The book is structured as a set of essays, some of which were previously published in Sagan's column in Parade magazine. Although they address separate topics - a very useful scheme, since it means that you can essentially pick up the book and start reading from any point - they all cohere into a larger argument, on the role that science plays in our society and why it is so essential, now more than ever. Both the practical and esthetic benefits of science, Sagan argues, are immense: it cures poverty by providing the path to economic development and independence; it alerts us to danger when our actions have the potential to negatively impact ourselves or the environment; it encourages the attitude of rational debate that any free society needs; it teaches us about our own origins and our own nature; and it stirs the sense of awe and wonder, giving us more true sources of reverence and spirituality than any set of shallow superstitions ever did.

The first third or so of the book is about the various kinds of pseudoscience that run rampant in our culture. Sagan discusses UFO sightings and alien abductions (and how they relate to witchcraft hysterias and religious visions of the past), the "face on Mars" and other astronomical pseudoscience, faith healing, repressed memories recovered through hypnosis, and many more. This section contains the famous essay "The Dragon in My Garage," an allegory about unfalsifiable claims, and another, "The Fine Art of Baloney Detection," which gives the critical thinker a list of means by which to test extraordinary and fantastic claims, as well as how to recognize common logical fallacies.

The next section of the book segues into a deeper discussion of the nature of science itself. Sagan showcases the self-correcting nature of science by discussing ways in which scientists (including himself) have been wrong in the past - a brave admission which I wish more scientific authors did - and ways in which science gives us dangerous weapons and other tools of destruction, using as a cautionary example the nuclear physicist Edward Teller.

Finally, Sagan delves into the disturbingly poor state of science education in America (a state of affairs that has changed little since this book was written, unfortunately), hypothesizing about its cause and what we might do to fix it, and, more generally, the stereotypes of scientists and science in our society. In a world where we are more dependent than ever on science and technology, with more power than ever to alter our environment deliberately or by accident, it's all the more essential that we have an educated and scientifically literate populace. Frighteningly, the opposite seems true, as public schools and other educational institutions seem to produce dull conformity rather than stimulating the natural sense of wonder. Sagan offers suggestions on how this state of affairs came about - in part, because governments and other vested interests have a reason to discourage skepticism (with a brilliant, and telling, historical analogy to the way slave-holding states made it a crime to teach blacks, free or enslaved, how to read). He also offers a prescription for correcting it and encouraging the natural inquisitiveness of children to grow and thrive.

Despite Carl Sagan's tragic and early death, The Demon-Haunted World remains as true, insightful and relevant as ever. It's one of the relatively few books I believe all atheists and freethinkers must read. Even for those who agree with its message, it contains the definitive set of arguments reinforcing them, and laying out the case for why this candle in the dark is our only chance to see our way clear of the darkness that envelops us and to make our way into a future full of light.

Both groups making up the Republican party tend to oppose science, but for different reasons. The religious conservatives oppose areas of science that infringe on their faith-based conclusions, such as evolution, sex education, and stem-cell research. Business interests oppose science that might lead to regulation of their industries, such as global warming, endangered-species protection, pollution controls, and research into the health impacts of foods and drugs.

Mooney's book explores politically motivated abuse of science in the above-mentioned fields and others, showing how anti-science elements of the GOP have done their damage. Their tactics include stacking scientific advisory committees with ideologues, passing new laws to bury proposed scientific studies in red tape, commissioning contrarian "science" to create a false impression of controversy, and outright suppressing scientific research whose conclusions they disagree with. He also notes how the religious right, and George W. Bush in particular, magnifies scientific uncertainty as an excuse for inaction where it suits their purposes (such as environmental protection), yet ignores it altogether where it does not suit their purposes (such as missile defense).

Finally, Mooney provides a historical account of how the Republican party, once a friend of science, became the party of anti-science. This transformation began in the 1960s, where conservative politicians such as Barry Goldwater first began to rail against the "scientific elite", and escalated in the 1990s with infamous episodes such as the Gingrich Congress' dismantling of the world-renowned Office of Technology Assessment, leading up to the full-blown Republican war on science today. Mooney quotes Republicans such as Russell Train, administrator of the EPA under two Republican presidents, who are dismayed by the direction their party has taken.

The Republican War on Science thoroughly documents how partisan attacks have touched many fields of science; but if I have any complaint, it is that it does not go for the jugular often enough. Mooney's discussion of the Data Quality Act was a case in point: he does not, in my opinion, explain clearly enough why it is bad to someone unfamiliar with how science works. He could have summed up the law's purpose, which is to give well-funded industry groups as many chances as possible to stifle regulation by burying scientific research in legal red tape, in stronger terms. Similar points could be raised about other chapters. Nevertheless, as a source of information and inspiration, this book is worth reading. As one of the reviews on the cover says, it won't make you feel good, but it will make you wiser.

However, the downside of Darwin's dangerous idea is that it seems too mechanical, too impersonal, to have given rise to many of the things we value highly - such as religion, or human consciousness, or our moral sense. Therefore, ever since it was first proposed, there have been scientists and philosophers who have attempted to construct levees to hold back this universal acid, to prevent it from reaching their most cherished convictions. In Dennett's terminology, evolution by natural selection is a crane - a powerful but mechanical tool that can be used to build ever greater things, including even larger cranes. The resisters of this idea instead want a skyhook - a magical attachment point, floating free and unbound above the earth, from which their valued principles can be hung. The idea of miraculous creation by God, for example, is a skyhook, as are less mystical ideas that would nevertheless create a boundary past which evolution could not go.

Much of Dennett's book is targeted at those whom, in his view, are skyhook-seekers, engaging in efforts to keep natural selection from reaching what seems most valuable about us. Some modern intellectuals whom he accuses of this sin include Stephen Jay Gould, Noam Chomsky, John Searle and Roger Penrose. Others, such as Stuart Kauffman, espouse positions that at first seem to contradict Darwin's dangerous idea, but that on a closer look can easily be folded into it as a special case.

It is important to note that this book cannot be read in isolation. Dennett's arguments are often rather technical, and cannot be understood without also understanding the position and arguments of the people he attacks. I lack the technical expertise required to tell if all of Dennett's arguments are correct, though it did seem to my inexpert eye that he scores at least a few strong points (to be fair, some of his targets, such as Gould, fought back spiritedly, and I think the ultimate truth incorporates parts of each side's reasoning). I have not reached a firm conclusion regarding Dennett's strong adaptationist viewpoint, but I do think it has much to recommend it. I appreciate that he recognizes the necessity of giving testable evolutionary explanations, rather than unsupported "just-so" stories.

