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Rare Earth: Why Complex Life Is Uncommon in the Universe
This book marshals data from geology, astronomy, and biology to put forth a radical hypothesis: while primitive organisms such as microbes are very likely abundant across the galaxies, advanced life, depending as it does on a myriad of special circumstances, is altogether another story, In a thought-provoking departure from the widely held view that there must be countless civilizations of intelligent beings out there, Ward and Brownlee suggest that multicellular life-forms, let alone life-forms with whom we'd be able to communicate, must be exceedingly rare.
334 pages, Paperback
First published January 1, 1999
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About the author
Peter D. Ward
29 books104 followersPeter Douglas Ward is an American paleontologist and professor of Biology and of Earth and Space Sciences at the University of Washington, Seattle. He has written popular numerous science works for a general audience and is also an adviser to the Microbes Mind Forum.
His parents, Joseph and Ruth Ward, moved to Seattle following World War II. Ward grew up in the Seward Park neighborhood of Seattle, attending Franklin High School, and he spent time during summers at a family summer cabin on Orcas Island.
Ward's academic career has included teaching posts and professional connections with Ohio State University, the NASA Astrobiology Institute, the University of California, McMaster University (where he received his PhD in 1976), and the California Institute of Technology. He was elected as a Fellow of the California Academy of Sciences in 1984.
Ward specializes in the Cretaceous–Paleogene extinction event, the Permian–Triassic extinction event, and mass extinctions generally. He has published books on biodiversity and the fossil record. His 1992 book On Methuselah's Trail received a Golden Trilobite Award from the Paleontological Society as the best popular science book of the year. Ward also serves as an adjunct professor of zoology and astronomy.
His book The End of Evolution was published in 1994. In it, he discussed in three parts, each about an extinction event on earth.
Ward is co-author, along with astronomer Donald Brownlee, of the best-selling Rare Earth: Why Complex Life Is Uncommon in the Universe, published in 2000. In that work, the authors suggest that the universe is fundamentally hostile to advanced life, and that, while simple life might be abundant, the likelihood of widespread lifeforms as advanced as those on Earth is marginal. In 2001, his book Future Evolution was published, featuring illustrations by artist Alexis Rockman.
Ward and Brownlee are also co-authors of the book The Life and Death of Planet Earth: How the New Science of Astrobiology Charts the Ultimate Fate of the World, which discusses the Earth's future and eventual demise as it is ultimately destroyed by a warming and expanding Sun.
According to Ward's 2007 book, Under a Green Sky, all but one of the major mass extinction events in history have been brought on by climate change—the same global warming that occurs today. The author argues that events in the past can give valuable information about the future of our planet. Reviewer Doug Brown goes further, stating "this is how the world ends." Scientists at the Universities of York and Leeds also warn that the fossil record supports evidence of impending mass extinction.
His parents, Joseph and Ruth Ward, moved to Seattle following World War II. Ward grew up in the Seward Park neighborhood of Seattle, attending Franklin High School, and he spent time during summers at a family summer cabin on Orcas Island.
Ward's academic career has included teaching posts and professional connections with Ohio State University, the NASA Astrobiology Institute, the University of California, McMaster University (where he received his PhD in 1976), and the California Institute of Technology. He was elected as a Fellow of the California Academy of Sciences in 1984.
Ward specializes in the Cretaceous–Paleogene extinction event, the Permian–Triassic extinction event, and mass extinctions generally. He has published books on biodiversity and the fossil record. His 1992 book On Methuselah's Trail received a Golden Trilobite Award from the Paleontological Society as the best popular science book of the year. Ward also serves as an adjunct professor of zoology and astronomy.
His book The End of Evolution was published in 1994. In it, he discussed in three parts, each about an extinction event on earth.
Ward is co-author, along with astronomer Donald Brownlee, of the best-selling Rare Earth: Why Complex Life Is Uncommon in the Universe, published in 2000. In that work, the authors suggest that the universe is fundamentally hostile to advanced life, and that, while simple life might be abundant, the likelihood of widespread lifeforms as advanced as those on Earth is marginal. In 2001, his book Future Evolution was published, featuring illustrations by artist Alexis Rockman.
Ward and Brownlee are also co-authors of the book The Life and Death of Planet Earth: How the New Science of Astrobiology Charts the Ultimate Fate of the World, which discusses the Earth's future and eventual demise as it is ultimately destroyed by a warming and expanding Sun.
According to Ward's 2007 book, Under a Green Sky, all but one of the major mass extinction events in history have been brought on by climate change—the same global warming that occurs today. The author argues that events in the past can give valuable information about the future of our planet. Reviewer Doug Brown goes further, stating "this is how the world ends." Scientists at the Universities of York and Leeds also warn that the fossil record supports evidence of impending mass extinction.
