his Moral Foundations Theory (see www.moralfoundations.org), which he developed “to understand why morality varies so much across cultures yet still shows so many similarities and recurrent themes.” Haidt proposes that the foundations of our sense of right and wrong rest within “five innate and universally available psychological systems” that might be summarized as follows:

1. Harm/care: Evolved mammalian attachment systems mean we can feel the pain of others, giving rise to the virtues of kindness, gentleness and nurturance.
2. Fairness/reciprocity: Evolved reciprocal altruism generates a sense of justice.
3. Ingroup/loyalty: Evolved in-group tribalism leads to patriotism.
4. Authority/respect: Evolved hierarchical social structures translate to respect for authority and tradition.
5. Purity/sanctity: Evolved emotion of disgust related to disease and contamination underlies our sense of bodily purity.

Over the years Haidt and his University of Virginia colleague Jesse Graham have surveyed the moral opinions of more than 110,000 people from dozens of countries and have found this consistent difference: self-reported liberals are high on 1 and 2 (harm/ care and fairness/reciprocity) but are low on 3, 4 and 5 (in-group loyalty, authority/respect and purity/sanctity), whereas self-reported conservatives are roughly equal on all five dimensions, although they place slightly less emphasis on 1 and 2 than liberals do. (Take the survey yourself at www.yourmorals.org.)

Instead of viewing the left and the right as either inherently correct or wrong, a more scientific approach is to recognize that liberals and conservatives emphasize different moral values. My favorite example of these differences is dramatized in the 1992 film A Few Good Men. In the courtroom ending, Jack Nicholson’s conservative marine Colonel Nathan R. Jessup is being cross-examined by Tom Cruise’s liberal navy Lieutenant Daniel Kaffee, who is defending two marines accused of accidentally killing a fellow soldier. Kaffee thinks that Jessup ordered a “code red,” an off-the-books command to rough up a disloyal marine trainee in need of discipline and that matters got tragically out of hand. Kaffee wants individual justice for his clients. Jessup wants freedom and security for the nation even at the cost of individual liberty, as he explains:

“Son, we live in a world that has walls. And those walls have to be guarded by men with guns…. You don’t want the truth because deep down, in places you don’t talk about at parties, you want me on that wall. You need me on that wall. We use words like honor, code, loyalty. We use these words as the backbone to a life spent defending something. You use ’em as a punch line. I have neither the time nor the inclination to explain myself to a man who rises and sleeps under the blanket of the very freedom I provide, then questions the manner in which I provide it.”

Personally, I tend more toward the liberal emphasis on individual fairness, justice and liberty, and I worry that overemphasis on group loyalty will trigger our inner xenophobias. But evolutionary psychology reveals just how deep our tribal instincts are and why good fences make good neighbors. And I know that ever since 9/11, I am especially grateful to all the brave soldiers on those walls who have allowed us to sleep under a blanket of freedom.

What are the odds that intelligent, technically advanced aliens would look anything like the ones in films, with an emaciated torso and limbs, spindly fingers and a bulbous, bald head with large, almond-shaped eyes? What are the odds that they would even be humanoid? In this YouTube video, produced by Josh Timonen of the Richard Dawkins Foundation for Reason and Science, I argue that the chances are close to zero. Richard Dawkins himself made this interesting observation in a private communication after viewing it:

I would agree with [Shermer] in betting against aliens being bipedal primates, and I think the point is worth making, but I think he greatly overestimates the odds against. [University of Cambridge paleontologist] Simon Conway Morris, whose authority is not to be dismissed, thinks it positively likely that aliens would be, in effect, bipedal primates. [Harvard University biologist] Ed Wilson gave at least some time to the speculation that, if it had not been for the end-Cretaceous catastrophe, dinosaurs might have produced something like the attached [referring to paleontologist Dale A. Russell’s illustrated evolutionary projection of how a bipedal dinosaur might have evolved into a reptilian humanoid].

I replied to Dawkins that if something like a smart, technological, bipedal humanoid has a certain level of inevitability because of how evolution unfolds, then it would have happened more than once here. In his 2001 book Nonzero: The Logic of Human Destiny, Robert Wright argues that our existence precludes other terrestrial intelligences of our level from arising. But Neandertals were as close as one can get to a counterfactual experiment: they had hundreds of thousands of years to themselves in Europe without our interference and showed nothing like the technological and cultural progress of the modern humans who displaced them. Dawkins’s rejoinder to me is enlightening:

But you are leaping from one extreme to the other. In the film vignette, you implied a quite staggering rarity, so rare that you don’t expect two humanoid life-forms in the entire universe. Now you are … pointing out, correctly, that a certain inevitability would predict that humanoids should have evolved more than once on Earth! So, yes, we can say that humanoids are fairly improbable, but not necessarily all that improbable! Anything approaching “a certain inevitability” would mean millions or even billions of humanoid life-forms in the universe, simply because the number of available planets is so huge. Now, my guess is intermediate between your two extremes … I suspect that humanoids are not so very rare as to justify the statistical superlatives that you permitted yourself in the vignette.

Good point. But of the 60 to 80 phyla of animals, only one, the chordates, led to intelligence, and only the vertebrates actually developed it. Of all the vertebrates, only mammals evolved brains big enough for higher intelligence. And of the 24 orders of mammals only one — ours, the primates — has technological intelligence. As the late Harvard evolutionary biologist Ernst Mayr concluded: “Nothing demonstrates the improbability of the origin of high intelligence better than the millions of phyletic lineages that failed to achieve it.” In fact, Mayr calculated that even though there have evolved perhaps as many as 50 billion species on Earth, “only one of these achieved the kind of intelligence needed to establish a civilization.”

The late astronomer Carl Sagan, in a Planetary Society debate with Mayr (Bioastronomy News, Vol. 7, No. 4, 1995), noted that technologically communicating species “may live on the land or in the sea or air. They may have unimaginable chemistries, shapes, sizes, colors, appendages and opinions. We are not requiring that they follow the particular route that led to the evolution of humans. There may be many different evolutionary pathways, each unlikely, but the sum of the number of pathways to intelligence may nevertheless be quite substantial.”

Thus, the probability of intelligent life evolving elsewhere in the cosmos may be very high even while the odds of it being humanoid may be very low. I strongly suspect that we are blinded by Protagoras’ bias (“Man is the measure of all things”) when we project ourselves into the alien Other.