The HuffPo has, they claim, a specific editorial policy against promoting “conspiracy theories.” It is selectively enforced.

But publishing the new agey holistic naturopath crystal-healing Beverly Hills quack-to-the-stars bullshit of Arianna’s good friend’s nutritionist is one (stupid, potentially dangerous) thing. Giving a platform to the anti-science creationist dingbats at The Discovery Institute is a step in a darker direction.

The Discovery Institute aims to make kids learn about “Intelligent Design,” a thing evangelical Christians invented because they were sick of getting made fun of for saying out loud that they believe that Adam and Eve rode dinosaurs. “Intelligent Design” has no basis in science — indeed, it is a sick parody of science — and the motivations behind getting into classrooms are purely political.

As part of their “Religion and Science” feature (which looks to be a lot of fashionable mysticism from the usual pop-philosophy hacks — like good ol’ Deepak Chopra) the HuffPo published a post from Discovery Institute Senior Fellow David Klinghoffer blaming Darwin for eugenics and the Nazis.

This is cancerous bullshit. Professional anti-science propagandists like Klinghoffer are free to write and publish it, but no one with any respect for their readers or sense of responsibility to the truth should promote it.

Scientist and science writer Eric Michael Johnson responded to Klinghoffer, on the Huffington Post.

Here’s how his last paragraph reads:

The Nazi policies enacted three-quarters of a century ago this month were certainly bad enough, we don’t need to spread the blame onto those who had no connection with them. Creationists do a poor service to the memory of Holocaust victims by using their deaths in a politically motivated attack against science. David Klinghoffer, his fellow creationists, and those who give them a platform should be ashamed of themselves for pushing and allowing a tactic rejected by a US federal court judge as “breathtaking inanity” should be strongly criticized.

Here’s how the last sentence originally read:

David Klinghoffer and his fellow creationists should be ashamed of themselves, and the decision by Huffington Post to give a platform to an organization pushing a tactic rejected by a US federal court judge as “breathtaking inanity” should be strongly criticized.

Giving a space to quacks to sell vitamin supplements to morons is insulting enough, but actually allowing a shameless asshole like Klinghoffer to use the Holocaust to promote his right-wing crusade to teach children lies is beyond the pale. Platform or no, there’s no reason for anyone rational or even anyone with a sense of shame to continue giving Huffington free content.

But if the university has a policy permitting the distribution of any “noncommercial materials,” why not just hand out straightforward religious tracts, without the risk of spreading evolutionary theory yourself? Cameron makes several false and misleading claims at the beginning of the video about how “our kids” aren’t allowed to “pray in public” or to “freely open a Bible in school.” (In fact, the first time I ever read the Old Testament was, yes, for a class at U.C. Berkeley.) Printing a tract as a foreword to “The Origin of Species” is supposed to be a clever end run around this sort of “censorship,” but then Cameron himself indicates that the censorship isn’t actually happening since it’s against university rules.

As for Comfort’s introduction, it says very little about “The Origin of Species” per se, limiting itself to familiar creationist canards about the complexity of the human eye and the absence of “transitional forms” from the fossil record. (It’s hard to lend much credence to the scientific arguments of a guy who thinks chimpanzees are monkeys.) There’s a brief biographical section on Darwin’s life, most of which has been plagiarized from a short text by Dr. Stan Guffey, as some bloggers have demonstrated. The rest has been plagiarized from Brian Regal’s introduction to the Barnes and Noble edition of “The Autobiography of Charles Darwin,” except for a timeline, which was plagiarized from an online resource. Nearly half of the introduction isn’t even about evolution at all, and consists of a hodgepodge of strained sky-diving metaphors and horror stories about pedophiliac killers.

Lastly, although Comfort claimed in advance that “not one jot or tittle” of the text of “The Origin of Species” would be missing from his edition, four entire chapters were omitted. Comfort said that this was an error limited to the first printing, but his critics have claimed that these sections were intentionally left out because they contain strong evidence for Darwin’s theory.

Perhaps, but that presupposes that Comfort actually expects students to read the books his minions distributed. Any college professor can tell you how difficult it is to get students to do the assigned reading, let alone plow through a 19th-century scientific treatise that isn’t even on the syllabus. Look just a little harder and you can tell that Origin Into Schools has nothing to do with books, reading, the intellectual formation of what Cameron calls “our future doctors, lawyers and politicians” or the free exchange of ideas.

The Living Waters Web site reveals Comfort to be obsessed with goading atheists, specifically Richard Dawkins, who is featured in almost as many of the site’s videos as Comfort is and whom Comfort has challenged to a public debate. (Dawkins has refused on the grounds that Comfort is an “ignorant fool,” but some negotiation appears to be ongoing.) Dawkins nicknamed him “Banana Man,” after Comfort used the handy snacking features of the fruit to argue for intelligent design. Comfort recently sent Dawkins an anonymous “gift basket” containing his edition of “The Origin of Species” plus a banana, and said, with regard to the proposed debate, “I think I can smell English chicken.”