Dennett's ultimate conclusion is that there is nothing to fear - that Darwin's idea is really not so "dangerous" after all, because evolution does not rob our cherished notions of their meaningfulness. Rather, it explains that meaningfulness and shows how such things could have come about in a natural world, as the end result of a process in which cranes build increasingly larger cranes. He offers an array of audacious hypotheses about the origin of language, morality, meaning, religion and culture, all of which are grounded firmly in a Darwinian framework. Not all of these may turn out to be strictly correct (in particular, I accept the often-raised rejoinder that cultural evolution is not quite as Dennett describes it, because memes evolve in a Lamarckian, not Darwinian, sense), but I expect all of them at the very least have stimulated much discussion and will continue to do so, and on the broad points most of them must be largely accurate.

While creationists and others have bemoaned this book as the embodiment of everything they see as evil about Darwinian thinking, an attentive reading will fail to turn up any danger. Dennett firmly and explicitly rejects the favorite strawmen of religious antievolutionists, including nihilism and greedy reductionism (he does advocate a form of non-greedy reductionism, which is as it should be). In some cases, a negative reading can only be derived by taking him blatantly out of context. For example, Phillip Johnson:

Dennett cannot be accused of avoiding the religious liberty issue, or of burying it in tactful circumlocutions. He proposes that theistic religion should continue to exist only in "cultural zoos"... those metaphorical cultural zoos may one day be enclosed by real barbed wire...

...I will pass over the legal issues raised by this program of forced religious conversion because the intellectual issues are even more interesting.

This is an outrageous distortion, even for a creationist such as Johnson. This is what Dennett actually had to say:

Safety demands that religions be put in cages, too - when absolutely necessary. We just can't have forced female circumcision, and the second-class status of women in Roman Catholicism and Mormonism, to say nothing of their status in Islam (p.514).

We preach freedom of religion, but only so far. If your religion advocates slavery, or mutilation of women, or infanticide, or puts a price on Salman Rushdie's head because he has insulted it, then your religion has a feature that cannot be respected. It endangers us all... You are free to preserve or create any religious creed you wish, so long as it does not become a public menace (p.516).

In context, Dennett was clearly advocating a crackdown on religions that advocate violence or violation of human rights, not on "theistic religion" in general, as Johnson deceitfully represents him. This is an absolutely correct and ethical position to take, and if Johnson or any other theist opposes it, they are free to come forward and say so.

Though not as narrowly focused on one idea as Dennett's other books, Darwin's Dangerous Idea is no less interesting, and well worth reading. Those who do, regardless of whether they agree with all of Dennett's conclusions, may well find their thoughts opened up along tracks that had not previously occurred to them.

Among Park's targets are the Mississippi inventor Joe Newman, who claims to have discovered a source of infinite free energy; the cold fusion fiasco of Stanley Pons and Martin Fleischmann; Jacques Benveniste and the preposterous claims of homeopathy; and the hysteria stoked by individuals such as Paul Brodeur, who claimed that exposure to the weak microwaves emitted by power lines causes cancer. All of these are obvious targets, and the book skewers each of them skillfully, with clarity and wit. But more surprisingly, in my mind, one of the standout chapters was the one arguing against the manned space program - a position which may seem strange to the probable audience of the book, but for which Park makes a surprisingly strong case. He persuasively argues that manned space exploration, at least so far, is a massive waste of money and unnecessarily risks human lives for no real scientific benefit. Whether readers agree with this position or not, it is definitely an argument worth considering.

The most important thing readers should note about this book is its length. My copy has fewer than seventy pages, and these are tiny pages to boot. The entire book can easily be read from start to finish in under an hour. This is not necessarily a weakness - clarity and succinctness are virtues and this book will not likely be accused of lacking either. However, some potential readers may balk at the cost, especially considering the galling fact that the contents were freely available on the Internet until the book's republication.

In my opinion, the book's major weakness is its rather abrupt ending. Much of its length is occupied by an extended discussion of an anecdote relating to the philosopher Wittgenstein, out of which Frankfurt draws lessons that he uses to define the term bullshit. But there is little discussion beyond that; almost as soon as he finishes his central definition, the book ends. Especially given the opening sentence, "One of the most salient features of our culture is that there is so much bullshit", I was expecting him to provide further examples and show how his definition applies, but he does not do this. This may have been intentional; perhaps his goal was to get readers thinking without alienating any of them by offering examples they may not agree with. Regardless, I feel he could have developed his premise further. Especially considering that this is a republication of an old essay, additional material would have been welcome to justify the cost. Nevertheless, the core concept is an important one, ably defined and categorized by Frankfurt, and deserves to be more widely known and disseminated. What we really need is a sequel that suggests ways to combat bullshit.

The traditional answers to this question have of course come from racist groups, and have centered around the supposed inherent superiority of European people. Diamond firmly debunks this notion, speaking from experience to assert that New Guineans, for example, are at least as clever, adaptable and resilient as Europeans on the average. The true answer to this question, he argues, stems not from differences among groups of humans, but differences in their environments, and ultimately traces back to the very origins of civilization. As it turns out, those areas of the world that contained more useful wild plants and animals that could be domesticated to serve human needs gave their inhabitants a "head start", enabling them to create densely populated agricultural societies before anyone else - and Eurasia, and more specifically the Fertile Crescent of the Middle East, contained more useful species than anywhere else in the world. This initial advantage was increased by the fact that Eurasia, unlike Africa and the Americas, is oriented primarily along an east-west rather than north-south axis, meaning that one can travel across the continent and stay in areas of similar climate relatively easily, allowing domesticated crops and animals to be easily spread.