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September 2, 2012
An intriguing book, it was written by two scientists - Ward, a noted paleontologist, and Brownlee, an astronomer - who sought to challenge the concept, rather widespread actually, that complex, even intelligent life, is probably common in the universe. They felt that some of this bias in believing this stems from wishful thinking, no doubt fueled by science fiction, but also by science itself, notably the Drake Equation, put forth by astronomers Frank Drake and Carl Sagan. This equation, one designed to estimate the number of advanced civilizations present in our galaxy, was based on educated guesses on how many planets there were in our galaxy, how many of those might harbor life, and of those what percentage advanced to become homes of civilized life forms. Using the best estimates at the time, Drake and Sagan in 1974 postulated that a million civilizations may exist in the Milky Way galaxy alone, and as our galaxy is but one of hundreds of millions of galaxies, according to them the number of intelligent alien species must be staggering.Of course, as followers of this science, even at a popular level like me, know that many of these planets found so far are hellish nighmare worlds....
Ward and Brownlee, not fans of the Drake Equation, put forth instead the Rare Earth Hypothesis. In essence, they believe that microbial life is very common in the universe, perhaps more common than even Drake and Sagan anticipated, while complex life - animals and higher plants - is quitem, quite rare.
As far as the microbial, single-celled life, they feel the evidence for that exisiting is good; life apparently appeared very early on in our planet's history, while things were still pretty hairy (no oxygen in the atmosphere, the heavy bombardment phase not quite over). Throw in all the extremophiles that have been found in ice, solid rock, boiling water, high salt environs and they feel the notion that something is out there is a solid one indeed.
While many planets may team with their equivalents of bacteria or even protozoa, the conditions that formed larger organisms, plants and animals, may have been, in their words, "rare if not unique." Too many "low probability" events had to occur for such life to even have a chance (or survive once here).
One of the books strengths was not just discussing such concepts as a planet of just the right size with just the right gravity being just right distance from just the right star. That, I knew, I and suspect most who would read this book. What I did not know was that there are galactic habitable zones. There are bad neighborhoods so to speak in a galaxy or bad types of galaxies (such as globular clusters, elliptical galaxies, or a small galaxy, as most if not all stars in these formations (or the wrong parts of a galaxy that is otherwise probably ok) are too metal-poor and often are too hot for life on inner planets. In systems low in metals (elements other than hydrogen and helium, which covers just about everything else), there wouldn't be enough solid matter to form a planet the size of Earth and even if one formed it would lack the metals needed to produce either magnetic fields or the internal heat sources to drive plate tectonics, two vital things to sustaining life once it evolves.
Even in suitable galaxies an Earth-type planet couldn't exist in its center, as that is a region with multiple energetic processes that could sterilize a planet; the high density of stars in the center make the danger of supernovae significant (our sun and planet are protected only by the relative scarcity of stars around us). Other stellar neighbors, such as neutron stars called magnetars, are considerably more common in the center (which can emit vast amounts of lethal X-rays and gamma rays). The galactic edge is not any better; Earth would never have appeared there as that region is too metal poor.
Other factors the authors emphasize include plate tectonics (check, I had heard that one before, but they make an excellent case of the many reasons why it is important), the importance of a Moon (again, heard that before but again, they do a good job of discussing just why it is important), and the importance of a stable gas giant in the system (something that looks like today as bit of an oddity given how many Hot Jupiters there are). On top of that, they discuss possibly unique events, such as Snowball Earth and the Cambrian Explosion.
This book won't give you hope that life is out there, that much is certain. It might make you though appreciate how unusual the Earth is. That it is, truly, perhaps, unique. The universe is probaly fascinating but also a lonely and dark place indeed.
Ward and Brownlee, not fans of the Drake Equation, put forth instead the Rare Earth Hypothesis. In essence, they believe that microbial life is very common in the universe, perhaps more common than even Drake and Sagan anticipated, while complex life - animals and higher plants - is quitem, quite rare.
As far as the microbial, single-celled life, they feel the evidence for that exisiting is good; life apparently appeared very early on in our planet's history, while things were still pretty hairy (no oxygen in the atmosphere, the heavy bombardment phase not quite over). Throw in all the extremophiles that have been found in ice, solid rock, boiling water, high salt environs and they feel the notion that something is out there is a solid one indeed.
While many planets may team with their equivalents of bacteria or even protozoa, the conditions that formed larger organisms, plants and animals, may have been, in their words, "rare if not unique." Too many "low probability" events had to occur for such life to even have a chance (or survive once here).
One of the books strengths was not just discussing such concepts as a planet of just the right size with just the right gravity being just right distance from just the right star. That, I knew, I and suspect most who would read this book. What I did not know was that there are galactic habitable zones. There are bad neighborhoods so to speak in a galaxy or bad types of galaxies (such as globular clusters, elliptical galaxies, or a small galaxy, as most if not all stars in these formations (or the wrong parts of a galaxy that is otherwise probably ok) are too metal-poor and often are too hot for life on inner planets. In systems low in metals (elements other than hydrogen and helium, which covers just about everything else), there wouldn't be enough solid matter to form a planet the size of Earth and even if one formed it would lack the metals needed to produce either magnetic fields or the internal heat sources to drive plate tectonics, two vital things to sustaining life once it evolves.
