137 of 140 people found the following review helpful
on June 24, 2006
Hazen's book "Gen-e-sis" is much like Ward's new one, "Life as We do Not Know It," which I read at the same time. In fact, the two authors are so similar in their interests and goals I was surprised that neither mentioned the other by name. Hazen's style is more direct, while Ward's is a little more playful. While Ward's emphasis is definitely the search for extraterrestrial life and discusses planetary potentials, Hazen's has a greater focus on what it took to have developed it here in the first place and discusses the details of origin research.
"Gen-e-sis" is a good source for the who, what, when, where, why and how of origin science. It is an up to date compendium of what is known about modern microscopic life and the systems that it uses. More importantly for the student interested in the topic, he provides a very good description of the equipment, techniques, and personal characteristics of the researchers doing this type of work. The book would be a very good addition to a high school library, not only in its capacity as a reference on origin of life research, but for the information on the occupation of bioscience researcher.
The author approaches his topic by examining the issues of how life arose from non-life and which of several issues was solved first: cellular segregation of "outside" from "inside," metabolism, or replication. These points are not necessarily clear to most of us. We are ourselves and live with other organisms of great complexity, not only with respect to internal organization but with respect to inter-species organization in the natural ecology of our environment. In short life on the planet has become so elaborate that it almost seems impossible that it could ever have been simpler even at the level of single cells.
Dr. Hazen explores the current research into the ubiquity of biomolecules, how they might arise spontaneously, how they survive under different conditions, and how they might congregate into larger molecules. I found especially interesting the discussion of the spontaneous self-aggregation of lipid membranes from molecules with hydrophilic and hydrophobic ends. Certainly the formation of double layers of these molecules into more cellular like membranes in laboratory settings was amazing.
He also discusses the RNA and DNA `worlds' and the possibility that protein or other catalytic molecules might have performed the function of replicators and metabolizers until the more complex systems used by modern life arose to take over the functions. He discusses the now rather old notion of a clay world, proposed originally by Cairns-Smith. Here clays of various types are believed to have served as templates for the natural aggregation of organic molecules which later became independent of their clay "parents" by replicating themselves. This theory still has an undeniable fascination. The possibility that rock pores might have served as the original cell "membranes" is also intriguing along this line.
With a passing reference to the work of the Santa Fe Institute, particularly the research of Kaufmann, and of Per Bak into self organizing criticality and self emerging properties, Hazen notes that critical quantities of materials needed for life to get going may have led almost spontaneously to the origin of life. In fact it is suggested that it might do so where ever these conditions arose in the universe.
Probably one of the best features of the book is the discussion of the problems that arise when carrying theory into research. A great theory may produce disappointing research results, may not be practicable at all, or may illuminate problems with the theory. A case in point is the issues arising with the self organizing membranes mentioned above. Here it was discovered that while membranes could arise quite simply, they didn't allow anything to pass into or out of the interior. Living cells allow a flow of materials across the membrane, usually with a gradient of some kind, prevent materials from entering or leaving by virtue of pore verses particle size, or actively transport materials into or out of the cell's interior. A cell that can't do this would either poison itself or starve to death. Such research provides useful negative information to take back to the drawing board.
An excellent overview of origin science, and a good book to read with Ward's on extraterrestrial life.
102 of 103 people found the following review helpful
on October 26, 2006
Life on Earth appeared nearly 4 billion years ago, an emergent consequence of properties and processes enabled by chemistry and physics - bursting forth from air, water, rock and the thermodynamics of nonequilibrium systems. The origins of life pose a mystery as deep as any question facing contemporary science. Intrepid researchers are taking increasingly bold steps in an ultimate adventure to understand how prebiotic chemical systems self-organized and crossed the threshold separating life from non-life on our barren young planet. Abiogenesis, the scientific quest for life's origin, is profoundly moving and brilliantly presented in this superb book.
Author Robert Hazen exemplifies the intellect, insight, determination, and sense of adventure that scientists around the world utilize when seeking answers to life's most basic riddles. As a researcher in the Geophysical Laboratory at the Carnegie Institution in Washington, D.C., and the Clarence Robinson Professor of Earth History at George Mason University, Hazen has spent many years researching the fundamental mechanisms nature utilized to realize life's genesis. His impressive laboratory research has choreographed the spellbinding sequence of events that synthesized many of the essential carbon-based macromolecules that acted as the components and scaffolding from which life emerged.