Apart from the Cameron video, the main mention of Origin Into Schools on the Living Waters home page consists of an article titled “Origin of Species Campaign Enrages Atheists.” The article announces that Comfort has stopped answering questions about the project because of an “angry backlash” and quotes with obvious relish opponents (including Dawkins) who recommend ripping Comfort’s introduction out of the book, as well as a few who suggest burning it. The site invites comments, the majority of which come from critics, then cherry-picks the most inflammatory to illustrate how “filled with hatred” atheists are.

If the true intention of Origin Into Schools is to introduce college students to creationism, Living Waters seems remarkably uninterested in finding out whether this has been achieved. It dedicates itself to presenting Comfort as assaulted by mouth-frothing atheists who advocate book-burning (just like Hitler!) but who haven’t got the balls to put their ideology to the test of a public debate. Not coincidentally, another regular feature of the Living Waters site is a department called “Christian Persecution News.”

What all this drama is actually designed to produce is donations, which will “expand this give-away to many more universities.” The greater the heathen rage against Comfort and projects like Origin Into Schools, the deeper the faithful will dig into their pockets to support him. It’s also worth noting that the more Comfort grandstands for creationism, the more essential Dawkins’ combative response appears to be. (Dawkins, like Comfort, has a new book out this fall.) In a culture war that more and more comes to resemble the bouts of the World Wrestling Federation, the two have formed a relationship that could even be called symbiotic. Nature is full of bizarre survival mechanisms, as Darwin himself could surely have testified, but politics produces even stranger ones every day.

At the ribbon cutting, Ken Ham, the rugged-faced CEO and president of Answers in Genesis, the nonprofit ministry that built the museum, tells an enthusiastic crowd that the Creation Museum will undo the damage done 82 years ago when Clarence Darrow put William Jennings Bryan on the stand in the famous Scopes trial in Dayton, Tenn. “It was the first time the Bible was ridiculed by the media in America, and that was a downward turning point for Christendom,” Ham says. “We are going to undo all of that here at the Creation Museum. We are going to answer the questions Bryan wasn’t prepared to, and show that belief in every word of the Bible can be defended by modern science.”

The Book of Genesis, that famous first chapter of the Bible, which Ham’s group has interpreted to claim that the universe was created in six 24-hour days a mere 6,000 years ago, serves as the blueprint for the museum. Astronomy, geology and evolution, as they are commonly understood in mainstream science, have no place here. As Ham later tells me, the conclusions of modern science are not to be trusted, as they are biased by the fickle reasoning of man and a modern antagonism toward faith. On the other hand, he says, the Book of Genesis is true “from the first word to the last.”

With a staff of nearly 300 employees, Answers in Genesis, devoted to “Biblical apologetics,” produces a daily radio program fed to 860 stations, operates a Web site instructing visitors how to out-argue Darwinists, and organizes about 300 traveling lectures each year. It’s also a well-oiled money-raising machine and opened the $27 million museum without a penny of debt to banks or lenders.

The museum is situated in Petersburg, Ky., just 20 miles southwest of Cincinnati, an area chosen in large part because it’s within a one-day drive for two-thirds of the country or 200 million Americans. Recent polls show that 40 percent of all Americans would feel at home with the views put forth in the Creation Museum. Only about an equal percentage accept the underlying message of the country’s mainstream science museums. Only 39 percent answer yes to the question, “Do you believe that human beings as we know them developed from earlier species of animals?”

The museum’s 49 acres of carefully landscaped grounds are encircled by a tall metal fence. Visitors tempted to enter without paying will be discouraged by armed guards in black state-trooper-like uniforms and attack dogs. On Monday, just outside the fence, a group of 50 die-hard atheists and skeptics are gathered in the light rain under a “Rally for Reason” banner. Overhead, a small airplane pulls a sign that says, “Thou Shalt Not Lie.” Edwin Kagin, national legal director for American Atheists, explains that as far as he’s concerned, AIG “can teach that things fall up if they want. But we want to make it clear that this nonsense is not accepted by those who do not share its fundamentalist religious views. They are trying to drag us back to the Dark Ages.”

Among the damp roadside protesters is Lawrence Krauss, author and physics professor at Case Western Reserve University in Cleveland, and a member of the advisory board of Defcon: Campaign to Defend the Constitution, the group that paid for the airplane tugging around the Seventh Commandment. Krauss calls the museum “anti-science” and says it reflects an erosion of American science education, posing “a threat to American kids already struggling just to get the basic concept of what science is and how it works.”

Inside, the museum is organized according to the “Six C’s of History”: creation, corruption, catastrophe, confusion, Christ, and the final C, consummation, which isn’t given much time or space in the exhibits because there still isn’t consensus on just how the apocalypse will come down or who goes to heaven and when. At the Creation exhibit, two young T. rexes peacefully watch fish swim in a placid pond. Two curly-haired robotic kids play nearby. In any other place, this would be the setup for a massacre. But this pre-Noah’s-flood Jurassic Park is benign. The animals are vegetarians and plants don’t have thorns. The fossil record, says the museum, confirms all of this.

