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Life on a Young Planet: The First Three Billion Years of Evolution on Earth

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Australopithecines, dinosaurs, trilobites--such fossils conjure up images of lost worlds filled with vanished organisms. But in the full history of life, ancient animals, even the trilobites, form only the half-billion-year tip of a nearly four-billion-year iceberg. Andrew Knoll explores the deep history of life from its origins on a young planet to the incredible Cambrian explosion, presenting a compelling new explanation for the emergence of biological novelty.

The very latest discoveries in paleontology--many of them made by the author and his students--are integrated with emerging insights from molecular biology and earth system science to forge a broad understanding of how the biological diversity that surrounds us came to be. Moving from Siberia to Namibia to the Bahamas, Knoll shows how life and environment have evolved together through Earth's history. Innovations in biology have helped shape our air and oceans, and, just as surely, environmental change has influenced the course of evolution, repeatedly closing off opportunities for some species while opening avenues for others.

Readers go into the field to confront fossils, enter the lab to discern the inner workings of cells, and alight on Mars to ask how our terrestrial experience can guide exploration for life beyond our planet. Along the way, Knoll brings us up-to-date on some of science's hottest questions, from the oldest fossils and claims of life beyond the Earth to the hypothesis of global glaciation and Knoll's own unifying concept of ''permissive ecology.''

In laying bare Earth's deepest biological roots, Life on a Young Planet helps us understand our own place in the universe--and our responsibility as stewards of a world four billion years in the making.

In a new preface, Knoll describes how the field has broadened and deepened in the decade since the book's original publication.

288 pages, Paperback

First published April 6, 2003

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About the author

Andrew H. Knoll

11 books54 followers
Professor of Natural History and a Professor of Earth and Planetary Sciences at Harvard University.

More info about Knoll's work on the Knoll Lab website.

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Displaying 1 - 30 of 65 reviews
Profile Image for Leo.
4,311 reviews390 followers
June 13, 2022
Interesting subject overall but I had a hard time focusing on the audiobook. Probably a more of a me thing but might read the physical book someday
Profile Image for Peter Tillman.
3,638 reviews329 followers
March 13, 2018
This is an appealing combination of a natural history of the first three billion years of life on Earth, which is (roughly) the author’s professional specialty, along with a scientific memoir of his pertinent field work. Knoll is a good writer, and despite the book’s publication 15 years ago (2003), you won’t go seriously astray. I read this book in parallel with Nick Lane's Mitochondria book https://www.goodreads.com/book/show/3... (which I found a much harder read). They both cover some of the same ground, but the differing approaches of a field paleontologist and a laboratory biochemist make for some interesting "compare & contrast" moments. They're both good writers and good scientists. I was more comfortable with Knoll, but then I’m a geologist.

Knoll intended his book to be understandable to a general audience, but there are some frustrated comments from readers here suggesting that he didn’t always succeed. I think the book will work best for readers who have some previous knowledge of geology and paleontology. General readers may want to do some skimming, or better, some homework. Knoll does supply a pretty good selection of color and b/w photos, and cladograms! --which remind me of how far back in the dim past my classwork on this stuff was. And the perils of trying to be an autodidact, later on.
Profile Image for Manybooks.
3,126 reviews104 followers
February 24, 2021
So yes, for a very much and heavy duty science based tome featuring a detailed (and as such by mere necessity also and of course replete with a multitude of required facts and figures) analysis and presentation of what life was theoretically but obviously most probably appearing as during our planet’s, during the earth’s first three billion years of its existence, of its early history (and how life on earth evolved and slowly but steadily changed during said time, starting as single celled and slowly changing to finally appearing as also multicellular), as a reader who has in fact NOT TAKEN ANY academic courses in biology, physics, chemistry and such since around 1983 (since almost forty years ago in grade eleven), I do find it both wonderful and am indeed hugely appreciative that in Life on a Young Planet: The First Three Billion Years of Evolution on Earth, author Andrew H. Knoll in my opinion totally and utterly gets it right so to speak and that he, that Knoll is therefore absolutely successful demonstrating and showing us the early evolutionary history of the earth, and yes indeed, that Life on a Young Planet: The First Three Billion Years of Evolution on Earth is also textually geared towards a so-called lay audience, presenting scientific details and data clearly, succinctly and concisely but also making sure to not overwhelm readers with too either much jargon or too much superfluous data.

And although sometimes Andrew H. Knoll’s featured text does have a bit of a tendency to be rather repetitive (and to therefore mention the same development of life, to point out the same evolutionary scenarios over and over again), well in my humble opinion, that very repetitiveness is actually and in fact both required and very much necessary to focus on the main thesis statement of Life on a Young Planet: The First Three Billion Years of Evolution on Earth, namely that during the first three billion years of the earth’s five billion year history, life was basically entirely one-celled for rather much of said time, was totally prokaryotic in nature, that one-celled organisms thus started life on earth, are the root of the so-called tree of life and that ALL other forms of multicellular, of eukaryotic life (from basic plants to mammals such as us humans) have of course evolved from this one-celled life root.