By subjecting simple and abundant chemicals to the high temperatures and crushing pressures encountered near deep ocean vents, Hazen hypothesis that life may well have begun in such an environment - facilitated and nourished by a teeming mixture of catalytic minerals and organic compounds energized by abundant geotectonic forces. Other scientists believe that life originated on Earth's surface where ocean waves repeatedly lapped vesicle laden rocky shorelines as solar energy and evaporation organized and sequestered prebiotic building blocks. Given our current state of knowledge theories abound, but Hazen is a perspicacious guide who illuminates all of the pathways scientists have proposed as tentative first steps towards life.
"Genesis: The Scientific Quest for Life's Origins" moves beyond the laboratory and into the field to meet key players, witness the debates, and participate in the discoveries and disappointments that are leading inexorably to a plausible explanation for the momentous beginning of life. Theories of emergence and complexity are poised to answer a multitude of issues - even as they raise the possibility that natural processes exist beyond what we now know, or even imagine. Genesis tells the tale of a transforming scientific adventure in our search for life's origins. This is a profound and numinous book aimed directly at the heart of who we are and how we came to be - it has my highest recommendation. Buy two copies, one for yourself, the second for a friend.
Iris Fry's The Emergence of Life on Earth: A Historical and Scientific Overview is also excellent, and Life on a Young Planet: The First Three Billion Years of Evolution on Earth (Princeton Science Library) by Andrew H. Knoll both compliment this book. Singularities: Landmarks on the Pathways of Life,Vital Dust: Life as a Cosmic Imperative, and Life Evolving: Molecules, Mind and Meaning by Christian de Duve are superb and insightful. Finally What is Life?: With Mind and Matter and Autobiographical Sketches (Canto) by Erwin Schrodinger and the Origin of Life (Dover Phoenix Editions) by A. I. Oparin are classics in the field.
44 of 46 people found the following review helpful
on November 28, 2005
This book is a fine overview of the scientific “origins” puzzle. It is not a biology book, but a book about how biology might come to be. Hazen provides a theoretical framework and covers the emergence of organic molecules, biological polymers and replicating systems while telling the friendly, personal stories of his own research. Hazen does a good job of presenting the facts while making it clear that there is much that is speculative about the field. An excellent book for most of us who are not familiar with the science; well-referenced enough, including references to primary scientific journals, to provide a gateway for those who want to learn more. Not intended for those who know a lot about the issues already, and perhaps a little too chatty for my personal taste, but an easy and enjoyable read.
34 of 35 people found the following review helpful
on June 12, 2006
This book, by scientist Dr. Robert Hazen, in a nutshell explores the concept of emergence and the origin of life in a way that has never before been attempted. (Emergence is the opposite of reductionism, the view that any system can be explained by understanding its parts.) Or to put the aim of this book in question format:
How did non-living chemicals become alive? What happened in 100 million years that led to the origin of life?
Hazen explains a major objective of his book:
"To describe our present imperfect state of understanding--and to offer a conceptually simple scenario [or theory] for life's chemical origins. This theory synthesizes two fundamental frontier efforts: the mind-expanding theoretical field of emergence and the astonishing experimental discoveries in prebiotic [that is, before life] chemistry [some made by Hazen himself]."
Thus the parts or sections that make up this well-written, easy-to-read, and somewhat personal book are presented in the following logical sequence:
(1) Emergence and the origin of life. (Answers, among other things, the question: "How does one begin to tackle the chemical complexity of life?")
(2) The emergence of biomolecules (such as amino acids, sugars, hydrocarbons, and nucleic acids).
(3) The emergence of macromolecules (such as carbohydrates, proteins, DNA, and RNA).
(4) The emergence of self-replicating systems. ("For origin-of-life researchers, creating a self-replicating molecular system in a test tube has become the experimental Holy Grail.")
Don't worry! The science presented in this book is presented well and Hazen explains any unfamiliar terms. For those familiar with the origin of life literature (like myself), they will find some of this book a review but I found there was new stuff presented that I had not read before.
Be aware that this book does not present definitive answers. Hazen elaborates:
"Life emerged...through some real process. Molecules formed, they combined, they began to replicate. Much of that history is...lost forever. We will never know exactly where or when the first living entity arose, nor is it likely that every chemical detail of the process will ever be known for certain. Scientists flesh out the process with their own favorite origin stories...And even if we do succeed in making life in the lab, there's no guarantee that that's exactly the way it happened 4 billion years ago."
Between each of the four sections presented above, there is a short "interlude" where Hazen presents his opinions on various topics. I especially found the interlude entitled "God in the Gaps" interesting.