Mark Looy, co-founder of Answers in Genesis, is walking me through the museum. He explains that the great flood is responsible for the fossil record. Plants and animals are distributed in different strata based not on the time of their formation, but on where the flood waters moved them before receding. Those areas where no thorns or other defensive or hostile plants are found, he explains, are pre-flood forms.

Later Ham tells me that his skeptics, who cling to the “millions of years” theory, are wrong about when dinosaurs stalked the Earth. He cites a recent discovery of intact blood vessels in some T. rex tissue, suggesting that the finds are only thousands of years old, not 65 million, as paleontologists say. “They will try to come up with an explanation to keep the fossils old,” says Ham, “but we don’t need to. The explanation of their age is already right there in the Bible.”

For generations, paleontologists have shown that dinosaurs and humans never trod the Earth at the same time, that in fact with the exception of birds (modern-day dinosaurs), they never got within 60 million years of each other on the timeline of natural history. Not so, says Looy. “They all had to exist at the same time because they were all made on the same day. There may not be any fossil evidence showing dinosaurs and people in the same place at the same time. But it is clearly written that they were alive at the same time.”

In the Garden of Eden in Genesis, says Ham, when everything was still perfect, animals weren’t predators or prey, so the museum’s designer, Patrick Marsh, is able to crowd grizzly bears, wildcats, zebras, kangaroos, an iguanodon and several other dinosaurs into the same little chunk of primeval Eden. After the fall, such a scene would result in a bloody mess.

Buddy Davis, a technician and artist who has also made dinosaurs for use in secular exhibits, tells me he’s much happier seeing his dinosaurs at the Creation Museum, promoting faith in the Bible. “I want to see God get credit for his creation,” he says. “I look around and see so much beauty — even if it is marred by sin — and to think that it all just came from an explosion billions of years ago is just wrong. To me it’s obvious the hand of God is behind it. As scripture says, ‘They are without excuse’ who do not believe.”

The Garden of Eden presents a series of scenes down a “trail of life.” In the first, a bearded, dark-haired Adam beckons to a mountain lion with one outstretched arm, while the other is wrapped around a little lamb. Smaller animals appear drawn to Adam, who is perhaps naming them, God’s first assignment for him. A bit farther along we’re introduced to Eve, looking like a great big brown Barbie and staring intently into Adam’s eyes. Adam and Eve are naked, and Maggie and Tom Thorne, a pair of Christians visiting from Michigan, are smiling at the scene. They agree it seems a little unfair for God to expect two such well-designed specimens not to get around to sinning pretty quickly. A few yards further we see Adam and Eve again, this time standing in a pool of water, their genitals coyly obscured by lily pads. Now they definitely appear to be grappling with the chemistry that will get them in big trouble.

An oversize cobra-like snake makes an appearance, and before you know it, Eve is holding grape-size, blood-colored fruits in her outstretched hand, offering knowledge of good and evil to a flummoxed-looking Adam. “We’re not sure what kind of fruit it was, but we do know it wasn’t an apple,” says Looy, perhaps to demonstrate the kind of questions the several Ph.D. researchers at the museum are now toiling over in the labs behind the walls of the exhibition space.

In the next scene, after the fall from grace, Adam and Eve, looking far less happy than before, are standing next to two lambs they have slaughtered on a sacrificial stone table. The sacrifice has a practical value — the original couple are now wearing lambskin suits and the lambs are skinless — and a spiritual one; the lambs are sacrificed, a visitor explains to me, in partial payment for the debt incurred by Adam and Eve for eating the fruit of knowledge. I tell the visitor it seems unfair for the lamb to pay for their mistake. “Well, it wasn’t enough,” he says. “God had to send his only Son to pay the ultimate price for their sin.” When I tell him that sounds kind of extreme, he looks at me and shakes his head slowly a couple of times before moving on.

Inside the Garden of Eden, Nancy Senai, who is visiting from Lansing, Mich., tells me, “It feels pretty nice to have something that is for God and about God, instead of all the evolution in other places.” I ask her if she thinks the history presented here is true. “God said it clearly, and I believe it the way he said it,” she says. “Everything else is uncertain.”

The great flood, which washed away all life on earth, is the key to understand the Catastrophe exhibit and the museum’s version of natural history. After Adam and Eve’s original sin, God told Noah to build an ark. He sent him two of every kind of land animal to repopulate the earth. Visitors to the museum walk among robotic representations of Noah and his building crew as they construct a supposedly full-scale section of the boat. After Noah has invited his sinning neighbors onto the ark and warned them of the coming flood, they mock him or are dissuaded from heeding his advice by the small pressures of daily life. The door slides shut and they are left behind to drown in the 40-day deluge that formed everything we see on Earth today, from Mt. Everest to Death Valley.