A both enjoyable but first and foremost educational, wonderfully enlightening and indeed also delightfully easy to comprehend and internalise personal reading experience Life on a Young Planet: The First Three Billion Years of Evolution on Earth has been for me (a solid four stars for Anthony H. Knoll’s presented narrative, for his findings and how he totally makes his text so easily approachable, but happily, gladly increased to five stars, as I not only find Knoll’s bibliographic details extensive, for supplemental research ease, I also really do very much appreciate that Anthony H. Knoll in fact has totally separate bibliographies after each of his fourteen section, for each of his chapters).
Profile Image for Lindsay.
1,263 reviews222 followers
November 20, 2019
A fascinating grounding in what we know about the earliest life on Earth and how we know what we know. The book doesn't shy away from explaining controversies in detail, and gives a solid idea of where the boundaries of this field lie, both in terms of what was known when it was published, and what is likely to be forever unknown.
Profile Image for Claudia Putnam.
Author 5 books125 followers
October 20, 2018
I loved almost every moment of this book. Considering it's mostly about slime--AKA bugs (prehistoric germs), algae, fungi, and these other weird things called archaea, you'd think it wouldn't have been so hard to put down. But Knoll has a poetic sensibility (and a tendency to start out each section with a literary epigraph that warmed my heart). And this, my friends, is the stuff of life. The origin of life. What turned our planet from a hostile place without any oxygen, gradually, into a place where creatures like us could breathe. And what survives and brings life back each time the planet dies, as it does, either a little bit or a lot, every 26 million years.

You know what's interesting? You think it's climatologists, 97% of whom are repeatedly said to agree, who are yelling about climate change, don't you? Well that may be. However, I've been reading these books lately about the history of life on Earth. John McPhee's Annals of the Former Earth. Peter Brannen's The Ends of the World. I'm in the middle of Douglas Erwin's Extinction (about the Permian Extinction, in which 96% of land and marine life died). Some summaries of Peter Ward's many, many books. And this here book. And I'll tell you what. It ain't just climatologists. It's biologists, earth scientists, geologists, biostratigraphers, planetary scientists, evolutionary biologists, paleontologists...probably some other ologists... anyone involved with the history of life on earth... all have been growing increasingly alarmed for quite some time.

Why? Because life on earth has died over and over again. In a big way.

Why? Due to changes in atmosphere and ocean chemistry.

Why? Carbon levels, most of the time.

Why? Rate of carbon levels in the air and acidification in the ocean, or oxygen depletion in the ocean.

I'm not going into all of it here, but to find out more you can read this book or a bunch of others concerned with the history of life on earth. This just happens to be a particularly interesting and pleasant one to engage with. The point is that it's germs that save the world, but also that changing the balance at the slime level--killing off plankton, which we're doing, for instance--destroys life on earth.

The good news is thanks to slime, life rebounds. It takes, sometimes, tens of millions of years, and it's usually completely unrecognizable, but you get dinosaurs and sometimes primates. It took a couple of rounds of extinctions to get animals at all.

BTW, if you write science fiction set on planets, you'd better read this book or another one having to do with single-celled organisms and their development in relationship to their environment. You'd also better read about RNA and lateral gene transfer. You might as well read this book! Because it's not just about how cells turn into animals (which still isn't completely understood) but about how cells create environments capable of supporting more complex life. I read all too many SF books with no foundation whatsoever in planetary science or evolutionary biology.

Criticism, and I'm sorry to say I think this is personal: Knoll is quick to offer adjectives associated with people he mentions. The "affable" so and so. The "brilliant" whos-its. These adjectives are always applied to male scientists. Female scientists, always duly credited at least, are simply named. I'm not sure he's aware he's doing this. I noticed that in his acknowledgments he mentions not a single female scientist. I can't fault him, I suppose for not having any female friends, and I know that female geologists and biologists are still rare, but... in contrast, the paleontologist Douglas Erwin lists quite a few women in HIS acknowledgments (along with Andrew Knoll, as it happens), for Extinction, which as I said I am currently reading. These are personal choices, of course, but dude.

One thing I did appreciate was that Knoll did seem to go out of his way to include different points of view, and to be generous--as far as I could tell, which probably isn't very far--when there were controversies. Since there can be a lot of mean-spiritedness and territoriality among scientists, I was glad of this.
Profile Image for Jamie Smith.
488 reviews76 followers
September 27, 2019
Life finds a way. Evidence indicates that it first arose out of simple organic precursors within a billion years of the planet’s formation, but it would be another three billion before the Cambrian era ushered in the astonishing diversity of multicellular forms whose descendants populate the earth today. Before photosynthesis, at a time when the atmosphere contained only trace amounts of oxygen, early bacteria were using chemosynthesis to obtain the nutrients they needed from methane and sulfur compounds. From some ancient ancestor the three domains of cellular life emerged: prokaryotes (or bacteria), eukaryotes (cells with a membrane-bound nucleus), and the archaea, not recognized until 1977, and most commonly associated with life in the deep ocean thermal vents.

Without shells or skeletons, the remaining traces of early life are faint and can be easily confused with naturally occurring chemical processes. The book has a chapter analyzing the incident from 1996 where it was announced with great fanfare that a Martian meteorite had been found which contained evidence that at one time life had existed there. The author does a good job examining four possible arguments for this, finding three of them unsubstantiated and the fourth improbable but intriguing.

One of the more interesting ideas about the evolution of early life is how mutable it was. There is evidence that cells swapped genetic material regularly, either though ingestion or absorbing it from dead material, and natural selection promoted the combinations that improved survivability. Along with this is the idea that at some point a cell took in mitochondria, and instead of consuming it formed a symbiotic partnership where the cell provided protection and nutrients and the mitochondria generated energy for cellular chemistry.