Once dense agricultural societies did arise, they conferred additional advantages on their people. One was the invention of writing, far more necessary in large, stratified societies to record economic transactions than in small hunter-gatherer groups. Another is what Diamond calls the "lethal gift of livestock": infectious diseases that crossed the species barrier from domesticated animals to human beings. After many waves of plague, Eurasian societies developed partial resistance to these diseases - a resistance that other societies did not have, which was the decisive factor in many contacts between them, leading to the deaths of millions of native people and the complete eradication of many indigenous societies. Finally, there is the development of technology, which occurs most rapidly in dense, stratified societies where not everyone needs to be a food producer, in large areas where there are plenty of potential inventors, and in landmasses lacking significant geographical barriers that would otherwise make it more difficult for new inventions to spread. Eurasia, and more specifically Europe, met all these requirements admirably; and since invention is an autocatalytic process, with the development of new technology stimulating the development of further new technology, even a slight initial advantage could rapidly become exaggerated. Of course, this is exactly what happened. Diamond closes the book with a series of examples drawn from throughout history - in Australia and New Guinea, in China, in Polynesia, in Africa, and in the European meeting with the Americas - to show how the factors he has identified played out in various circumstances.

It is only rarely, when reading a book, do I experience the "click" of facts falling into place - forming a picture which had never occurred to me previously, but which, when the evidence supporting it is lined up, is so convincing as to be impossible to deny. This is such a book. Diamond draws on facts from an impressive number of different disciplines and builds his case with the methodical precision of a true scientist, laying out each of the factors that lead to the success of a particular culture and clearly explaining why each one is relevant. It is a grand and ambitious synthesis that Diamond attempts, but all the evidence suggests that he has succeeded brilliantly.

The book opens with a survey of modern-day Montana - not because it is a society that has collapsed, but because it is one that is currently faced with a series of environmental problems similar to those that brought down societies in the past, and because the individual stories and motivations of its inhabitants can be known, unlike past civilizations that are now extinct. (Diamond also admits to being swayed by the region's natural beauty, which I admit I was unaware of.) He lists some of the environmental problems that threaten Montana, including gold mining that used poisonous cyanide which continues to leak into the groundwater, the logging of forests that destroys ecosystems and detracts from the region's scenic value, soil exhaustion and salinization that makes agriculture impossible, the scarcity of usable water, and the introduction of destructive alien species. He discusses the cultural factors that have led to these problems as well as those that help mitigate or solve them, most notably the conflicts between the region's poor and rich inhabitants.

Diamond then goes on to apply the lessons learned from this example to past civilizations that collapsed, including Easter Island in the Pacific Ocean, the Anasazi in the southwestern United States, the Maya in Central America, and the medieval Norse who settled in Greenland. In each case, he identifies which environmental factors were relevant as well as the poor decisions these societies made that resulted in their downfall. The Easter Islanders, for example, perished because they ravaged their environment, deforesting the entire island to build the giant, enigmatic statues for which they are famous. The Greenland Norse, by contrast, stubbornly persisted in attempting to adapt a European farming and herding society to a frigid climate unsuitable for it, refusing to learn from the native Inuit people who surrounded them. In contrast, Diamond then gives examples of three societies that were faced with environmental disaster but solved their problems and survived - the New Guinea highlands, the tiny Pacific island called Tikopia, and Japan during the Tokugawa shogunate. These examples illustrate that both democratic and autocratic societies can preserve their environments - the crucial factor is not who is in power, but the decisions made by those who have power.

In the final section of the book, Diamond surveys modern societies - those that have collapsed, those that avoided collapse, and those that are threatened with collapse. He discusses, for example, the horrific genocide in Rwanda, arguing surprisingly that its causes were mainly due to population pressure - too many people chasing too few resources - rather than ethnic or religious hatred. He studies the Dominican Republic and Haiti, two nations on the same Caribbean island of which one has virtually collapsed while the other is thriving, and explores the reasons why. He addresses China and Australia, two modern societies suffering from different types of environmental problems, as well as his own home city of Los Angeles. He then provides a list of practical lessons distilled from this analysis relating to the reasons why societies make bad decisions. For example, some failed to anticipate a problem that their actions would cause, such as destruction caused by the introduction of alien species or erosion resulting from deforestation. Others failed to notice a problem that had actually arrived, usually either because the problem was not readily visible or because the ruling elite chose to isolate themselves from their society's problems until it was too late to fix them. Still others failed to take appropriate action to solve a problem, either because of "rational selfishness" (what economists call the tragedy of the commons), or because they held self-destructive values that they refused to abandon even in the face of catastrophe. Finally, Diamond surveys the environmental problems that the world as a whole faces today, and makes the case that although these problems are real and serious, they are not inevitable disasters, and can be averted if we take appropriate action in time.

While it does not lose the methodical, careful scientific tone of Guns, Germs and Steel, I found Collapse to be a more passionately written book, its intent not just to report but also to persuade. Given its subject, that is not surprising. Diamond does an excellent job of outlining the problems that we as a species face today, most notably the desire of billions of people in developing countries to live in unsustainable First World luxury, as well as summarizing arguments commonly offered as reasons not to care about environmental problems and shows why those arguments cannot be sustained. I also greatly appreciated the fact that he suggests ways for concerned citizens to help, such as participating in the efforts of sustainability-oriented resource-management groups like the Forest Stewardship Council. (An environmentalist myself, I was surprised to hear that oil drilling need not be environmentally destructive at all, if done correctly.) Despite its length, Collapse should be required reading for all who are concerned about the planet's well-being. There is no better illustration of why the scientific study of the past is relevant to the present.

Beginning with a brief account of the origin of Earth and of life, the book moves on to provide a historical background to Charles Darwin and his theory of evolution. It then goes on to discuss a variety of behaviors characteristic to living beings - sex, sensory perception, cognition, aggression, dominance hierarchies, mating displays, incest taboos - and provides examples of how these traits and abilities are realized, not just in humans, but in our fellow species from other branches of the tree of life. As in Sagan's other books, the writing is lively and eloquent, bolstered with a profusion of colorful examples and quotations from an astonishing breadth of fields. (My personal favorite is still the moths that will keep throwing themselves mindlessly against glass windows, the species having evolved in a world where there were no invisible transparent objects and thus no need to evolve a behavioral rule to deal with them, or in a similar vein, the caterpillars who will follow scent trails in endless circles. Obviously, humans do not act so mechanically; and yet, the authors ask, are there not circumstances where we, too, keep doing the same stupid thing despite clear evidence that it's not working?)

The last section, however, is where the book truly shines. In it, the reader finds a thorough discussion of our very closest relatives, chronicling the marvelously complex lives of apes, especially chimpanzees - their sexuality, their genetic similarity to us, their social relationships with each other, their ability to use tools and language, even their culture. A clever chapter titled "Gangland" imagines chimpanzee social life from a chimp's perspective to show just how recognizable it is. The more we learn about our relatives, Sagan and Druyan write, the more we find that animals in general and apes in particular are in some ways very like us - indeed, one chapter is devoted entirely to listing traits claimed by various scientists and philosophers to be exclusive to humanity, and then demonstrating that other species possess them. The differences between human beings and other animals, the authors assert, may merely be differences of degree, not of kind.