In Ham’s view, the great flood explains not only where scientists find fossils today but also the topography of the modern world. The Grand Canyon, he informs me, was made in a matter of days or weeks as the waters of the flood rushed away and the land was reclaimed. In the exhibit, you walk through a winding canyonlike corridor with spinning, dizzying lights into a wide-open room with videos, exhibits and diagrams explaining the hydrology of instant canyon-making. Ham says that instant canyon-making is based on the fact that volcanoes, such as Mount St. Helens, created reservoirs of water for a time in their altered topography. When those reservoirs breached, deep grooves were cut by the flowing water, leading to the fast formation of canyons.

After the flood, Noah’s descendants multiply again on Earth, but not quickly or broadly enough to satisfy God, who then introduces a slew of new languages to drive people apart, resulting in their dispersal around the globe. The ensuing C-for-Confusion theme is represented through a gritty and menacing back alley postered with newspaper headlines about the rise in abortion, drug use, homosexuality and teen suicide.

The entire exhibit, in fact, is awfully grim. A montage slide show of fetuses, starving kids, swastikas, tourniquet-bound arms ready for the needle bombard the wall in a room with a soundtrack of blaring sirens, boots marching in unison, and crying kids. In the middle of this urban mess is a big wrecking ball with the words “Millions of Years” carved into it. Ham blames the notion that the Earth is quite a bit older than the Bible suggests for just about all the world’s problems. Evolution, which requires large amounts of time for small changes to accumulate into larger ones, makes it far too easy for people not to believe the Bible, he says. And that loss of belief “is at the root of modern evil.”

Inside the Confusion exhibit, I strike up a conversation with Tim Shaw, a high school student visiting from Florida. “I don’t care how long it took to make the Grand Canyon,” he tells me. “It’s not how old it is that matters to me. What matters is being right with God. Darwin’s theory has no God. It can’t be right. I don’t know if this story is truer than Darwin’s theory, but I do know it’s better.”

Shawn is a composer of classical music, but may be better known as the son of famous New Yorker editor William Shawn and the younger brother of actor and playwright Wallace Shawn (of “My Dinner With Andre” and “The Princess Bride,” among many other projects). The matter of his family name is not merely one of pedigree. His upbringing, as “Wish I Could Be There” shows, encouraged whatever genetic predisposition to anxiety he had. His was a childhood marked by an excess of the usual secrets and lies. There was the matter of the Shawns’ “ambivalence” toward their Jewishness — his mother preferred to identify with her Swedish side rather than her Russian side, and William and one of his brothers changed their name from “Chon” to the decidedly more Anglo “Shawn.” There was his mentally ill twin sister, Mary, who, at the age of 8, was sent to a home and seen only once a year.

Then there was his father’s own agoraphobia, never discussed among the family but probably inherited and modeled by his son. (William persuaded his office building to maintain one manually operated elevator for his use.) There was his mother’s terror of storms, and her habit of ruling little Allen’s life with a ferocity matched only by her back-seat driving in taxicabs. And finally, there was the matter of his father’s double life with a second “wife,” New Yorker writer Lillian Ross. He interrupted road trips for surreptitious visits to phone booths; at home he took Ross’ calls on a separate line, vanishing into a closet with the receiver. Yet Shawn did not learn of his father’s lifelong affair until he was almost 30, when, he told the New York Times, someone “a bit angry at men … mentioned it in the context of a speech in which she was speaking disparagingly of the way men behave.”

The name “Lillian Ross” is conspicuously absent from “Wish I Could Be There”; so is Jamaica Kincaid, Allen’s ex-wife, with whom he has two children. For a man from such a famous family, of whom so much is known, the tactful silence seems almost too coy. But even in this quasi memoir, Shawn wants his privacy. Indeed, as an agoraphobic — someone who is afraid of both open spaces and enclosed places, who, when asked what he is afraid of, might plausibly reply “everything” — he is obsessed with control and dreads revealing more of himself than he must. “Severe phobias can bring with them the fear of discovery and of becoming an outcast,” he writes. “Shame begins inside, with being afraid to admit, even to oneself, that one is in some respects hampered.”

Shawn argues, rather sensibly, that while phobics are predisposed to their anxieties, those anxieties may be triggered and conditioned by environment and experience. “Wish I Could Be There” uses science, clearly put into layman’s terms, to talk about the relationship between the mind and body during a phobic episode. Shawn reviews some basic biology lessons about how the brain fires and the mind creates an explanation for the sweaty palms and racing heart — a “shoot first, ask questions later” scenario. Once you’re in the midst of responding to fear, your emotions step in to give you a way to think about and understand the panic: This open field must present a danger, otherwise why would I be having trouble breathing? In this way, a phobic’s fears are almost rational; the only other explanation for the body’s sudden attack, after all, would be that you were actually going crazy. The circuit is completed when the desire to explain the fear, to create a story around it, winds up reinforcing it.