Photosynthesis apparently evolved at least half a dozen times, but it is surprisingly inefficient. Evolution can only work with what it already has and so tends to cobble together new abilities using slight modifications of what is already there. The changes that are successful survive and can mutate further. As a result, photosynthesis today is not some elegant chemical wizardry but a Rube Goldberg contraption where water and sunlight go through multiple steps before turning into carbohydrates and free oxygen.

Evolution is driven by many processes. Environmental changes can spell disaster for some species but open up new opportunities for others. Some time between 2.4 and 2.2 billion years ago photosynthetic bacteria reached a critical mass and the amount of oxygen in the air and sea rose sharply. Oxygen was toxic to the bacteria which used methane and sulfur, and their demise opened the door for the rapid evolution of new oxygen-based life forms.

The book ends with the start of the Cambrian Explosion about 543 million years ago. Although multi-cellular algaes had existed for a long time, conditions changed to favor the survival of larger animals and new body forms evolved quickly and in astonishing profusion.

So, what was the tipping point that led the way to the modern world after so many millions of years of simple cellular existence? It was most likely a combination of several factors, including changes to the environment. The author discusses the Snowball Earth hypothesis. The icing over of the seas would have broken down not just photosynthesis, but also the carbon cycle, leading to the build-up of iron in the oceans. The result would have been lethal to almost everything, and the eventual thaw would have opened up vast areas to be exploited by opportunistic eukaryotes, much the way the sudden demise of the dinosaurs opened up the world for mammals to occupy new niches.

Dinosaurs are sexy. So are dramatic fossils of plants and animals. Microscopic single cell life is not sexy, but it has its own story to tell about the early earth and the forces that led the way, after three billion years, to the planet we know today. This book is worth reading for anyone with an interest in paleontology.
Profile Image for Troy.
22 reviews30 followers
May 31, 2016
Andrew H. Knoll is a paleontologist who is particularly conversant with the integrative approaches of modern day evolutionary science. Rooted in the rocks, he writes with skill about the geological and geophysical processes at work in early earth formation, and their implications for the evolution of life. He explains the complex geochemistry that became, in time, a biochemistry. He describes the so-called evo-devo (I.e., evolutionary developmental biology) revolution with verve-both as an observer, and a participant/contributor. He describes in some detail how the evolution of life is largely one of microbiologic changes through geologic time. Some critics fault him for leaving the good stuff for the end-a bizarre criticism given that the "good stuff" (I.e., complex multi-cellular animal life) has only been around since very recent times in geological terms. Knoll deftly defeats this prejudice by pointing out that while animals are the kings of morphological variety, it is the microorganisms that are the exemplars of metabolism. Microbes have evolved diverse mechanisms for surviving on a catastrophically evolving planet. It is in fact, the microbes that made the planet habitable for animals. This is a story as epic and heroic as any produced by evolutions most complex, and ridiculously recent, product. If I had a quibble with the book, it was with the decision to include the final chapter about the possible Martian origin of terrestrial life. Not to say this story wasn't interesting, but it would have been better left to another book. Finally, Knoll's conclusion attempts to reconcile the seemingly ever-opposed science and religion and is reminiscent of Stephen J. Gould's "twin magisteria" argument. The stronger part of his conclusion reminded us that past may be prologue: That current action or inaction may have consequences in what could be, but doesn't have to be, our own evolutionary endgame.
Profile Image for John.
271 reviews17 followers
February 5, 2017
On one hand, this book is remarkably accessible. This book could be going straight for the deep end, requiring a background in paleontology, molecular biology, and geology. For somebody with none of these things, beyond fuzzy memories of grade school science and some popular science reading, you will understand most everything that is happening here and find quite a bit of it compelling.

On the other hand, this book is really scattered. Almost every chapter starts with some "We're here in this remote place" Indiana Jones-style posturing, almost always to reveal two paragraphs later that they've dug up yet another chunk of chert and never really make anything of the place again, too deep inside the analysis. Sometimes it flows really well, and sometimes it really gets stuck inside of current academic debates. Holistically, though, you aren't always given a sense of what the significance of what was going on. It really needed much more in the way of summarizing what had been said. The epilogue's sudden focus on the present comes out of nowhere.