The epilogue mentions a forthcoming sequel, one focusing on the origins of human civilization as this one focuses on the origins of human nature. That sequel, as far as I know, was never written, presumably because of the illness which tragically ended Carl Sagan's life early. Still, this sorrowful reminder does not detract from an illuminating look into our kinship among the animals, one that does much to dethrone the ancient pretension, born of religious belief, that humanity is the unique pinnacle of creation. As with all of Sagan's books, it is a glimpse into a mind whose time among us was cut far too short.

Superstring theory holds that the most fundamental components of matter are not, as was previously thought, pointlike particles, but instead tiny vibrating loops called strings. Just as a violin string can play different musical notes by vibrating at different frequencies, so too do the different vibrational patterns of these strings give rise to all the particles of matter and energy physicists are familiar with. But string theory has other, more bizarre implications, such as that the four dimensions we are all familiar with - three of space and one of time - are not all that exist. Instead, our universe may have as many as eleven dimensions, the extra seven being "curled up" in such a way that we do not notice them. Greene discusses this concept and its implications at great length, and then mentions the so far even more mysterious "M-theory", which suggests that strings themselves may have multiple dimensions.

Potential readers should be warned that this book can get very technical. Greene does an admirable job describing the counterintuitive consequences of relativity and quantum theory, but when it comes to the even more esoteric points of string theory - particularly the six-dimensional figures called Calabi-Yau shapes, which have to do with the extra dimensions the theory proposes and which Greene himself worked on - the prose becomes dense. To a degree this is to be expected, since there is only so much that can be done with metaphors to explain aspects of physics that lie so far beyond everyday experience, but readers wary of such complex details may want to be steered away. On the other hand, for those who have the patience and the interest, The Elegant Universe is an illuminating look at the very cutting edge of scientific thinking on some of the most fundamental questions of the cosmos. String theory may or may not be correct, it is still too soon to tell (and I, admittedly, am not qualified to decide); but Greene is a passionate advocate, and his case is strongly made.

In the first two sections of the book, Greene considers how traditional notions of space and time hold up in the light of the two theories that form the pillars of modern physics, general relativity and quantum mechanics. Though Newtonian mechanics asserted that space and time were absolute, Greene demonstrates that such easy and satisfying beliefs can no longer be sustained. Einstein's theory of relativity, for example, tells us that observers in relative motion will not agree on measurements of distance or time, while quantum mechanics has sundered ordinary notions of cause and effect through effects such as entanglement, in which apparently independent particles are shown to be correlated in some mysterious way such that a change to one immediately produces a corresponding change in the other, regardless of the distance between them. Ordinary intuitions of time suffer equally persuasive blows, as Greene shows that the concept called now, one moment distinct from all other moments, does not hold up. Again, according to Einstein's theories, observers in relative motion will not agree on what events are occurring in the present, and Greene explains how this leads to the conclusion that all events throughout history, in a certain sense, exist simultaneously. There is nothing fundamental that labels an event as belonging to past, present or future, which suggests that the flow of time as we perceive it is an illusion. Perhaps most "spooky" of all, Greene details experiments in quantum mechanics that suggest that, in a way, the future can influence the past. Reading these chapters convinced me, as I think it must convince any fair-minded reader, that the universe is a far stranger and yet more mysterious and wonderful place than we can imagine.

The third section of the book, in my opinion the best, deals with cosmology, the origin of the universe and of space and time. In a set of brilliantly lucid explanations, Greene discusses the shape of space, the reason why particles have mass, the cause of the Big Bang, the reason why the early universe had such low entropy, and even the origin of the matter and energy of the Big Bang itself. Most of these issues center around two hypotheses in cosmological physics: the so-called Higgs field that fills all of space, and the theory of inflationary cosmology that extends the basic model of the Big Bang. This is the first science book I have read that clearly explains these things, and Greene does so in an admirably succinct, clear and compelling way. The fourth section, which discusses string theory, is essentially a summary of The Elegant Universe and will be familiar to readers of that book, although there is also some interesting new material on the related "braneworld" models of cosmology, such as the recently proposed ekpyrotic universe theory.

The Fabric of the Cosmos is an extraordinary insight into questions on the frontier of science. Greene explains complex issues in a clear and highly readable way; one feature of the book for which I particularly applaud him is the chapter explaining how some of the ideas he presents can be and currently are being tested by experiment. This is a crucial part of science all too frequently overlooked. Furthermore, though religion was never explicitly mentioned in this book, as it was not in the last book, I am confident that Greene is an atheist. It was gratifying to see the origin of the universe discussed in a refreshingly straightforward and scientific manner, without the lip service paid to a creator-deity that seems to be obligatory in so many works that touch on this topic. There was even one section in which he uses a picture to represent all of space throughout all of time (the "spacetime loaf", in the book's terminology) and then points out that the perspective shown in the figure, an "outside" perspective looking "in" on spacetime, is a fictitious vantage point that no one actually has. In a later chapter where he discusses the prospect of using quantum teleportation to transfer a living being from one location to another, he states a belief that the basis of the mind is entirely physical. The one aspect of the book that irked me to any degree was his constant use of characters from TV shows (especially The Simpsons) in his analogies; at times this starts to drag and becomes overly cutesy. Even so, the reasoning is persuasive and the points are clearly made. With this book, Brian Greene has shown that he deserves a place among the true popularizers of science, and I intend that as a high compliment.

Zimmer begins with a historical perspective: the nineteenth-century discovery of lungfishes such as Lepidosiren paradoxa that evaded easy classification and gave one of the first boosts of support to the then-novel theory of evolution. Over time, new fossils were discovered that further extended this line of evidence, including lobe-finned fishes from the ancient Devonian period that bore tantalizing similarities to land vertebrates. After a frustrating paleontological drought, new discoveries finally surfaced in the late twentieth century, and what had been a trickle became a flood of new fossils that showed in detail how vertebrates left the water. According to Zimmer, the old idea that tetrapods evolved from primitive lungfish-like creatures that could slither from puddle to puddle in a dried-out desert landscape has now been disproven; instead, the evidence shows, legs first evolved underwater, for sculling along the bottom of the murky, tangled swamps and coastal lagoons of the Devonian period, and were coopted for walking on land only secondarily. Related to this topic, Zimmer discusses how a hand could have evolved from a fin through the action of the crucial "homeobox" genes that control embryonic development, and also details the evolution of lungs, again before fish left the water, as an adaptation for swimming more efficiently.