There are certainly some weird phobias out there — ephebophobia, fear of adolescents — but the common ones are, Shawn thinks, common for a reason. From Darwin, he gets the idea that our fears are vestiges of evolution, deformed and out of place in modern times: In open spaces, there is nowhere to hide from attack; in the dark, predators lurk around any corner. Phobias are the cure that has become a disease. (Darwin, too, was terribly anxious, and “would awaken trembling in terror in the night,” although in his day he apparently suffered without understanding.)

From Freud, Shawn gets everything else — notions of trauma, memory, repression and, most crucially, “the insight that we carry our past inside us as a permanent present.” He seems eager to redeem Freud’s usefulness, bristling that “new books on the brain seem almost mockingly dismissive” of him. Not so Shawn. He dwells on the case study of 5-year-old Little Hans, who “developed a morbid terror of horses” around the same time that his mother had another baby. Shawn admires Freud for recognizing that “Hans’s phobia was constructed on top of an evolutionarily primed wariness about animals” while understanding it as “Hans’s outlet for the conflicted longings and fears of punishment he hadn’t been able to express in other ways.”

Shawn has a literary mind, and it is no surprise that he’s drawn to such a literary thinker. “Freud’s genius revealed that the infinite resourcefulness of the human mind necessitates a greatly expanded concept of what can constitute ‘danger.’ The fear mechanism constructed for tigers in the forest can be used by humans to fight tigers in the mind.” (Feminists take note: Shawn’s discussion of hysteria makes no mention of Dora, the patient who famously broke off treatment, and whose story Freud published as his own.) The fact that he “never got over the suspicion” that he caused the birth trauma suffered by his sister might explain his phobias: They could be, as Freud thought, displaced anxieties, “a discharge of fear in a safe place.” Still, Shawn wonders, “if phobias are decoys, what will strike us when the decoys are removed? What awaits us in the emptiness of space?”

Shawn’s looping, meandering style, with chapters organized by theme (“Father,” “Conditioning,” “Alone/Not Alone”), sprinkled with anecdotes, invites self-analysis. But Shawn, it must be said, is not a champion storyteller. His subject is always interesting, but his style can be reverie producing. (Occasionally one might reread a paragraph a few times without noticing.) And yet something sinister vibrates underneath. Much like a conversation with an extremely anxious person, the same territory is mined over and over, unearthed from many angles in a search for something — a definitive cause, a cure — that can never be found.

In music Shawn found joy and freedom, the ability to experiment and to be dark and daring. “Some lurching hidden tragic power coursed through me and made me shiver and feel that I had been living a very long time.” And yet the overall tenor of the book is muted and tender, steeped in quiet reverence for fragile attempts to manage fear and muddle through as best we can. Of his father, Shawn writes that he “tended to treat people the way the character Alyosha in Dostoevski’s ‘The Brothers Karamazov’ recommends: ‘like patients in a hospital.’” On the one hand it is true that we are all, as we learned from Freud, sick, and that the best thing we can do with life is help each other through it. On the other hand, we are not, or not only, hospital patients.

Until recently, it’s been impossible to prove or disprove any of these stories. DNA analysis has changed all that, and as New York Times science reporter Nicholas Wade explains in his new book, “Before the Dawn: Recovering the Lost History of Our Ancestors,” in the process it has toppled more than one cherished belief. It turns out, for example, that most Icelanders are probably descended from Norsewomen and that a large proportion of the male population of Britain carries the Y chromosome of the Celtic speakers who were supposedly chased off the land by the Anglo-Saxons. Similar research has established that an astonishing 8 percent of the men living in the vast territory formerly controlled by the Mongol Empire are most likely direct descendants of Genghis Khan.

The power of DNA analysis to nab criminals, exonerate the wrongly convicted and determine a baby’s true paternity has understandably impressed everyone and provided new fodder for trashy daytime talk shows. With “Before the Dawn,” however, Wade goes further, offering a survey of how cutting-edge genetics has been combined with a variety of other sciences to solve, or at least further illuminate, some long-standing puzzles in humanity’s distant — and more recent — past. As with any powerful new technology, it’s easy to get carried away. (My own enthusiasm prompted me to send a sample of my DNA off to one of several new services that offer ancestral DNA analysis, hoping to learn something about the murkier corners of my own genetic heritage, but more on that later.) It’s easy, in other words, to think that because DNA can tell us so much, it can tell us just about anything, and that would be a dangerous mistake indeed.

Here, greatly simplified, is how it works: When sperm and egg combine to create the embryo of a new organism, a whole lot of swapping of genetic code goes on. The DNA that spells you is a salad of code taken from both your mother and your father. Their DNA is a mix of each of their own parents, and so on back into time immemorial. However, a big portion of the DNA in each of our cells isn’t used to make our bodies; this is what’s often called “junk” or “filler” DNA. Both the active and the filler DNA are subject to small, random variations when the code is transferred from one generation to the next; that’s mutation.