Overall, this book is good at leading you to interesting ideas but not that great at leading you out of them with a coherent sense of where you had been. I think a more explicit sense of continuing along a timeline, whether the Earth's or the author's own development, would have helped considerably. Nonetheless, I really feel better informed about a lot of these areas and found the details intriguing, though I never did form them into a larger mental picture.
Profile Image for Stephen Palmer.
Author 38 books39 followers
March 20, 2015
I very rarely give 5/5 reviews, and then only to classics, but this is too good to receive four stars. It's an exceptional guide to the current state of thinking about the three billion years of the evolution of life leading up to the Cambrian Explosion. Written by an expert in the field, with a whole professional life behind him, it's superbly, clearly and engagingly written - I haven't read a natural history book as good as this for a while. All phases of life are covered, from the very earliest up to the Cambrian Explosion itself at 541 million years ago. The author is fair-handed, giving alternative evaluations where appropriate and mentioning all the main players in the field. Nor do you need much scientific knowledge to appreciate this book; it's written with style and clarity. In a nutshell - exceptional.
Profile Image for Clyde.
793 reviews54 followers
May 21, 2018
The study of the history of life on this planet has come a long way. Knoll pulls it all together nicely in this well-written volume. Though not simplified, the clear and logical writing make it accessible to the educated and curious layman. The numerous charts, photographs, and diagrams are a huge plus.
First Knoll sets the framework for what the book aims to achieve. Then each chapter centers on a different aspect of the journey of life. As the book builds, we learn how biological, physical, chemical, geological, and environmental processes interacted over deep, almost incomprehensible spans of time to cumulate in the wondrous explosion of multicellular life in the Cambrian (and thus eventually produce the world that we know).
Very good book.
Profile Image for Tim Martin.
715 reviews43 followers
April 11, 2020
This was a good, readable (occasionally a little technical) popular science book on the early years of life on Earth, before abundant animal fossils started appearing it the fossil record, well before dinosaurs, before even trilobites, the most famous of Paleozoic marine fauna. In most popular science works on the history of life on Earth this is a time usually dispensed with in a few pages (which is too bad though perhaps understandable). The geological eon that is the focus of this book was a time when the world was alien, with at times relatively little oxygen, or covered almost to the equator in ice, or when the largest organism for staggeringly long periods of time was bacteria, a time that in some locations leaves abundant fossils, but are not a bone or a shell or carapace sticking out on a cliffside but microscopic ones, only able to be seen in a lab after preparation (though one learns on reading the book, towards the end there were definitely fossils that could easily be seen with the naked eye or even before the end if one knows what one is looking at such as with stromatolite fossils).

It is a frustrating time period to study the author clearly shows, the focus of the book being primarily the Proterozoic Eon (between 543 million years and 2.5 billion years in the past, when oxygen first appeared in the atmosphere and the first multicellular organisms first appeared in the fossil record, between the current Phanerozoic Eon – “age of visible life” and the Archaean Eon, which goes back to 4 billion years ago, an eon during which the Earth’s crust had cooled enough to form continents and life first arose). Finding rocks of the Proterozoic are difficult except in a few places as anything laid down has had a very long time to be transformed into metamorphic rocks or taken back down deep into the Earth’s crust. In addition life often didn’t readily fossilize lacking as it did for most of this eon anything like a shell, life could often only be told from biomarkers (such as the presence of certain types of carbon) and even then often with some controversy, but it is a rewarding and interesting eon to study author Andrew H. Knoll shows, a truly alien world and a world that gave rise to the famous Cambrian Explosion (an event about 541 million years ago when, in geologic timescales, all the major modern groups of animals suddenly appeared and from then on in many places animal fossils would become abundant and often very easily seen).

The author in a very understandable manner imparts some of the basic tenets of the study of evolution; of “the cumulative nature of biological diversity” (“the history of guilds – of fundamentally distinct morphological and physiological ways of making a biological living – is one of accrual”), of “the coevolution of Earth and life” (“Both organisms and environments have changed dramatically through time, and more often than not they have changed in concert”), that life is a “planetary force in its own right, joining tectonics and physical chemistry in the transformation of air and oceans,” and that in order to have biodiversity, one must have “a permissive ecology [that] allows poorly functioning novelties to persist,” that there is “an ecological landscape in which competition for resources is rare or weak” (often occurring when new environments open up due to geological change or when a mass extinction event wipes the slate clean). Nowhere more than the Proterozoic can one see how these things are all true, of how massive geological events both wiped out life but also allowed for it to flourish, of how the evolution of bacteria and other microbes lead to vast geological changes in atmospheric, climatological, and oceanic composition, of the nature of the very rocks themselves.

I loved the excitement and patient teaching – illustrated with many diagrams and black and white and color photos – of what fossil organisms paleontologists study from the Proterozoic and how and where they find these fossils and how they study them (and know they aren’t just seeing geochemical and geophysical processes having nothing to do with life, important especially in the last major chapter, one covering applications of paleontological knowledge in the search for life on Mars and elsewhere, spending a lot of time on the famed Martian meteorite ALH-84001).

You learn a lot about bacteria, of how they are recognized in the fossil record, of their relationship to modern bacteria, their ecological role, of even the structure of bacteria. Most especially you learn a lot about cyanobacteria (“common today in coastal habitats where very salty water or other environmental challenges restrict invasion by animals”). Clearly Knoll had a soft spot for cyanobacteria, calling them “the working-class heroes of the Precambrian Earth – the main primary producers in early oceans and the source of the oxygen that transformed terrestrial environments.” His coverage of them was interesting, delving into why “populations preserved 750 million, 1 billion, or even 2 billion years ago are essentially indistinguishable from living forms” in sharp contrast to most plants and animals.

One also learns a lot of cell biology, understandable since among other things for most of the Proterozoic life was unicellular. You learn a lot about the function of DNA, RNA, mitochondria, the endosymbiotic origins of mitochondria and chloroplasts (how different genetic lineages became fused, of how these parts of cells owe their origins not just to distinct genetic lines, but were themselves once, a very long time ago, separate organisms). Endosymbiosis was fascinating, of how one cell becomes “an integral part of another,” showing how often life is “not so much “red in tooth and claw” as “green in mergers and acquisitions.”