Finally, in the book's middle are eight plates comprising almost thirty black and white pictures of mostly the main people involved in origin of life research. As well, there are more than twenty diagrams peppered throughout the book to enhance understanding.
In conclusion, this book traces the efforts of scientists from all over the world as they confront nature's most enduring mystery. If you like mysteries like I do, then you'll like this book!!!
(first published 2005; forward; preface; prologue; 4 parts or 19 chapters; epilogue; main narrative 245 pages; notes; bibliography; index)
29 of 30 people found the following review helpful
on July 15, 2006
The origin of life on earth is still one of biology's great mysteries. Hazen makes it clear that we do not yet know the answers. Many interesting proposals have been made, and new evidence is coming in all the time. No one theory has yet won out.
Creationists have, of course, focused on origin of life research in recent years as showing up the weaknesses of science. I think this book is a useful counterpoint to this. Maybe we don't know it all yet, but the science in this area certainly has not run into any solid roadblocks that require God to get over.
The present situation in origin of life research reminds me of the middle 1800s, when Darwin was working on his theory of evolution by natural selection. At that time, many hypotheses were on the table to explain the diversity of life on earth and in the fossil record. Some hypotheses had more support, some had less; all the proposals had problems. Back then, the creationists were convinced that further study of nature would bring scientists to the solid conclusion that God created the world. Creationists engaged in serious biological research, in the hope that the results would bolster their views. It didn't turn out that way. I suspect the same pattern will hold true in origin of life research. Check back in a few decades.
88 of 100 people found the following review helpful
on October 18, 2005
I found this a refreshing account of origins of life research. In some ways the question of evolution is so hounded by the obsessions of Darwinist and Intelligent Design fanatics both that it is nice to find a biology text on evolution (and this is indirectly a question of evolution) that plainly explains what we don't know, and proceeds to explore an immensely difficult subject. There is an ironic critique of Intelligent Design here. You can't really succumb to the design cop out because you would still have to explain everything anyway, as here. And that requires patient science for what is not a simple riddle. The keynote perspective here is that of emergence as a new category standing in counterpoint to the laws of thermodynamics.
33 of 35 people found the following review helpful
on January 3, 2007
Robert Hazen has written an amazing book. He explains the concept of 'emergence' in a way that makes me believe he must be a masterful teacher. In fact, the book made me wish I did my PhD thesis research in his laboratory back in the late seventies. Every morning when I drive over the washboard bumps in my gravel driveway, I am reminded of this book (those who have read it will understand why.
Then the author explains the history of origin-of-life research and the instrumentation that made the work possible. At that point, Dr. Hazen presents several dominant theories on whether metabolism, membranes, or RNA evolved first. Having worked with RNA since 1976, back before Molecular Biology was all about knowing what kits to buy, I already knew RNA was much too fragile in the presence of most multivalent cations to have evolved first. Apparently most Molecular Biologists have missed this obvious point, but Dr. Hazen has not.
The author applies a fresh pair of eyes to the subject because he is not a product of the 'academic apartheid' (Lynn Margulis' term from the book jacket) that had plagued Biological Research for the past few decades. He is a geophysicist and does not receive the bulk of his funding from the NIH or NSF. He understands the chemistry of the early Earth and of life far better than most of the 'experts'.
This book is more than just a primer on the emergence of life. He describes, more gently than I would, much of the behind-the-scenes back-biting that is, unfortunately, a part of getting papers published and obtaining grants in science today. Anyone considering a career in research should read those parts and internalize those lessons.
To summarize, the book gets five stars for originality, scientific content, readability, and insights into the realities of modern scientific research. If you only read one book on the origin of life, this one should be it!
19 of 19 people found the following review helpful
on December 13, 2007
Hazen surveys the theories of life's origins, organizing them by the stage of producing life to which they pertain, the creation of: biomolecules (e.g. simple amino acid); macromolecules; self replicating systems. Unfortunately, theories are not neatly packaged like that, and Hazen is not all that disciplined about when to present material; for example, he does not like to break up a discussion of a scientist's work, except for his own. In fact he would rather sequentially discuss different theories than to attempt a synthesis, taking a kind of an historical approach. Still, he usually writes clearly, and recapitulates frequently, so while I didn't come away with as firm a grasp of the material as I would like, I enjoyed the book a lot, and am eager to read another good book on the subject. I exclude the section on emergence, which could have been mostly eliminated, and certainly been much better written.