The DNA that’s actively involved in making us what we are is subject to “selective pressure.” If a new mutation makes a human being who’s a little bit taller or faster and that change makes the individual more successful in his or her given environment or more attractive to the opposite sex, then that individual will be more likely to survive and to reproduce more plentifully. Over generations, the mutated gene will become more common, a process called natural selection, which (we can only hope) most of us learned about in school.

Filler DNA, however, because it has no input in shaping the physical organism that carries it, isn’t affected by the natural selection process. It still undergoes the occasional mutation, but those mutations simply accumulate over time without doing anything. In particular, two sections of this DNA — the Y chromosome, which men hand down to their sons, and mitochondrial DNA, which women hand down to all their offspring — have been useful to those researching human ancestry. If, say, 10,000 years ago a particular woman was born with a certain mutation in her mitochondrial DNA, all of her children will carry the same mutation in their mitochondrial DNA, and her female children will pass it on to their children. The same is true for a man of the same period born with a mutation in his Y chromosome, although he will only pass it on to his male offspring, who will only pass it on to their male offspring, etc.

By looking at the Y chromosomes and mitochondrial DNA of various populations in various places, scientists can get a good idea of where these genetic lineages began and how they spread over the globe. The most prominent popularizer of this notion is the Oxford geneticist Bryan Sykes, author of “The Seven Daughters of Eve,” in which he employed the fairly kitschy device of naming the seven women from whom all individuals of European origin are descended, and describing their lives as he imagined them. Yes, it sounds very “Clan of the Cave Bear,” but at its heart there’s an intriguing fact: All contemporary humans are part of one of 38 major “haplogroups,” each founded by a single woman.

A few of those lineages stayed in Africa, where human life originated, but everyone else on the planet, Wade reports, is descended from a tiny group of people who migrated out of Africa 50,000 years ago. That group might have consisted of as few as 150 hunter-gatherers, but eventually their descendants spread as far as Australia and North America to populate the world. Researchers lean toward the theory that there was only one migration out of Africa, one little band of people who braved either the coastal edges of the Arabian desert peninsula or the perils of the eastern Mediterranean, which was then occupied by fierce Neanderthal tribes.

The idea of this exodus is irresistibly romantic, but it can’t be said that Wade takes advantage of that. “Before the Dawn” is at best a workmanly account of what is, after all, a field rife with controversies, reversals, ambiguities and political land mines. Still, what the book lacks in vividness it doesn’t exactly make up for in clarity. The descriptions of how DNA works are more difficult to understand than they should be (although the processes are fundamentally hard to grasp). Genetics, unlike, say, quantum physics, is new enough that it hasn’t yet found a great, nonpolemical popular science writer to do it justice.

Nevertheless, Wade has collected many fascinating stories about the creativity and (occasional) hubris of those scientists who have used DNA analysis to study the past. When did human beings first begin to wear clothes? That used to be impossible to estimate, since the clothes themselves have long since crumbled to dust. But when Mark Stoneking, a researcher at the Max Planck Institute for Evolutionary Anthropology in Leipzig, got a notice from his kid’s school about a problem with lice, he had a brainstorm. Body lice, unlike the head lice from which they evolved, have claws “specialized for living in clothing, not grasping the shafts of hair.” Since the lice can’t live for more than 24 hours away from the warmth of a human body, they must have evolved shortly after human beings (whose hairiness has drastically decreased over the millenniums) began to wear clothes. Comparing the DNA of head lice to body lice gave Stoneking a date for when body lice emerged.

But there’s a catch. The kind of analysis Stoneking performed provides only a ballpark figure: 42,000 to 72,000 years ago. That 30,000-year spread may not be much on the scale of the history of life itself, but in human terms, it’s pretty wide. Did this happen before or after our ancestors left Africa, a date estimated at 50,000 years ago? Your guess is as good as mine.

Wade, who is definitely a worshipper at the church of genetic determinism, usually gives equal time to those who offer objections or counterexplanations for historical changes in human behavior, but his preference for genetic theories is plain. The problem is that there is so much ambiguity and wiggle room, so much that is unknown and as yet unprovable about a lot of these questions, that many of the theories touted in “Before the Dawn” are unconvincing.

The more recent the history in question, the more developed the human society you’re talking about, the less possible it becomes to tease out the genetic causes from the cultural ones. As Wade himself points out, culture began to shape genetics at least as early as human beings began to domesticate cattle. Lactose tolerance, the ability of adult humans to digest cow’s milk, is today found in the highest concentration in the regions once occupied by the cultures that first domesticated cattle. So, while it’s easy to credit Wade’s favored theories of early modern human development — that evolution lies behind the transformation from aggressive and warlike hunter-gatherer cultures to more peaceful, settled communities, for example — at a certain point it sure looks like culture started to move faster and more decisively than evolution.

The most self-consciously controversial chapters in “Before the Dawn” concern race and gender, specifically recent efforts to find the genetic significance of both factors. Wade and others of his inclination are quick to blame any criticism of such research on a lily-livered obeisance to p.c. dictates. To some extent, they’re right, since it’s obvious to anyone with any common sense that there are some organic differences between the genders and the races.