The book then moves on to the evolution of cetaceans - whales and dolphins - and again begins with a historical perspective, the discovery of an extinct whale ancestor named Basilosaurus. Again, after a drought of several decades, new discoveries arose in the twentieth century: this time in modern-day Pakistan, along the shores of an ancient sea called the Tethys, of which today's Mediterranean is a shrunken remnant, that once stretched from Gibraltar to India. It was here that mammals returned to the water, as Zimmer documents with the discovery of fossils like the astonishing Ambulocetus, a proto-whale that resembled a furry crocodile. He also capably summarizes research into the physics of swimming and the ongoing scientific debate over exactly which branch of early mammals whales are descended from - a lineage of primitive carnivores called mesonychids or the hoofed mammals called artiodactyls (a debate that now seems to have been resolved in artiodactyls' favor by new fossil evidence). Finally, he discusses the origin of more recent cetacean adaptations such as the baleen of baleen whales and the famous intelligence of dolphins. A persuasive antidote to the creationists who claim that there are no transitional fossils, At the Water's Edge is also a well-written and intellectually stimulating account of the glorious workings of evolution both in our own ancestry and in our most iconic relatives among the mammals.

But first he argues that, regardless of its implications, evolutionary theory is the accepted scientific consensus for a good reason, namely that it finds overwhelming support in the facts. In three chapters, Miller skillfully dismantles the central arguments of three major types of creationists. Chapter 3, "God the Charlatan", refutes ultra-fundamentalist young-earth creationists such as Henry Morris, explaining how radioactive decay shows beyond a reasonable doubt that the Earth is indeed billions of years old. Miller rightfully scorns their assertions that the universe was created with an "appearance of age", pointing out how this requires belief in a deceptive deity who created the world with false evidence of a history it never had. Chapter 4, "God the Magician", targets old-earth creationists such as Phillip Johnson, taking them to task for their misrepresentations of Gould and Eldredge's punctuated equilibrium and showing that, contrary to their claims, the geologic record contains a significant number of clearly transitional fossil series. Finally, chapter 5, "God the Mechanic", delves into the claims of intelligent-design advocates such as Michael Behe, showing that evolution is easily able to produce the types of complex molecular machines, such as bacterial flagella and the blood clotting cascade, that they claim to be "irreducibly complex". Miller's experience in debating creationists shows, and each chapter is supported by well-chosen examples from evolution's vast array of evidence.

Miller then considers the question of why it is that creationists feel so threatened by evolution in the first place, and I must agree with the answer he suggests: because there are prominent scientists who have said, in public, that evolution is a compelling argument against the existence of a personal God, an absolute purpose in life, or objective principles of morality. It is no wonder that many deeply religious people have reacted strongly against those who have framed the clash between science and religion in such uncompromising terms. And though I am an atheist myself, I must agree with one of Miller's central arguments: merely because evolution was the process that brought the human species into existence, it does not follow that God had nothing to do with it. (I do, of course, believe that there are good reasons to consider atheism true; I simply do not believe that evolution is one of them.) The scientists who say that evolution implies atheism, though I respect and admire many of them, are wrong to say so, and have not been sufficiently careful to keep their personal opinions separate from their scientific work.

The problem, as Miller deftly points out, is that many Christians have claimed that if Genesis is not literally true, then the entire Bible is worthless - and some atheists have been only too glad to take them up on that proposition. Though this does not absolve these scientists of responsibility, it is in the main correct to say that the creationists' problem is largely of their own making. Miller, on the other hand, rejects this god-of-the-gaps view and states his belief that God works through natural processes, rather than outside them. In this way, according to him, the intricacy of evolution is a far more glorious tribute to the wisdom and subtlety of the creator than the six-day story derived from a naively literal reading of Genesis. The Bible, in his view, was meant by its Author to teach spiritual and moral rather than scientific truths.

Of course, I do not agree with Kenneth Miller's religious beliefs. However, he has every right to hold them, and I respect his honesty and sincerity. And he is absolutely correct that the injudicious and overzealous proclamations of some atheist scientists have done more harm than good. That is not to say that there would be no creationists if not for the likes of Richard Dawkins - there will always be those who cannot abide anything but a blind literalism when it comes to religion - but they have, perhaps, exacerbated the problem. Finding Darwin's God is not just an excellent science book, but a valuable reminder that the defenders of evolution are not dogmatic and are not all atheists.

The opening chapter deals humorously with the origin of the phrase "billions and billions", which is like many other famous pop-culture phrases in that it was never actually spoken by the person it is usually attributed to ("Elementary, my dear Watson", "Beam me up, Scotty" and "Play it again, Sam" being other notable examples), and how Sagan came to terms with being associated with it. From there, he segues into other topics related to quantification, including the magnitude of large numbers and the power of exponential growth, both of which he ties into subjects that should concern us, such as human population growth. There are several miscellaneous science essays, as well as a light-hearted musing on our society's obsession with sports and how it may date back to hunter-gatherer times (the names of tribes among the !Kung Bushmen, Sagan shows, are remarkably similar to the names of professional American sports teams).

The second section of the book, concerning the fragility of our planetary home and the need to protect it, opens with a chapter titled "The World That Came in the Mail", a brilliant parable about Sagan's own experience tending to a tiny self-contained aquatic ecosystem. He points out that even some very simple organisms, a colony of tiny shrimp and algae, excel at at something we humans have not yet learned: how to live sustainably, without destroying our own home in the process of existing. Though the environmental dangers that we face are legion, Sagan concentrates on two major problems, ozone depletion and global warming, of which the former is, thankfully, mostly solved and the latter is still pressing. He addresses the balance between safety and prudence and the encouraging signs of a developing alliance between science and religion to protect the planet.