Even in suitable galaxies an Earth-type planet couldn't exist in its center, as that is a region with multiple energetic processes that could sterilize a planet; the high density of stars in the center make the danger of supernovae significant (our sun and planet are protected only by the relative scarcity of stars around us). Other stellar neighbors, such as neutron stars called magnetars, are considerably more common in the center (which can emit vast amounts of lethal X-rays and gamma rays). The galactic edge is not any better; Earth would never have appeared there as that region is too metal poor.
Other factors the authors emphasize include plate tectonics (check, I had heard that one before, but they make an excellent case of the many reasons why it is important), the importance of a Moon (again, heard that before but again, they do a good job of discussing just why it is important), and the importance of a stable gas giant in the system (something that looks like today as bit of an oddity given how many Hot Jupiters there are). On top of that, they discuss possibly unique events, such as Snowball Earth and the Cambrian Explosion.
This book won't give you hope that life is out there, that much is certain. It might make you though appreciate how unusual the Earth is. That it is, truly, perhaps, unique. The universe is probaly fascinating but also a lonely and dark place indeed.
February 9, 2017
Having read David Waltham’s Lucky Planet, there isn’t much in this older book which is new to me, even though he recommended it for further reading. It’s less up to date, of course, but that’s because it’s older — and at least it does acknowledge stuff like the Viking lander biological experiments, which Waltham did not. If you’re interested in the evidence that’s out there for the fact that our planet might be rare indeed in producing complex life, I’d recommend Rare Earth over Lucky Planet. The science is solid and thorough, and well explained.
My problem with all books like this is always going to be: we have a sample size of one. How can we extrapolate anything? Sure, we know that intelligent life like ourselves can’t exist in a solar system that doesn’t have the right kind of habitable zone. And yeah, we think carbon is the best possible atom to base biochemistry on. But we only think or know these things because that’s what we need, that’s what we can use, under the conditions in which we find ourselves observing. (In other words, it’s the weak anthropic principle.) None of the data presented convinces me that we can do more than guessing in the dark on this subject.
That’s not a reason not to be curious, of course, but it’s also not a reason to give up looking. Obviously, we won’t find anything if we don’t look. It doesn’t make Rare Earth less worth reading, but it does mean that I think readers should stay aware that Ward and Brownlee have made up their minds, and are presenting only the evidence supporting their case. I honestly don’t find either side convincing, though you, of course, may differ.
Originally posted here.
My problem with all books like this is always going to be: we have a sample size of one. How can we extrapolate anything? Sure, we know that intelligent life like ourselves can’t exist in a solar system that doesn’t have the right kind of habitable zone. And yeah, we think carbon is the best possible atom to base biochemistry on. But we only think or know these things because that’s what we need, that’s what we can use, under the conditions in which we find ourselves observing. (In other words, it’s the weak anthropic principle.) None of the data presented convinces me that we can do more than guessing in the dark on this subject.
That’s not a reason not to be curious, of course, but it’s also not a reason to give up looking. Obviously, we won’t find anything if we don’t look. It doesn’t make Rare Earth less worth reading, but it does mean that I think readers should stay aware that Ward and Brownlee have made up their minds, and are presenting only the evidence supporting their case. I honestly don’t find either side convincing, though you, of course, may differ.
Originally posted here.
September 21, 2023
I’ve been watching movies and shows and reading books about extraterrestrial life for as long as I can remember: Star Wars, Star Trek, Flash Gordon, Dune, the Hitchhiker’s Guide to the Galaxy, Battlestar Galactica, Buck Rogers in the 25th Century, and E.T., to name just a few. When I started reading Carl Sagan books as a teen, I was enthralled with the proposition that we inhabit a universe that is likely teeming with intelligent beings, some of which we might someday encounter and interact with! Based on the mind-boggling number of galaxies, stars, and planets in the visible universe, surely there must be many intelligent aliens out there, right? And maybe, just maybe, there are.
But on the other hand, this assumption may not be correct at all. The authors of Rare Earth lay out a strong, scientific case for the rarity of complex, intelligent life, based primarily on what we know about our little planet and the history of our Solar System. Given all of the factors that had to go our way for us to exist here now, we are some lucky-ass complex life forms, let me tell you.
Our universe is not very hospitable to life, with its exploding stars and galaxies, temperature extremes, violent impacts from comets, asteroids or other bodies, erupting volcanoes, or merely the lack of liquid water. It seems there are tiny niches where life can survive under very specific conditions, and then only while those conditions last. Frankly, we’ve been dodging bullets on this planet for a long time now.