The reader also learns about some of the fossils assemblages from the Proterozoic, such as the famed Ediacaran fossils, named for the Ediacara Hills of South Australia, “the exposed roots of the metazoan tree: the earliest representatives of animal phyla that blossomed into diversity in the ensuing Cambrian,” a formation of “large, complicated organisms, as well as simple tracks and trails unambiguously made by animals,” though also a formation of very strange fossils, including disk like jellyfish like organisms that lived on the seafloor (“extinct taxa that record an early radiation of anatomically simple animals”) and vendobionts (“complex, often leaflike forms made up of repeating tubular units”), strange organisms that “provide a Rorschach test for paleontologists,” as individual fossils “have been interpreted as colonial cnidarians, as segmented worms, as primitive arthropods, seaweeds, lichens, and more.”

The Doushantuo fossil formation is also well covered, dating to about about 635 and 551 million years ago, a remarkably well preserved formation of microscopic aquatic life between the Ediacaran fossils and the famed Cambrian ones, a formation that appears to show the first bilateral animals, algae fossils with cells preserved intact, and “animal eggs and embryos in the early stage of growth,” though “we don’t know what kind of adults might have developed from the Doushantuo embryos.”

Well written, a little technical at times on some aspects of genetics, cellular biology, and geochemistry though I think I also at times wasn’t patient with these small sections (they were accompanied by charts and diagrams as well as when appropriate photographs), I liked the tiny passages (usually just a paragraph or two) of the author’s experiences in the field with different formations (accompanied by what the rocks look like in the field). There are color plates in the middle, black and white illustrations throughout the book, and an extensive index and a by chapter organized section of suggestions for further reading.

Profile Image for Madeleine.
724 reviews16 followers
December 23, 2008
Thing to keep in mind: The First Three Billion Years of Evolution on Earth sounds fascinating, but nothing much bigger than a microbacteria actually *evolved*. This book ends just as stuff starts growing legs and arms and wings and crawling out of the ocean and generally becoming *interesting*.

This book should be named: "rocks--with microscopic fossils, in places with funny scandanavian names." But that's probably what you should expect when you get book recommendations from geologists.

Joking aside, I definitely learned stuff. I'd suggest the book to anyone (like me) who only ever took two years of biology, and both years were taught by someone who didn't believe in evolution. But I'm excited to move on to the next phase of prehistory for my next evolution book, and read about things with more than one cell. There's only so long you can read about bacteria and then get really excited because instead of reading about bacteria you are now reading about....oooooo...algae!!!

On an unrelated note, I think someone put a curse on Alaska Airlines.
114 reviews
November 15, 2012
Very well researched and presented. Covers a time period with which most are not familiar. The author presents the research as a good scientist, with a healthy dose of skepticism, while basing conclusions on well established research. He points out areas where more research is needed. He has his own theories, and is careful to present them as such. A good read, especially if you've heard of snowball earth and want some more background.
Profile Image for William Bies.
227 reviews38 followers
July 25, 2020
The Cambrian explosion some 543 million years ago, which marks a radical expansion of multicellular life-forms and the beginnings of the higher taxa known to us today, represents in fact a rather late episode in the history of evolution on our planet. There is always a charm to investigating origins, and the paleontologist and geologist Andrew Knoll does not disappoint in his survey of the early prehistory of the earth, from the Hadean epoch four billion years ago, when the planet had just formed and emerged from the late heavy bombardment, up to the Cambrian, thus embracing an unimaginable expanse of time of over three billion years.

Knoll leads off with the tree of life as reconstructed from genetic sequencing of modern-day organisms, divided into the three kingdoms of eucarya, bacteria and archaea. Right from the start, the reader can see why Knoll’s account of evolutionary prehistory in this work will be appealing. He tells us not merely about the diversity of living organisms, but also about the geological cycles in which they are inextricably implicated, such as nitrogen fixation, to name one instance. Thus, one encounters one of the main themes of the paleontology of primitive life, the interdependence between life and the chemical and geological constitution of the earth’s environment. But there is more. Knoll enters into some of the technical complexities that crop up when seeking to reconstruct the phylogenetic process, such as what characters can be used to make what inferences and how to root the branches of the tree, as well as the complications introduced by horizontal gene transfer (which presumably was important during the early period).

Chapter three gets into the subject in earnest with a discussion of the signatures of life to be found in the rocks at Spitsbergen (an island in the north sea off Norway) from circa 600 to 800 million years ago. Microfossils are much more difficult to interpret than the macroscopic fossils of dinosaurs and the like with which everyone is familiar. Knoll leads us through relevant terms of art such as chert, cyanobacteria and stromatolites, and how these traces of early organic life can be distinguished from what one might expect from inorganic processes. One can catch a glimpse of why his field can be so fascinating; to draw an analogy, it is somewhat like what makes chamber music more interesting to the connoisseur than symphonic music: the composer of a string quartet is faced with the challenge of drawing more from sparser instrumental resources. For a warning about possible pitfalls paleobiologists face, see chapter four on the rather more difficult to assess 3.5-billion-year-old sedimentary rocks at Warrawoona, Australia.

The emergence of the first life from prebiotic precursors forms the topic of the next chapter. Here, a quick review of biopolymers and their likelihood of formation under prebiotic conditions. The succeeding chapters cover a number of great events in the earth’s geological history: the oxygenation of the atmosphere around 2.2 billion years ago, the origin of eukaryotes via endosymbiosis, the rise of animals and another look at the Cambrian epoch, with a view to the environmental factors that may have promoted rapid diversification, the breakup of supercontinents and the snowball earth, a brief episode 710 million years ago when glaciers advanced to cover almost all of the planet and posed a threat to the continued existence of life: how does one get out of such a deep ice age? In the event, volcanos came to the rescue by venting carbon dioxide into the atmosphere.