I was most surprised by the fact that there are all kinds of sources for biomolecules, including outer space. Also, rocks and minerals can potentially play multiple roles in the emergence of life: providing energy, catalyzing reactions, concentrating biomolecules selectively, and even, as clay particles, promoting the multiplication of lipid vesicles and the incorporation of RNA into these vesicles. One of the most intriguing theories is one of the newest: that the pyruvates, biomolecules which are abundantly formed even in the absence of life, can form a kind of scaffolding to collect the bases which are the key components of RNA. It is not then too big a jump to think the bases might link and forma proto RNA, and we know RNA can catalyze energetic reactions as well as its own duplication.
One advantage of the historical approach, is that the reader develops a healthy skepticism, to mirror Hazen's. Hazen describes important failures as well as successes. I was greatly surprised to learn that the proportion of light carbon to heavier carbon in a molecule cannot be used as a guaranteed indicator that the molecule was created by a life form. Also, unlike most authors, Hazen, despite being a positive, relatively humble person, does not mind being critical of other scientists, especially those with big egos, and those willing to abuse graduate students.
13 of 13 people found the following review helpful
on November 22, 2007
As Robert Hazen explains, the complexity we see in the world is not at odds with the Second Law of Thermodynamics. What happens is that in the presence of an energy flow, patterns form in systems which help dissipate that energy.
We need complexity and patterns for life to evolve. Once life begins, evolution can produce more and more complex life forms. But how do we get to the first life form? As the author says, we need prebiotic evolution. Three scenarios are considered. One is that metabolism came first, and that once started, chemical evolution led to replication and membranes. Another is that replication came first, either RNA or a precursor. And the third is that life began as a cooperative phenomenon arising between metabolism and genetics. Hazen seems to like the third possibility, but he does not pick any. I'll pick an option, however: I like the first one. Life reduces carbon dioxide, and I like the idea of chemical evolution getting started once some rudimentary sort of metabolism existed.
The author tells us about some of the specific metabolism-first models. An early one was Sidney Fox's protenoid model. This model was popular at first, and it has been challenged in more recent times, but I think it is worth studying. Another idea Hazen covers is Christian de Duve's "Thioester World." However, de Duve fails to specify the exact chemistry he has in mind to get to life in this manner. Again, I think de Duve's ideas merit serious study. And the final of the metabolism-first ideas is Gunter Wachtershauser's Iron-Sulfur world. This is pretty specific: hydrothermal vents contain carbon dioxide, water, ammonia, hydrogen sulfide, and energy. This is an autotrophic model: the prebiotic structures manufacture their own nourishment rather than simply obtain it from some sort of prebiotic soup. My wild guess is that this is the wrong track: life led to RNA, and I think such delicate molecules as RNA would be tough to produce in such an environment. In addition, we'd need better evidence for specific metabolic cycles that are consistent with this model. But once again, I think these ideas merit careful study.
Next, we read about the "RNA world." RNA is indeed a very special molecule. Once it exists, it can replicate and it can make proteins. That suggests that replicators may have come "first," maybe with a precursor to RNA and then RNA itself. I don't quite buy this argument, because I do not see how we go through chemical evolution to produce something as complex and delicate as RNA without a succession of metabolizing structures which incrementally improve.
Hazen then discusses what sort of replicators must have preceded RNA. Perhaps some PNA (peptide nucleic acid)? We get to read about some a very speculative idea: a "PAH world" (PAHs are polycyclic aromatic hydrocarbons). I think this is very interesting: the idea is to come up with something much more resilient than RNA even if it is far less efficient as a replicator.
Are we getting closer to figuring out the rough process by which life originated? Well, maybe so. But I think we have a very long way to go. On the other hand, that's one of the things that makes this field so exciting.
I recommend this book.
13 of 13 people found the following review helpful
on January 20, 2008
Hazen surveys then-current ideas and research on the origins of life. He makes considerable effort to keep it exciting and personal by including stories of research as it happens. I especially appreciated the non-magical discussion of emergence in early chapters; it is a phenomenon which unfortunately is used as an excuse by some to hide or inject magic into the process. Hazen reviews what has been done and what has not been done in the exploration of various ideas about prebiotic chemistry, the RNA World theory (which is accepted by most biologists today) and current cellular life, and attempts to bridge the various stages. The book may leave the reader with the impression that the field is rather chaotic with huge scientific challenges remaining, since Hazen does not come to many conclusions. Unfortunately this impression seems to be accurate. Perhaps young proto-scientists should view this in a positive light: there is still a lot of scientific discovery remaining.