The authors grant that life may be widespread throughout the universe, something comparable to the type of microbial, single-celled life that inhabited Earth for billions of years before complex life ever arose—pond scum, basically. But for complex life to form and evolve to the point of being able to question its own existence is a far more complicated and delicate affair.
This book covers a lot of ground in only 312 pages, touching on issues in cosmology, planetary science, geology, evolutionary biology, and chemistry. Of course, there is a great deal of speculation going on here due to lack of any proof of otherworldly life so far. But, if the authors’ conclusions are valid, we are very, very special indeed. Highly recommended.
But on the other hand, this assumption may not be correct at all. The authors of Rare Earth lay out a strong, scientific case for the rarity of complex, intelligent life, based primarily on what we know about our little planet and the history of our Solar System. Given all of the factors that had to go our way for us to exist here now, we are some lucky-ass complex life forms, let me tell you.
Our universe is not very hospitable to life, with its exploding stars and galaxies, temperature extremes, violent impacts from comets, asteroids or other bodies, erupting volcanoes, or merely the lack of liquid water. It seems there are tiny niches where life can survive under very specific conditions, and then only while those conditions last. Frankly, we’ve been dodging bullets on this planet for a long time now.
The authors grant that life may be widespread throughout the universe, something comparable to the type of microbial, single-celled life that inhabited Earth for billions of years before complex life ever arose—pond scum, basically. But for complex life to form and evolve to the point of being able to question its own existence is a far more complicated and delicate affair.
This book covers a lot of ground in only 312 pages, touching on issues in cosmology, planetary science, geology, evolutionary biology, and chemistry. Of course, there is a great deal of speculation going on here due to lack of any proof of otherworldly life so far. But, if the authors’ conclusions are valid, we are very, very special indeed. Highly recommended.
May 28, 2023
Peter D. Ward, Donald Brownlee – Rare Earth. Why Complex Life Is Uncommon in the Universe
Speechless, overwhelmed. It’s how I feel, subdued by the greatness of the universe. All that had occurred since the “big bang”, all that allowed life on earth, animal life and my own existence. Facing that magnificent achievement, I am compelled to act with anger against those that manifests an unacceptable indifference with life and the “miracle” of our own existence.
For long I suspect that life on earth had result from a long series of random events that scarcely could be repeated in the universe. A serendipity in all directions.
From my spot of observation, all that happened since the “big-bang”, 13,8 billion years ago seems like a miracle. It all appears to me as if something or somebody had guided and have a purpose that allows my reflection today. A teleonomic regulation.
In my observation it is easy to give the credits to a God, a creator, or to an intelligent universe like Fred Hoyle suggested, or yet to the “clever watchmaker” of William Paley, or to a programed universe of Miguel Ribeiro. It’s easy to give those credits, but it’s only an error of perspective. From my place, it seems a miracle, but an observer at the “Big-Bang”, our endpoint is only one possibility. Others could happen, equally possible, equally miraculous from their point of view.
Since the beginning, all that happened in the universe or all that is to come, results from the laws of physics or is depends on chance and could or could not had happened. We are the result of all these events. With other laws or other chances, and the result would certainly be another. We are the result of those laws and random events, and not the result of a difficult path. We are the result of a long series of events, events that appears like a chain of incidents some with causality, others perfectly random.
In the present book, Peter Ward and Donald Brownlee present good examples of that narrow path. A supernova, an event that as an label of extermination of all life, although his destructive potential is probably indispensable to more complex life. Without supernovas, radioactive elements like uranium would not be synthesized, or some heavy elements would not be there in enough quantities. Without these elements planets would not have a core, and without that core we would not have energy production for the central worming, tectonic plates movement, protection against cosmic radiation, avoiding of atmosphere loosing and the conditions for stable or complex life.
We are supernova in origins. And like Lee Smolin suggests, we exist in this universe with the physical laws that we know. Other universes could exist with other laws or constants. In some of them life would not be possible, in other it would be different.
In this book, Peter Ward e Donald Brownlee shows us why in our universe the “Mediocrity” principle can induced us a false picture of frequency of planets friendly to life, open to animal life.
Frank Drake e Carl Sagan in the second half of the 20th century had calculated the possibility of worlds (planets) with earth characteristics and with the possibility of animal life. They had estimated this possibility between 1% and 0,0001% of all existent planets.
After reading this book we must agree that these estimates are surely over weighted. And to do this kind of exercise, we must first define to what forms of life we are referring.
With the present knowledge we don’t know how life had begun. We don’t have the details, and the tricky are in the minutia, but we know with certitude that life had begun 3.8 to 4 billion years ago. Several emergences had occurred from our Lost Universal Common Ancestor (LUCA), and according to tree of life of Carl Woese, to the first bacteria and archaea, to the first eukaryote cell some 1,5 billion after, to the first protozoa 500 million years forward, first metazoan 700 million years later, and the cambric explosion in the last 500 million years. As life becomes complex it narrows the window of environment requirements and become more demanding for long periods of stability and complexity emergence.