The third section of the book deals with politics. It includes an essay, published in both American and Soviet magazines (at the time of its writing, the USSR still existed and nuclear war was a very real possibility) urging the world's two superpowers to unite against the common problems of humanity; and it shows what changes Soviet censors made in the essay before distributing it to their people, a characteristic reminder of how the worst aspects of humanity continue to interfere with the best ones. Other essays discuss abortion and his attempts to find a reasoned, moderate stance on the issue (and show how surprisingly recent a phenomenon the religious opposition to it is), morality and the prisoner's dilemma, and a speech, given on the 125th anniversary of the Battle of Gettysburg, to illustrate how our destructive capabilities have grown since that conflict and to urge disarmament, pointing out how much good could be accomplished by diverting just a small fraction of the money still being spent on national defense.

The conclusion of the book, an essay titled "In the Valley of the Shadow", is something more personal: the heart-wrenching account of Carl Sagan's death, begun by him and completed by his wife Ann Druyan. Sagan writes, with simple candor and understated courage, of his out-of-the-blue diagnosis of myelodysplasia, a rare and deadly form of leukemia, and how it brought him to confront in the most jarringly unexpected way the possibility of his own death. Through round after grueling round of medical treatments, Sagan fought the cancer and apparently defeated it - only to succumb, at the last, to pneumonia brought on by the immune suppression necessary for a bone marrow transplant. His own listing of the things he would regret not living to see, saddened but not fearful, along with Ann Druyan's account of his final hours, have brought me to tears on more than one occasion and underscore how bitter this loss was and how greatly humanity was diminished thereby. When my time comes, I hope only to face it with even half of Sagan's courage and good grace.

Wilson begins with a personal account from a South American rainforest in the country of Suriname, a place whose beauty still haunts him. An entomologist by training, he writes of the astonishing intricacy and diversity of life in even a single scoop of soil, the small species that humans so often overlook and yet that are so vital to the health of an ecosystem. The colonies of tropical leafcutter ants, which act as "superorganisms" composed of thousands of individuals serving the interests of the group, are described in affectionate detail. From this starting point, Wilson then casts his gaze to broader subjects, discussing science as a poetic enterprise - the human search for elegance and beauty in the laws of nature. In a particularly memorable chapter, he introduces an imaginary time machine that allows us to perceive the four vastly different time scales related to life - biochemical, organismal, ecological and evolutionary - and shows what can be gained from a perspective broadened in this way. He delves into human psychology with the potent image of the serpent, a recurring cultural symbol that we both fear and venerate, supplanted by another personal story of Wilson's own boyhood encounter with a poisonous water moccasin in the swamps of Florida. He also surveys the type of landscapes we are inclined to find beautiful, speculating on connections to our evolutionary past and implications for future exploration.

Finally, in what is in my opinion the best essay in the book, Wilson discusses the idea of a conservation ethic: a moral imperative to preserve the maximum possible number of species and the most biodiversity, which are things that once destroyed can never be replaced. Such a policy can be supported for even purely selfish reasons, Wilson argues, listing a stunning variety of species that either may potentially benefit humankind or that already have done so - better agricultural yields, novel pharmaceutical compounds, better fuels, fibers, fertilizers, antibiotics and more - and shows just how chillingly close many came to extinction from our relentless destruction of the natural world before their properties were discovered. We must develop a stronger conservation ethic, Wilson urges, and argues that we will as our ethics inevitably expands along with our knowledge. The only question is how much more will be lost before that comes to pass.

Sagan begins the book with several chapters exploring what he aptly calls the "Great Demotions": the beliefs in our species' centrality, in our supreme importance to the grand scheme of things, that have crumbled one by one with the rise of the scientific outlook. The belief that the Earth was at the center of the universe, that the planets and stars revolved around it, that it was the only world of its kind in the cosmos, that everything was created specially for our benefit - these conceits and others have fallen, though not without fierce resistance from those who did not wish to see humanity's obvious importance challenged. (Sagan recounts briefly how Galileo was forced to recant under threat of torture for his defense of heliocentrism.) In reality, as Sagan capably demonstrates, there is no scientific reason to believe that our existence was preordained or that we were brought into being for a higher purpose; however, there is true awe and wonder to be found in genuine understanding, and our hard-won realization of how truly vast and majestic our cosmos is.

In a lead-in to the next section, Sagan takes up the question of whether an alien observer could deduce the existence of intelligent life on Earth from afar. As he shows, that the Earth is a life-bearing planet could be detected from a great distance; but only a very close look indeed would reveal the presence of humanity. For all our self-congratulation, the work we have done in reshaping the planet's surface is effectively invisible from more than a few tens of kilometers up.

Sagan next takes up the topic of humanity's own, so far tentative explorations of other worlds, both those we have already carried out and those we may undertake in the future. He discusses the enormously fruitful Voyager missions to the outer solar system; the Cassini/Huygens mission to Saturn's moon Titan (which had not yet happened at the time of this book's writing); our present and potential future exploration of Mars and Venus, our nearest planetary neighbors; and the manned missions to low-Earth orbit and to the Moon. He does not overlook the irony of the fact that these missions, originally undertaken as a matter of national bragging rights and political one-upsmanship, have furnished our species with a powerful, transcendent vision of our shared humanity and the fragility of the blue world we call home. Finally, Sagan looks toward the future with explorations of more speculative topics: the hazard of asteroid impact and how to avoid it, the possibility of terraforming other worlds to make them congenial to human habitation, the SETI program and the implications of alien life, and the remote future when we ourselves may begin the colonization of space - assuming, of course, that by then we have the wisdom and the will. Sagan argues compellingly that our destiny lies among the stars, and that even if that destiny is only for the far-distant future, that does not reduce our present responsibility to care for and to cherish this pale blue dot we call home.

After documenting this network, Krakauer delves into Mormon history, writing in detail about how the church originated with Joseph Smith and his dubious revelations, and chronicles its growth, its often violent clashes with the authorities and with its neighbors, and its institutionalization of polygamy which originated with Smith himself. The book admirably casts doubt on the self-serving nature of Smith's supposed revelations, and makes clear that he was not above blatantly exploiting others' belief in him for his own personal advantage, especially when it came to taking "plural wives" (on at least one instance he told a girl that she would be damned to eternal torment without hope of escape unless she agreed to marry him). Though Smith was murdered in 1844 by a vigilante mob, the church he created lives on, and Krakauer's account is a must-read for a nonbeliever's perspective on its rise.