Nevertheless, by wrapping themselves in the authority of science, sociobiologists have a tendency to gloss over large patches of their own ignorance. Evolutionary psychologists, for example, have a tendency to blithely theorize about human sexuality when they clearly don’t know much about how human beings really behave sexually. True, there’s not much solid data to be had. It’s difficult to do reliable research on the sexual behavior, both because people tend to lie about it and because institutions (especially the U.S. government) don’t want to get mixed up in such “disreputable” projects.

An example of how comically wrong sociobiologists can go when they don’t realize what they don’t know about sex turns up in “Before the Dawn.” Geneticists testing for hereditary diseases, Wade explains, sometimes discover “nonpaternity cases,” that is, children for whom “the father of record cannot be the biological parent.” Geneticists estimate that as many as 10 percent of American children are not the biological offspring of their purported fathers. This is “surprising,” Wade observes, “in light of the control that women now exert over their reproductive behavior.” In fact, he concludes, it can only be that many of these nonpaternity cases are “deliberate,” an example of women taking advantage of the evolutionary principle of “sperm competition,” by getting inseminated by more than one man at a time.

By this line of reasoning, people with access to birth control rarely get pregnant unintentionally, and women only have unprotected sex with men in order to conceive their children. Do I really need to explain that it’s quite common for women, married and single, to have sex without protection, either because it happens spontaneously or, mostly likely, because they’d prefer to believe that it did? Not to you perhaps, but apparently evolutionary psychologists, despite paying “particular attention to human mating habits,” still haven’t gotten the memo. In instances like these, you have to suspect that the field holds a special attraction for those who are made uncomfortable by the complexity of human behavior.

Strangely, this is the only point in the book where Wade considers contraception, perhaps the most flagrant, if recent, example of how human culture — our technology and our ability to communicate — has interfered with the usual workings of natural selection. In contrast to all evolutionary formulas, the most “successful” members of our species (in terms of health, wealth and status) are now producing fewer offspring. Those kids are more likely to thrive, it’s true, but they’re also more likely to lead to a genetic dead end by not reproducing at all, putting the kibosh on some very selfish genes.

Actually, the evolutionary fix was in as early as the introduction of agriculture. Farming is a survival skill that, recent genetic analysis shows, didn’t allow one population of human beings to obliterate another. Instead, agriculture — an idea and a technology — spread from one population to another, giving every human community that adopted it a powerful edge. Our ability to communicate such ideas advances at blinding speed compared to the slow grinding of natural selection.

Much of the cross-disciplinary theorizing Wade describes in “Before the Dawn” is fascinating, but speculative. Currently in the news and explored in Wade’s book is a recent investigation of the possibility that Ashkenazi Jews might have acquired their susceptibility to certain hereditary diseases as a side effect of an equally hereditary propensity toward high intelligence. As Wade puts it, “The suggestion that one group of people may be genetically more intelligent than another is a sensitive subject, not least because it opens the door to the argument that if some groups are smarter, others may be less so.” The hypothesis is that because European Jews were confined to certain very limited and intellectually demanding professions for around a thousand years, intense selective pressure made this genetically isolated population more “intelligent” (by one standard) via mutations that also made them more vulnerable to some diseases.

Should such research be squelched out of fears that investigations into the possibly genetic superiority of one group will endorse ideologies that insist on the genetic inferiority of others? If so, then would we also argue that, say, the overrepresentation of West Africans in the upper ranks of sports that require sprinting is purely a coincidence or a “cultural construct”? And if you would agree with that, then would you also advocate ignoring the fact that some hereditary diseases strike some races more often than others and that some drugs help some races more than others? That, Wade writes, was the case with a drug called BiDil, which was found to work for heart patients of African ancestry far more than it did others.

“To falter in scientific inquiry would be a retreat into darkness,” Wade writes. Maybe so, but in the past, in matters of race and sex, what presented itself as scientific inquiry has sometimes turned out to be a headlong leap into darkness. A little skepticism seems justified. Human beings are exquisitely suggestible and scientists are themselves only human, so it would probably help if they were willing to admit, for example, that their definition of “intelligence” might be a tad limited.

It also helps to remember that highly speculative genetic theories, however confidently advanced, are embarrassingly subject to reversals. In “Before the Dawn,” Wade describes genetic research that supposedly proves that “Jewish women, unlike Jewish men, do not all come from the same ancestral population,” contrary to long-held Ashkenazi Jewish folk beliefs that the communities of the Jewish Diaspora were established by couples, rather than single Jewish men who married women from local populations. Then, just this January, Wade reported for the New York Times on another set of researchers who have come to exactly the opposite conclusion, finding all Ashkenazi women to be descended from four female Jewish ancestors. The researcher who advanced the original theory, of course, has refused to retract his conclusion.