In these 4 billion of years of evolution, events happened and only with great difficulty they could be replied. From these I think that the jump between inorganic and organic chemistry and between the latest and the emergence of the first living entity were the first “gordian knot”, but others like the acquisitions of mitochondria, nucleus, or the emergence of organisms with cells with different functions cooperating, and the emergence of the cambric period where points of evolution that are certainly hard to be repeated.
With this evolution “bottleneck” hazard in mind, it is logical to assume that the more complex life his, the more delicate are the survival requirements that it needs and lower the probability of this experience “earth experience” to be repeated or reproducible.
Anyway, the rule of thumb must be, more complex life is, more demanding is and more requirements are needed.
And what which was these “cosmic” requirements:
A planet must coalesced out of debris from previous comic events; In a position in the galaxy highly appropriated for the development of life; around a star appropriate; a star rich in metal; a star away from the spiral region of the galaxy; a star moving very slowly, not in the center of the galaxy, not in a metal-poor galaxy, not in a globular cluster, not near a gama-ray source, not in a multi-star system, not even a binary one, near a pulsar or a supernova; a stars that is either not too small or too large.
A planet that is orbiting a star in the habitable zone, a star that emits constant energy for a long period, that was hit at the right time, that is protected by “Jovian” planets, and during the last period of evolution was for a period of 600.000 years not hit by major events with asteroids and comets.
A planet that avoids the tidal effect of the sun; that has a regular orbit at a constant distance from the sun; that have the right tilt; that have a large moon that regulates months, tides, stabilizes earth spin tilt; a moon that during it’s accretion had supply earth with the right constituents for the core and the biological building; a planet after initial accretion had stopped the heavy bombardment; and was in a galactical region without risk for cosmic cataclysms.
A planet with a core rich in uranium, potassium and thorium for internal heating, and iron and nickel for magnetic field generation; a planet with radioactivity in its core and whose decay warms the planet; a generation of heat and energy that moves the tectonic plates; whose movement give rise to volcanic activity and CO2 reposition; to the longitudinal distribution of continents; the recycling of inorganic elements; the limestone formation and the control of CO2 levels; and the “CO2 – silicate cycle”, responsible for having CO2 at 350 ppm, a level that is responsible for 40ºC of temperature;
A planet that during its accretion period achieved water in liquid state, in quantities that covers the planet but allows the presence of islands and continents; a planet with regular temperatures that allows liquid water for 4 billion years; a planet rich in the rights building materials, (oxygen, Ca, Fe, other metals, carbon and nitrogen; a planet that controls CO2 levels through volcanic eruptions and limestone formation; a planet that has carbon levels and others life forming elements; continents with dimensions appropriated for animal life evolution; appropriate atmosphere; long temperature and physical conditions allowing stability and animal evolution; continents with a latitude disposition most appropriate to life complexity, diversion and resilience.
A planet that was formed by accretion, several impacts; a major one with theia, a collision essential for materials need for the core; a core that generates a magnetic field and prevents cosmic radiations and atmosphere loosing; a collision that also made disposable enough materials for the moon formation; a moon with the right dimensions and at the right distance.
A very, very lucky and blessed planet, that if we do not believe in some sort of teleonomic guidance, we must assume that we are a rarity, a rarity that we have the ultimate duty of defend and protect.
The book of Peter D. Ward, Donald Brownlee helps us to understand the exquisite of our planet and the manifestations of the wonderful life that surrounds us.
Speechless, overwhelmed. It’s how I feel, subdued by the greatness of the universe. All that had occurred since the “big bang”, all that allowed life on earth, animal life and my own existence. Facing that magnificent achievement, I am compelled to act with anger against those that manifests an unacceptable indifference with life and the “miracle” of our own existence.
For long I suspect that life on earth had result from a long series of random events that scarcely could be repeated in the universe. A serendipity in all directions.
From my spot of observation, all that happened since the “big-bang”, 13,8 billion years ago seems like a miracle. It all appears to me as if something or somebody had guided and have a purpose that allows my reflection today. A teleonomic regulation.
In my observation it is easy to give the credits to a God, a creator, or to an intelligent universe like Fred Hoyle suggested, or yet to the “clever watchmaker” of William Paley, or to a programed universe of Miguel Ribeiro. It’s easy to give those credits, but it’s only an error of perspective. From my place, it seems a miracle, but an observer at the “Big-Bang”, our endpoint is only one possibility. Others could happen, equally possible, equally miraculous from their point of view.
Since the beginning, all that happened in the universe or all that is to come, results from the laws of physics or is depends on chance and could or could not had happened. We are the result of all these events. With other laws or other chances, and the result would certainly be another. We are the result of those laws and random events, and not the result of a difficult path. We are the result of a long series of events, events that appears like a chain of incidents some with causality, others perfectly random.