In her magnificent Freethinkers, Susan Jacoby sets the record straight. Drawing a broad sweep through America's history, she shows that while hostile religionists have always been a major force in American politics, this country also has a long and proud tradition of religious dissent and freethought that dates back to even before the Revolutionary War. In a series of wide-ranging chapters, she discusses, among other things, the secularism of revolutionary founders such as Thomas Jefferson and James Madison; the tireless crusade of Thomas Paine, who fought fearlessly against tyranny of every kind and was rewarded with the scorn and hostility of his countrymen for attacking religion; the religious skepticism of Abraham Lincoln; and the life of the Great Agnostic, Robert Green Ingersoll, the most important and influential American that most modern Americans have never heard of. A dedicated foe of slavery, religious oppression, and cruelty of every kind, Ingersoll was chiefly responsible for inaugurating the late nineteenth-century "golden age of freethought", a time when lecturers and orators could travel the country delivering rousing anti-religious speeches to packed lecture halls in every town they visited. Jacoby also surveys the intimate role that freethought played in the abolitionist, feminist, women's suffrage and civil rights movements, whose leaders were frequently and sometimes accurately demonized as atheists by the fundamentalists of the day. While not all the historical figures she discusses were atheists, all shared a belief in the essential goodness and decency of humanity, in the virtue of doubt and skepticism, and in the necessity of drawing moral lessons from human needs and values rather than religious authority.

In the later sections of the book, Jacoby studies the resurgence of fundamentalism at the dawn of the twentieth-century "culture wars", considering the issues of mail censorship, civil rights, antievolutionism, the Scopes trial, birth control, red scares and anti-communist hysteria, and the current religious assaults on science and reproductive freedom. She concludes that although the freethought movement today is weaker than it has historically been, it is within our power to change that - but to do so, we must reclaim the language of the Enlightenment that people like Ingersoll and Paine wielded so well, and proclaim with reason and passion the positive values we stand for.

Since becoming an atheist, I have found that there is a distinct shortage of books that specifically defend atheism in a comprehensive and accessible way. In this respect, Losing Faith in Faith is - and I use this word with the deepest possible irony - a godsend. Barker's story of his own deconversion is deeply personal, sincere and plainly written from the heart, and even when unrelentingly criticizing those aspects of religion that most deserve to be criticized, he does so in a civil and courteous manner. This book poses a powerful challenge to believers and equips skeptics of theism with a set of compelling arguments, and as such, has my highest recommendation for anyone who has ever clashed with Christian proselytizers. But even beyond my personal opinion of its merits, there is another fact about it that bears mention: several devout Christians of my acquaintance, after being informed what the book was about, refused to read it. I believe that to be the best endorsement possible.

Doherty's case is drawn from a broad survey of ancient literature both inside and outside the canon of the Bible. To begin, he rightly points out that early Christianity was not the unified, lockstep movement some modern apologists think it was. Rather, it was a riotously diverse movement, a tapestry of many different, often incompatible threads of belief and tradition. Out of all these, he identifies two major categories, which he dubs the "Jerusalem Tradition" and the "Galilean Tradition". The first section of the book deals with the first of these, which consists mainly of Paul and the other epistle authors. Doherty points out that the Christ of these letters is a divine spirit, a heavenly, spiritual figure; and yet this cosmic force is never quite identified with a recent human being. Instead, the epistles focus almost exclusively on his sacrificial death and resurrection, and include only the barest minimum of biographical details predetermined by Old Testament prophecy. Doherty effectively shows how the epistle authors fail to appeal to teachings or events from the life of Jesus even when circumstances cry out for such a mention, and more, describe the actions of Christ in exclusionary terms that rule out any human career - silences best explained by postulating that they knew of no such thing. Doherty illuminates the origins of this tradition by comparisons to the Greek philosophical idea of the Logos and the beliefs of the pagan mystery cults, showing how the Jerusalem Tradition was cut from the same cloth as the other upstart religious and philosophical sects of its day.

Doherty then takes up the Galilean Tradition, discussing early Christian documents - the Gospel of Thomas, the hypothetical collection called Q that underlies the Synoptic gospels - and showing that they lack knowledge of a crucified Jesus. Instead, they bear resemblance to another philosophical tradition of the time, that of the Cynic movement. The gospels' passion account, by contrast, shows signs of having been produced from the Old Testament via a Jewish process of scriptural interpretation called midrash. Arguing from the primacy of Mark, Doherty theorizes how and why the gospels were first written, and then shows how these two traditions gradually became intertwined to create a "composite" Christianity. To further bolster his case, he illuminates the lack of mentions of Jesus among Roman historians and the gradually dawning belief, among Christians, in a historical founder. He also provides some startling quotes from second-century Christian apologists to show that belief in a historical Jesus was not necessarily part of early Christianity. Broad in its sweep and revolutionary in its conclusions, The Jesus Puzzle makes a compelling argument (and was persuasive to the writer of this review). It deploys an impressive array of converging lines of evidence in its support, and accounts for the anomalies and inconsistencies in early Christian expression in a way that the orthodox interpretation does not. Despite the prevailing biases in theological circles that have so far kept its central thesis from being seriously addressed, this is a book that deserves, at the very least, to be read widely and given a fair hearing. (For interested readers, "Choking on the Camel" provides an introduction to Doherty's argument.)

Doherty's book closely follows the format of Strobel's, a series of interviews each of which is intended to establish one point in a progression up to acceptance of Christianity. Since Strobel has styled his book a "case" and encourages his readers to think of themselves as jurors, Doherty extends the metaphor, quoting Strobel and his handpicked experts as if they were witnesses in a courtroom and he the opposing attorney. While this literary device does not by itself strengthen Doherty's arguments, it does make the book more colorful and interesting to read, and I appreciated the way it provided a sense of balance to the endeavor. After all, though Strobel encourages his readers to picture themselves as jurors in a trial, he himself presents only one side! A verdict in a case can hardly be reached before both sides have had their say.