Why, given all this healthy skepticism about what we can learn from DNA, did I still opt to send off a cheek swab to Family Tree DNA and receive an analysis of some of my own “filler DNA” at the cost of 189 bucks? Except for my mother’s brother, no one on either side of my family has taken much active interest in our genealogy, so unlike a lot of FTDNA’s customers, I’m not trying to fill in any stubborn blanks in a lush family tree. In a way, the preponderance of blanks has made me more curious. (Though not enough so, I guess, to actually do any genealogical heavy lifting.) I suspect that even the most hardcore social constructionist believes deep down that some of who we are is in our blood, so how could I not at least wonder?

Specifically, though, there’s my mother’s late father, a Catholic, with an unusual, vaguely French name that my relatives vaguely believe had been changed from something else. After seeing an old photograph of him with his brother, I became attached to the idea that they looked Jewish. Since my uncle hadn’t been able to find out much about their family, partly due to the changed name, maybe a DNA test would tell me more?

Like a lot of DNA test customers, I suspect, I was in for some disappointment. As a woman, I only have one set of genetic markers to test, my mitochondrial DNA. (Men can have both their Y chromosome and their mitochondrial DNA tested. “That’s not fair!” a perpetually aggrieved friend of mine said when I told her about it; I assured her that science could not be blamed for this one.) More to the point, my maternal grandfather’s contribution to my mother’s genes couldn’t be detected by this test, either. I could learn about my mother’s mother’s mother’s mother and so on back to the late Pleistocene era, but nothing that crossed from one gender to the other. Likewise, although my brother can track our father’s father’s father’s father and so on, our father’s maternal ancestors must remain a mystery, at least to DNA analysis.

The informational materials provided by FTDNA to its customers are impressively dry, a daunting mass of charts, numbers and capital letters that yield only a dribble of juice under only the most extreme pressure. The real value of the service — and others like it — is in its ability to connect amateur genealogists who’ve hit a dead end with possible “cousins.” Through FTDNA you can enter your stats into MitoSearch, an international public database, to find more matches. And you can enter your information anonymously into the databases of a project being conducted by National Geographic to track the ancient history of humankind’s migration across the earth.

I learned that I belong to haplogroup H, a vast lineage to which almost half of all Europeans belong, ranging from Turkey to the United Kingdom. This was noted on a certificate I received, along with a list of my “mutations” — that is, the differences between my mitochondrial DNA and that of an (unnamed) European individual whose DNA is used as a standard, the Cambridge Reference Sequence. Ancestral DNA tests list only those differences in two sections of filler DNA known for their propensity to mutation and therefore for their usefulness as genetic markers.

As goofy as the certificate is, there was something intriguing about seeing that list of numbers (73G, 263G, 309.1C, etc.), like remnants of the Dewey Decimal System, that held, coded within them, the history of a chain of women going back tens of thousands of years. One of these women, some 1,000 generations back, possibly lived in what we now call Spain, and her descendants traveled gradually up the Western coast of Europe, following the retreating glaciers of the last Ice Age, until at some point one of them crossed the English Channel and eventually settled in Scotland, where her daughter’s daughter’s daughter, etc., would give birth to a woman named Mary Cummings, who sometime in the 19th century would emigrate to Prince Edward Island in Canada and become the great-great-grandmother of my grandmother, also named Mary.

I’m not saying that Family Tree DNA helped me picture all this — they’re not much help in that department, but the forums where their customers try to make sense of the results they’ve received and swap tips with other haplogroup members are another matter. That’s where you’ll find the human face of ancestral DNA analysis, where people say encouraging things like “Go T2!” and where the number “16519C” becomes a bond between countless strangers. Fellow haplogroup members call each other “cousin.” People post their mutation lists and, as with all good boards, a few kindly and knowledgeable old hands are usually around to explain the hard parts — which with DNA analysis is pretty much all of the parts.

People turn to this kind of DNA test to see if they can verify rumored Native American ancestry (not unless it’s on the direct matrilineal or patrilineal lines, as one member found to his dismay). African-Americans want to know which part of the mother continent their people were stolen from. Other seekers are adoptees who want to find out about their biological heritage and can’t get information from the authorities. Most poignantly, one member described having been “abandoned at birth.” I’m not sure if a DNA test can knit the gap something like that leaves in a person’s life, but I can understand why it might seem worth trying.

As much as I believe that “families of choice” are as good as any other kind and that people shouldn’t be defined by the past, blood does call out to us. The intricate marvel of DNA is more dazzling than any alleged celestial clockmaker, and the idea that all of this around us — from the skyscrapers of Manhattan and supercolliders to “King Lear” and the Great Wall of China — began with just 150 tough, desperate (and possibly clothed) people deciding to strike out across the Red Sea for parts unknown never ceases to amaze and impress me. Maybe not enough to make a genealogist out of me, but then it turns out I do have one match, with, of all things, a woman named Maria Marana, born in Genoa, Italy, around 1820, and that might be worth checking out.