In the present book, Peter Ward and Donald Brownlee present good examples of that narrow path. A supernova, an event that as an label of extermination of all life, although his destructive potential is probably indispensable to more complex life. Without supernovas, radioactive elements like uranium would not be synthesized, or some heavy elements would not be there in enough quantities. Without these elements planets would not have a core, and without that core we would not have energy production for the central worming, tectonic plates movement, protection against cosmic radiation, avoiding of atmosphere loosing and the conditions for stable or complex life.
We are supernova in origins. And like Lee Smolin suggests, we exist in this universe with the physical laws that we know. Other universes could exist with other laws or constants. In some of them life would not be possible, in other it would be different.
In this book, Peter Ward e Donald Brownlee shows us why in our universe the “Mediocrity” principle can induced us a false picture of frequency of planets friendly to life, open to animal life.
Frank Drake e Carl Sagan in the second half of the 20th century had calculated the possibility of worlds (planets) with earth characteristics and with the possibility of animal life. They had estimated this possibility between 1% and 0,0001% of all existent planets.
After reading this book we must agree that these estimates are surely over weighted. And to do this kind of exercise, we must first define to what forms of life we are referring.
With the present knowledge we don’t know how life had begun. We don’t have the details, and the tricky are in the minutia, but we know with certitude that life had begun 3.8 to 4 billion years ago. Several emergences had occurred from our Lost Universal Common Ancestor (LUCA), and according to tree of life of Carl Woese, to the first bacteria and archaea, to the first eukaryote cell some 1,5 billion after, to the first protozoa 500 million years forward, first metazoan 700 million years later, and the cambric explosion in the last 500 million years. As life becomes complex it narrows the window of environment requirements and become more demanding for long periods of stability and complexity emergence.
In these 4 billion of years of evolution, events happened and only with great difficulty they could be replied. From these I think that the jump between inorganic and organic chemistry and between the latest and the emergence of the first living entity were the first “gordian knot”, but others like the acquisitions of mitochondria, nucleus, or the emergence of organisms with cells with different functions cooperating, and the emergence of the cambric period where points of evolution that are certainly hard to be repeated.
With this evolution “bottleneck” hazard in mind, it is logical to assume that the more complex life his, the more delicate are the survival requirements that it needs and lower the probability of this experience “earth experience” to be repeated or reproducible.
Anyway, the rule of thumb must be, more complex life is, more demanding is and more requirements are needed.
And what which was these “cosmic” requirements:
A planet must coalesced out of debris from previous comic events; In a position in the galaxy highly appropriated for the development of life; around a star appropriate; a star rich in metal; a star away from the spiral region of the galaxy; a star moving very slowly, not in the center of the galaxy, not in a metal-poor galaxy, not in a globular cluster, not near a gama-ray source, not in a multi-star system, not even a binary one, near a pulsar or a supernova; a stars that is either not too small or too large.
A planet that is orbiting a star in the habitable zone, a star that emits constant energy for a long period, that was hit at the right time, that is protected by “Jovian” planets, and during the last period of evolution was for a period of 600.000 years not hit by major events with asteroids and comets.
A planet that avoids the tidal effect of the sun; that has a regular orbit at a constant distance from the sun; that have the right tilt; that have a large moon that regulates months, tides, stabilizes earth spin tilt; a moon that during it’s accretion had supply earth with the right constituents for the core and the biological building; a planet after initial accretion had stopped the heavy bombardment; and was in a galactical region without risk for cosmic cataclysms.
A planet with a core rich in uranium, potassium and thorium for internal heating, and iron and nickel for magnetic field generation; a planet with radioactivity in its core and whose decay warms the planet; a generation of heat and energy that moves the tectonic plates; whose movement give rise to volcanic activity and CO2 reposition; to the longitudinal distribution of continents; the recycling of inorganic elements; the limestone formation and the control of CO2 levels; and the “CO2 – silicate cycle”, responsible for having CO2 at 350 ppm, a level that is responsible for 40ºC of temperature;
A planet that during its accretion period achieved water in liquid state, in quantities that covers the planet but allows the presence of islands and continents; a planet with regular temperatures that allows liquid water for 4 billion years; a planet rich in the rights building materials, (oxygen, Ca, Fe, other metals, carbon and nitrogen; a planet that controls CO2 levels through volcanic eruptions and limestone formation; a planet that has carbon levels and others life forming elements; continents with dimensions appropriated for animal life evolution; appropriate atmosphere; long temperature and physical conditions allowing stability and animal evolution; continents with a latitude disposition most appropriate to life complexity, diversion and resilience.
A planet that was formed by accretion, several impacts; a major one with theia, a collision essential for materials need for the core; a core that generates a magnetic field and prevents cosmic radiations and atmosphere loosing; a collision that also made disposable enough materials for the moon formation; a moon with the right dimensions and at the right distance.