Strobel's interviewees are undeniably highly qualified in their respective fields. But all the credentials in the world cannot firm up a fallacious argument, and Doherty deals with each of them with skill and poise, pointing out the leading and one-sided nature of Strobel's questions, and making brilliantly clear just what evidence each of them is misinterpreting or glossing over. Though full summaries will be omitted for the sake of space, several rebuttals are particularly noteworthy. One is when, in response to Strobel's question regarding whether there is reason to believe that the gospels were written by the men whose names are now attached to them, Craig Blomberg claims that that matter was "just not in dispute". In response, Doherty points out that there are no surviving records of anyone in the Christian community even making reference to the gospels before the second century, rendering Blomberg's claim a fallacious argument from silence. The first commentator to list the gospels by name and cite them as authoritative (Irenaeus of Lyons) is not until 180 CE, over a century and a half after when the gospels are usually thought to have been written. Another is when Blomberg claims that the gospels should be considered trustworthy because their authors did not omit potentially difficult or embarrassing material - but as Doherty points out, the Gospel of John does exactly this in scenes such as Jesus' baptism or the Garden of Gethsemane. Finally, an even more devastating rebuttal comes later in the book when Doherty catches William Lane Craig in an outrageous and blatantly circular argument regarding the historicity of the guards at Jesus' tomb: Craig literally quotes the Gospel of Matthew in support of itself!

Although Doherty's mythicist theory of Christian origins is not advocated here as strongly as it is in The Jesus Puzzle, it is present, though it would be fair to say that his rebuttal does not depend on it. When combined with The Case for Christ, these two books present an engaging and fairly complete picture of the state of Christian apologetics, both for and against. Doherty's case, though, is by far the stronger.

The first section of the book deals with the formative events of the Israelite nation, as chronicled in scripture - the wanderings of Abraham, Isaac and Jacob, the captivity and subsequent exodus from Egypt, and Joshua's conquest of Canaan. As Finkelstein and Silberman write, these tales can now be seen to be, not historical records, but elaborate allegories, written to address issues relevant to the kingdom of Judah at the time of the Bible's composition through the lens of a heroic mythological past. Archaeological evidence verifying the literal occurrence of these events is nonexistent; many of the sites mentioned in the narratives did not exist at the time these events purportedly took place. What is more, from what we know of the ancient world, there is no period into which these events could be fit without contradiction or anachronism.

The book then moves on to address the true origin and history of the Israelites, which, the authors argue, can first be identified in a wave of settlement that occurred in the highlands of Canaan around 1200 BCE. These villages were a simple and apparently peaceful subsistence culture, apparently originating from nomads who settled down to a sedentary life. ("Irony of ironies," the authors write, the Israelites were themselves originally Canaanites!) And where the Bible depicts a once-mighty unified monarchy splitting into two separate states, the evidence shows that the northern kingdom of Israel and the southern kingdom of Judah were separate from the beginning. While Finkelstein and Silberman do not question the existence of David and Solomon, they conclude that the Bible's description of their empire has been greatly exaggerated, and that it was at best a small rural kingdom. Israel was always the richer and more prosperous of the two - until it was destroyed by the mighty Assyrian empire in the eighth century BCE. This event would have dramatic consequences for marginal Judah and ultimately for the modern world, leading indirectly to the emergence of Yahweh-only monotheism, a disastrous war with Assyria, Judah's destruction and exile at the hands of the Babylonians, and finally to the origin of the Bible as we know it.

While The Bible Unearthed is not a technical book, it is not always easy going either. Familiarity with the events of the Old Testament is a definite prerequisite, as is an interest in the past and in archaeology. ("Let the Stones Speak" provides an introduction to the material it contains, for interested readers.) That said, there are some places where I almost felt it was not technical enough. Some of the conclusions it draws are sweeping, and while supporting evidence is not omitted, more detail would have been welcome. Of course, there are good reasons why the full range of detail cannot always be provided: many of these conclusions are founded on an enormous variety of data, and this book was not intended to be a comprehensive encyclopedia of Ancient Near East fieldwork. TBU is more of a summary of archaeological discoveries over the past several decades than a thorough enumeration of the finds that led archaeologists to this point. However, it more than adequately serves as a beginning point to this complex and important field of science.

Although Discworld began as a straightforward satire of traditional fantasy, Pratchett soon found his own voice as a writer, one that blends an optimistic humanism with a deft comedic touch, and this book clearly demonstrates this evolving sensibility. It does not exactly advocate atheism, which would be rather difficult in a fantasy world where gods actually exist (and take considerable displeasure at being blasphemed), but it does promote a commendable view of morality which holds that human lives and human needs must always come first. This is no small feat in a satire, but Pratchett knows exactly when to be light and when to be serious, and there were some scenes that I found outright haunting (the encounter in the desert with the ghost of a long-dead god comes to mind). For a thoughtful escape, Discworld in general and Small Gods in particular are well worth it.

If one can adapt to the author's stylistic quirks and assimilate the occasionally dizzying complexity, Snow Crash is a fast-paced and highly recommended read. Stephenson extrapolates a glitteringly fractured future world that seems to lie just around the corner from our own, and capably mixes futuristic technology with ancient mythology to build a strikingly plausible picture. More, his explanation of the origin of the biblical deuteronomists and the seductive allure of the rival cult of Asherah is among the most amusingly reasonable I have read. (One of my favorite lines from the book was when one character asks if Snow Crash is "a virus, a drug or a religion," only to be met with an unconcerned "What's the difference?") For an intellectually challenging work of sci-fi, look no further.

As he comes of age in Roman-ruled Palestine, Jesus of Nazareth (or, as the book calls him, Joshua) is aware that he is the messiah, and that he possesses miraculous powers. But he does not know what his mission on earth is or what his gospel should be, and his prayers to God for enlightenment go unanswered. Desperate, he sets out on a quest to find the only people who knew of his godhood before he himself did - the three wise men, Gaspar, Balthasar and Melchior - in the hopes that they may be able to provide him with answers, with his faithful, albeit irreverent, childhood friend Biff his only companion. Josh and Biff's quest takes them from Judea to the mountains of Afghanistan, where the magician Balthasar teaches them about chi, alchemy, and the finer points of demon-summoning; to the icy monasteries of the Himalayas, where the abbot Gaspar tutors them in Zen meditation, kung fu and yak-shaving; to the muddy banks of the Ganges, where they learn the Kama Sutra and the principles of Hinduism from the ascetic Melchior, and incidentally find the time for an encounter with the murderous followers of the fearful death god Shiva. At the conclusion of all these wanderings, Josh and Biff finally set out for home, anxious for a reunion with their childhood friend Maggie of Magdala; but things have taken a downturn in their absence, and the Jewish temple elders, to say nothing of the Romans, are none too happy about Josh's spreading his new gospel or his ragtag band of disciples. If you've read the Bible, you may think you know how this all turns out - but, well, Biff has a few things to say about that as well...