Lastly, the reader will find in chapter thirteen, ‘Paleontology ad astra’, a good treatment of the meteorite recovered from Antarctica, ALH-84001, which made the news a while back when Nasa scientists claimed it to bear signatures of bacterial life on Mars. Knoll explains why we can be sure it is from Mars and applies what the reader will have learned earlier in the book to an analysis of how credible the sensational claims are, in fact.

Summary: Knoll’s account of the early prehistory of life up to the Cambrian, the conventional starting-point of paleontology, is very engaging. Some nice features of his exposition are that it is always concretely rooted in what has been discovered at specific sites across the globe (with photographs and travel narratives) and, paying attention to the grounds upon which we know what we know, he goes into more technical detail than is usual for a layman’s account, yet not so much so that it ceases to be easily readable and enjoyable (many informative figures and diagrams). He trusts the reader to be intelligent enough to follow. The reader who stays with him will be treated to a rewarding overview of the grand themes he sets out to explore in the prologue: the cumulative nature of evolution, the coevolution taking place between organisms and their environment and the startling rise of life to become an equal player with the physical tectonic, oceanographic and atmospheric processes that codetermine its fate.

In a four-page epilogue, Knoll sums up his narrative with a reflection on how the picture of the world’s origin afforded by the modern empirical sciences compares with the great mythological creation stories of primitive peoples, the Upanishads or the canonical scripture. Not only are we intimately connected with cosmic happenings, as in the brewing of the elements inside previous generations of stars during stellar evolution, but we now know much more than the mythological authors did about the codependence of all forms of life, in particular, of modern man on the single-celled organisms that form the focus of his book on the first three billion years. From the detached perspective of science, man does not figure very prominently until very late, when he becomes a driving factor behind ecology (the first trace of early man in the fossil record is the extinction of the megafauna; we have been at it all along and still are today, notwithstanding the rosy Rousseauian ideal of primitive man, however popular it may be to people in our day). But his real point goes deeper. The creationists among our contemporaries do not perhaps register the steep price they must pay, for not only must biblical literalists reject evolutionary biology, to be consistent they must oppose virtually all of modern empirical science. Not only does geology deliver a timescale that is much too long for their calculations, but also the physics and chemistry that underlie radioisotopic dating cannot be dispensed with without overthrowing the entire edifice of scientific knowledge. Hence, modern creationists face a stark either-or alternative (the situation is entirely different with historical creationists up to the nineteenth century, when the position could still have been intellectually respectable and the scientific chronology of the earth’s prehistory was just emerging). Does it do credit to God—Knoll asks—to suppose that he made the world as it is, replete with evidence of an ancient past, just to fool us? Knoll declines to pursue his line of thought any further, but we can. Creationism in its present-day guise is almost exclusively a product of fundamentalist evangelical Protestantism in America. Evangelicals, even the most educated among them, tend not to be very intellectually sophisticated at all, certainly when measured against the standard of Roman Catholics or mainstream Protestants in Europe (to prove this to oneself, one need merely consult, say, William Lane Craig’s hapless apologetical attempts to do philosophy, which are risibly callow and lacking in erudition; how can he really expect to make any converts in this way?). All the more so, then, among the least-well educated, from whom creationists recruit their ranks. The simpleton, faced with an alleged conflict between theology and science, might be tempted to reject science altogether, but in point of fact this stance is worse than that of the atheist who rejects theology for the same reason, far worse, as we will see in a moment. The atheist, at least, supposes himself to be upholding the demands of reason. From a proper theological perspective, the God of the theistic tradition is reasonable; or, to put it more precisely, is reason itself (Logos, the appellation that John the evangelist supplies to the Son of God in the prologue to his gospel, John 1:1). The great tradition in the Christian West has always taught that God creates the world according to constant laws of nature, and, indeed, this conviction played no little role in the historical rise of science during the transition from the middle ages to the early modern period; the presumption in favor of science, therefore, is so great that to overturn it is, in truth, to cease to be a believer in God. To be a creationist in our day, consequently, is not only counterproductive to the cause of religion, it is verily to deny God himself. It speaks volumes to the parlous conditions into which education has fallen in our modern times that an elementary point such as this is not widely appreciated; it should, after all, be the merest commonplace!