A very, very lucky and blessed planet, that if we do not believe in some sort of teleonomic guidance, we must assume that we are a rarity, a rarity that we have the ultimate duty of defend and protect.
The book of Peter D. Ward, Donald Brownlee helps us to understand the exquisite of our planet and the manifestations of the wonderful life that surrounds us.
March 23, 2010
This is a rare book, a book on science which is informative and inspiring without really trying to be. If we destroy 5% of species on earth, we may be doing a lot more than just that, we may be destroying 5% of the species in this sector of the galaxy.
The authors explain a wide variety of different topics in several different disciplines in a non-dogmatic way, from astronomy and physics to biology and geography, just laying out what we think we know and how it relates to the formation of life on earth. This is a book in which I learned not just one new thing, but a whole bunch of different things that all relate to the question of the origin of complex life. (Simple life forms, they argue, may be quite common in the universe.) This book is sufficiently good so that it doesn't matter that much to me if the book is true (although it is quite convincing); I learned so much that the "refutation," if it comes, will have to build on what I learned in this book.
A lot of the book is taken up with the single case of life that we know the best -- life on earth. There is a lot that goes into supporting intelligent life on earth besides just life itself. There's plate tectonics, the balance of water and continents, mass extinctions, a unique moon that stabilizes the tilt of the earth, Jupiter, and other things. And we don't really know what's really behind the Cambrian explosion, or the development of higher life forms (plants and animals, for example) from the microbes. So this really was a fascinating book.
The authors explain a wide variety of different topics in several different disciplines in a non-dogmatic way, from astronomy and physics to biology and geography, just laying out what we think we know and how it relates to the formation of life on earth. This is a book in which I learned not just one new thing, but a whole bunch of different things that all relate to the question of the origin of complex life. (Simple life forms, they argue, may be quite common in the universe.) This book is sufficiently good so that it doesn't matter that much to me if the book is true (although it is quite convincing); I learned so much that the "refutation," if it comes, will have to build on what I learned in this book.
A lot of the book is taken up with the single case of life that we know the best -- life on earth. There is a lot that goes into supporting intelligent life on earth besides just life itself. There's plate tectonics, the balance of water and continents, mass extinctions, a unique moon that stabilizes the tilt of the earth, Jupiter, and other things. And we don't really know what's really behind the Cambrian explosion, or the development of higher life forms (plants and animals, for example) from the microbes. So this really was a fascinating book.
April 1, 2008
Note the subtitle of the book is "Why COMPLEX Life Is Uncommon in the Universe". The authors conclude that simple life is likely widespread throughout the universe--and was very likely seeded here from space. The SETI-types rebutted Rare Earth with their own take, hilariously titled, "Life Everywhere." After all, if your funding was based on the belief that E.T. is out there just around the next sun, you'd be upset by this book too. But once you've read Rare Earth you'll understand why Newsday said, "…[a book that] has hit the world of astrobiologists like a killer asteriod…".
April 3, 2016
There are probably millions of other planets in the galaxy with bacteria, but according to this book, very very few with civilization or even animals. The conditions that enabled life to develop may be very widespread in the universe, but Earth has been unusually stable for a long time due to conditions that are extremely unusual. The Sun is brighter than 95% of stars, giving it a bigger Goldilocks zone. The solar system is much richer in heavy elements than average, making rocky planets possible. Jupiter stabilizes the orbits of the inner planets - if there were another giant, or if Jupiter's orbit were elliptical, it would be very different. The Moon (probably extremely rare) keeps Earth's axis perpendicular to the orbit, important for stable climate. Earth is the right size and has the right composition to support plate tectonics, necessary to create continents, which are needed not only to provide land but to fertilize the oceans and enable complex organisms. We are far enough from the galactic center to avoid frequent nearby supernovas and other cosmic hiccups that would sterilize the planet. For all these reasons and more, it has been possible for complex life, i.e., eukaryotes including animals and plants, to evolve. The book doesn't even treat the question of how likely it is, given animals, that you will get a human-level intelligence. Very interesting book.
October 3, 2014
A difficult book to review. For starters, the book is basically a catalogue of all the factors that probably or possibly contributed to a planet where complex animal life could evolve. There are plenty of ideas here that I'd never come across before: that life probably wouldn't exist on Earth without plate tectonics, or without the existence of the Moon and Jupiter. These were great ideas! I'm going to include these ideas in my lectures! These ideas are amazing and fascinating!
But jeez, the actual text was boring, boring, boring. It was such a slog, such a chore to drag myself through the actual words that I could hardly believe it. It wasn't that it was bad; it's just that it was so dry. I'd sit down to read every night, and think, "Maybe I'll read a section of The Logic of Scientific Discovery first, just to put off Rare Earth for another couple of minutes". When, ten pages from the end (I was counting), the authors began a section with "Let us recap why we think the Earth is rare.", I almost screamed.