Back from our theological excursus to Knoll’s epilogue. He concludes with a reflection on how, in the Anthropocene, modern science—or, what would be more accurate, modern technology—may justify, at last, man’s claim to be made in the image of God and with an appeal to us to make responsible use of our unprecedented role as planetary stewards, into which, like it or not, we have unwittingly been thrust.
Profile Image for Donato Colangelo.
104 reviews6 followers
February 11, 2021
One requires to be strongly interested in the subject and willing to study some chemistry-related topics to understand the topics discussed herein, and how they are related among each other. I have rated the book as if I read it the year it was published. Though quite few years have passed since its publication, the book is still valuable today, since it presents a lenghty, rich, detailed discussion about hypothesis, theories and related flaws. It’s the way each element is discussed and put into context that makes this book enjoyable today. However, as the author states, not much has changed in the field since the first edition was published. This makes the book twice as valuable.
Good science books usually show a rich reference section, and “Life on a Young Planet” is such a book. Perhaps no one will search and read any of those papers, but the quality of the opera can be tested by putting Prof. Knoll’s conclusions to the test in this way. This is what science is supposed to be. In a book that tries to convey a picture of life in stark contrast with the story told in the so-called Holy Books, this element is vital. It is actually vital in the scientific world of debates, of which the early-life paleontological world is filled. In addition, I greatly appreciated the good number of pictures that help to give a look at rocks, fossils and digital reconstructions.
It is highly informative, that’s for sure. My only hope is that Prof. Knoll will write another such book in the years to come - or, that he updates for the second time this one.
Profile Image for Fred Dameron.
509 reviews8 followers
November 9, 2017
This book gives me more hope for earths future. I don't mean as far as humankind currently committing our own extinction is concerned; I mean that after we kill ourselves off in a purple algae world the recovery time will be, "A mere tick of the geological clock."

Let me explain.

It took around 3,000,000,000 years for the first chemicals to start joining together and forming microscopic life. That life was living in a sulfide/sulfate world. We can't live in a sulfide/sulfate world but purple algae can and did in huge, 100,000 of km across mats. This book explores these mats or what is left of them from Svalbard to Central Siberia. What was found was also small colonies of green algae in parts of these mats in the upper levels of these mats as the rock become younger. Since the current world is an Oxygen world those mats of green algae will be larger. The remnants of what we as humans leave the future. Green Algae mats in large quantities is our legacy. This will mean a quicker recovery time to get to another Cambrian explosion. After Cambrian part duex all we need is another 650,000,000 years and "Mankind" or if you prefer "Hominids" are back on top. This is where we need to look.

What message can we leave those "Hominids" of the future? Maybe they aren't hominids but some form of intelligent life, but still what message can we leave them? I would suggest that we deflesh and engrave in binary, a warning to these future intelligent beings, a warning. The warning should be "If you are reading this you have invented computing devices. If so you are probably burning carbon. The release of CO2 into our atmosphere led to our extinction. Save your selves and stop." They may not but if they keep the skeletons we bury now and bury their own. Assuming that eight to ten billon years until our sun explodes is correct. Earthlings have ten times to do this before our sun explodes and it no longer matters. If we don't leave a message for the future in a thousand years or so the last human will look on the last day and die from lack of oxygen and in 750,000,000 years another intelligent being will do the same. Intelligent humans aren't that smart. Hopefully we can help a future generation of intelligent beings save themselves.

This is a great science work and a readable piece on our early life. This early life will be repeated if we don't go to a renewable world. To find out about that future world look to the past and this book goes to that time before the Cambrian when life was microscopic, 10 nanometers, and purple. Great read.
Profile Image for Chris Farrell.
47 reviews4 followers
July 17, 2015
This book is a totally fascinating, if often impenetrable, review of the recent science of the early life and ecology of Earth. Chemistry was my science of choice in college, but I hadn't really kept up in the interim, I found the more recent advances in our understanding of how early single-celled life developed and evolved and created the conditions for more complex life by modifying the atmosphere engrossing. Other interesting topics include how periodic extinction events may have cleared the way for subsequent explosions and how radically different the climate was in the past (including theories that may have had Earth as a virtual snowball for a time).

Unfortunately, the writing and style is frequently impenetrable - I haven't had to work this hard on a book in a long time, and I'm glad I remembered a fair amount of my university biology and biochemistry. The author just assumes you understand things like the Krebs Cycle, Golgi apparatus, mitochondria, carbon and nitrogen fixing, respiration, and so on, as he talks about them without explanation. The narrative structure of the book jumps around a lot without explanation and while chapters focus on individual topics, they lack coherence and are often just a scattershot of recent science. Compared to the really great science writing of Brian Greene, Neil deGrasse Tyson, Mary Roach, and others, this is a mess.

Despite the difficulties, I enjoyed plowing through this. But I have to believe there is a better-written, more accessible book on this topic out there somewhere.
117 reviews
March 6, 2022
I've read a LOT of books about natural history, yet this is the first time I've read a book that describes the fossils that represented the three billion year gap between the origin of life on earth (the Proterozoic Era) and the beginning of the Paleozoic Era 541 million years ago.

If you were a time traveler visiting the earth during this period, you would've found yourself in a very boring world known as the "Snowball Earth" because that's what it would've looked like from space. The geologic evidence (from ancient glacier activity) suggests that two ice ages occurred during this period, and what life remained would've been warmed by hydrothermal vents (volcanic fissures) below the ice.

Yet I was surprised to learn that paleontologists discovered so many fossilized microscopic remains of single-celled organisms that thrived during this period, called eukaryotic, prokaryotic, and archae bacteria. Since fossilization is an extremely rare event, how did so much bacteria endure preservation?

I listened to this on audiobook, and although the first third of this book went way over my head, the last two thirds were quite easy to understand, and I intend to listen to it again.
Profile Image for Martin Oetiker.
8 reviews2 followers
March 16, 2016
This is a beautifully written, well argued account of the history of life on Earth from earliest signs of biochemical evolution 3.8 Bya to the Cambrian explosion of multicellular organisms 550Mya, by one of the leading experts in this field. It includes first hand details of the fieldwork and laboratory analyses carried out by himself and many others, and the evidence painstakingly gleaned, that underpin the latest theories in evolutionary sciences. It covers all the major innovations of life including the first pre-biotic molecules, the formation of cell membranes, various prokaryotic metabolic strategies, symbiosis and the origins of photosynthesis, leading to eukaryotic cells sexual reproduction and finally the creation of the first multicellular organisms. In addition it stresses the complex interplay between biology, geology and environment such as plate tectonics and global glaciations in stimulating evolutionary innovation. Andy Knoll is an excellent communicator able to present complex facts and ideas in an exciting and engaging way. Highly recommended.
13 reviews
July 31, 2020
An outstanding book, probably the best science book I have read in years!! Dr Knoll is an excellent author with a broad knowledge spanning both Geology, and Biology as well as a firm grounding in the Liberal Arts. I loved the highlights he drew from literary history to make his points more poignant.

I had taken Historical Geology in the 70's and the Precambrian was largely glossed over even though in Northern Wisconsin we were close to the Precambrian deposits of Northern Minnesota. To this day I had no idea of the recent developments that have shed light on these fascinating rocks. Thank you to Dr Knoll for informing me and through his inspiring writing encouraging me to further study this fascinating topic!
Profile Image for Dave Malone.
Author 20 books14 followers
February 28, 2023
I found this book listed as a top volume to read about the history of the beginning of the earth / life on our planet. I was very pleased. It's a great read, fascinating, and very well written. He has a great writing style and a quick sense of humor to get across his points about paleontology. As other reviewers have noted, be aware this is about life on the planet when it was just bacteria--there isn't much talk of animals, but that was fine with me--I wanted to know about the earliest of origins, befre humanoids. :) I felt like this was a solid read for my self-guided education on the history of the earth.
Profile Image for Elentarri.
1,497 reviews11 followers
May 2, 2019
This book is all about discovering what life was like on the early earth - the first three billion years of evolution on earth (i.e. mostly precambrian). That means the vast majority of this book is about rocks, microbes and fossil microbes - with a bit of chemistry, earth science and comparative evolutionary biology to flesh things out. Knoll has a knack for writing understandable science and clearly explaining why scientists think what they think about early life and what evidence there is support or oppose a specific hypothesis. A beautifully written book with numerous explanatory diagrams, B&W photographs and a section of colour plates.
Profile Image for Liene.
35 reviews2 followers
November 11, 2019
It was definitely visible that the author has a vast knowledge in his field, and it was very interesting to read how he dissected different lines of arguments to draw conclusions. You need to have some geology vocabulary to have an easy-read, but that also helps to dive deeper into the topics and show a more nuanced discussion. Nevertheless, at some points it felt like I was reading something alond the lines of ''Dear Diary,....'' in the parts where he introduced his field work, which felt a bit boring and not as well written.
Profile Image for Batsheva.
347 reviews20 followers
December 22, 2016
A little slow going at first, but a fascinating look at the study of ancient microfossils. The majority of the time life was on planet Earth (~3 billion years), it existed predominantly as single-celled organisms. We owe our habitable planet (and its established biogeochemical cycles) to the metabolism of tiny living beings from long, long ago.
Profile Image for Marc Oliver.
Author 1 book4 followers
May 18, 2017
A fascinating book about the first three billion years of life on Planet Earth. It’s a story well told and beautifully written, with lots of information, and some really entertaining anecdotes. Knoll knows how to present the relatively uneventful evolution of unicellular life interesting and with style.
Profile Image for Nick Winlund.
25 reviews7 followers
May 21, 2017
An exceptional overview of the paleontological, biochemical and geochemical processes and mechanisms that made up our early Earth. The book goes into sediments, metamorphic rocks, fossils, ocean chemistry and atmospheric processes. Concise and well written!
1 review
September 28, 2019
Fascinating book that starts when earth cools from its molten state and stops at the Cambrian Explosion . Life was here long before that . Needs a little basic understanding of middle school science to get through
68 reviews26 followers
April 2, 2022
I think I read an older edition, so I can't speak for whatever the current preface might say, but I found it a quite easy read and enjoyed it a fair bit. I had wanted a book that went into details I wasn't already familiar with, and this gave me that. In particular, the details of the oxygen levels and their impact on animal evolution was something I had been curious about. I also liked the discussion of microbe evolution, although I was already familiar with things like some organisms acquiring photosynthesis by swallowing other organisms with photosynthesis who had swallowed other organisms with photosynthesis like some sort of living Russian doll. In my opinion, people who are only interested in animals because they are like us are boring and unimaginative.

As noted by another reviewer, the fast developments in the field have made this slightly outdated. We now know a lot more about Ediacarian fauna and what they were. Progress has been made on the question of making RNA nucleotides, as well:

A very minor critique is that at the very end the author suggests religion and science don't have to be at odds. That might be true for the set of facts that science as-is currently suggests, being that there is no currently published accepted scientific theory of the origin of the big bang, but as a philosophy religion and science are inherently at odds (one being to take things on faith, the other being to test things via experiment and prediction), and it seems a bit presumptuous to assume that science will never make a theory guessing about the origins of the universe which it will then wish to decide by scientific testing and not via faith. When/if that happens, science and religion will have a fundamental clash the likes we have never seen before.
I would hope people would resolve it in a kind and understanding manner of one another, but people have repeatedly disappointed me.
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