So I'm giving it two stars. I think you should read it, for the ideas, but I don't envy you the task of actually looking at the pages.
But jeez, the actual text was boring, boring, boring. It was such a slog, such a chore to drag myself through the actual words that I could hardly believe it. It wasn't that it was bad; it's just that it was so dry. I'd sit down to read every night, and think, "Maybe I'll read a section of The Logic of Scientific Discovery first, just to put off Rare Earth for another couple of minutes". When, ten pages from the end (I was counting), the authors began a section with "Let us recap why we think the Earth is rare.", I almost screamed.
So I'm giving it two stars. I think you should read it, for the ideas, but I don't envy you the task of actually looking at the pages.
June 21, 2011
One of the most popular themes in science fiction is the prevalence of alien intelligent life in the Universe. While the supposed real-life abductions and UFO sightings may be silly, the scientific consensus has been that intelligent life is common in the Universe. Peter D. Ward and Donald Brownlee support the idea that simple life forms are common in the Universe, but contend in Rare Earth that any type of complex, multi-cellular animal life is extremely rare. Their book covers the “Rare Earth Hypothesis” which explores the difficulties that evolution overcame to reach today’s complexity, as well as the special conditions of the Earth, Moon, Sun, and Solar System that produced the extended period of stability needed to foster complex life and prevent sterilization of the entire planet.
I am nowhere near an expert on this topic, but as a scientist I found this book worthy of a review. I highly recommend it for its clear qualitative explanations of complicated scientific topics and its relatively neutral presentation of both sides of the more controversial topics. While readers may have qualms with at least some portion of the Rare Earth hypothesis, most will learn several important and indisputable facts about Earth’s history that are essential to life today. The majority of readers will know about the “habitable zone” of the solar system, but may not be aware of the requirements of other types of stars, types of galaxies, and favorable regions inside of galaxies. The various ups and downs of the evolutionary pathway were also fascinating to read about, as life on Earth evolved little for billions of years and then rapidly diversified in the Cambrian explosion around 500-600 million years ago. The (controversial) reasons behind this explosion of life are essential for understanding how humans evolved and for assessing the timing of evolution on other hypothetical Earth-like planets. Unequivocally, it is relatively easy to create prokaryotes, even in extreme conditions, while evolving multicellular eukaryotes is much more difficult and requires several intermediary steps.
I found the section on building a habitable earth to be especially thought provoking. The habitable zones in the universe are quite small due to a shortage of heavy metals near the edge and a close proximity of bodies that cause gravity perturbations or eject high-energy particles near the center. But since the Universe is expanding and heavy metals are becoming more common, perhaps solar systems like ours are rare now, but will become more common several billion years from now? Will the exploded remains of today’s stars form into more favorable planetary systems in the distant future? Or, as the authors suggest, will radioactive elements have decayed too much to prevent plate tectonics on newly-developed planets? As with many other topics, there is no definitive answer and the reader is left to form his/her own opinions or conduct further research.
The most difficult challenge facing Ward and Brownlee is testing the Rare Earth hypothesis. By their own admission, there simply is not enough evidence to confirm or deny some of the crucial aspects of their arguments. Not surprisingly, this is the greatest shortcoming of the book and the biggest reason why they are not completely persuasive. But as the authors contend, given the current available evidence, Earth may be the only planet with animal life in this portion of the galaxy, and even possibly the entire galaxy. When considering that the “Drake equation” predictions of a million or more intelligent civilizations, the contention for a far rarer Earth is quite reasonable, even without conclusive evidence for many of the authors’ claims. The book is perhaps best characterized as the pessimistic answer to the overly-optimistic projections for life generated by the discovery of exoplanets in the 1990s.
Still, the mathematical merit must be given adequate consideration. The “sample size” for testing various elements of the hypothesis is quite variable. We have good estimates for the total number of stars in the galaxy and the percentage of which are similar to the sun and with an acceptable amount of heavy metals (small quibble: the authors incorrectly cite the number of stars in the Milky Way as 200-300 million, it actually is 200-300 billion). The population of other life-inhibiting dangers such as quasars and magnetars can be reasonably estimated. But the extremely important presence of a Jupiter-like planet to fend off comets is mostly unknown, as it is only possible to measure “Hot Jupiters” and Jupiter exoplanets with highly elliptical orbits. The only complete sample of a solar system is our own. Earth is the only known planet with a large moon and plate tectonics, with the only other candidates for comparison being Venus and Mars. Models can estimate the probability of some of these factors, but the initial conditions are inherently biased without more complete data from other stars.
Earth is the one and only example of life itself. From our perspective it may appear that animal life here emerged by pure chance. But we do not know the true odds of this chance. Is our evolutionary path the only one, with the other possibilities resulting in life remaining primitive or going extinct? Or is our planet just one possible path of many? The authors do present the possibility that plate tectonics may have actually inhibited life early in the Earth’s history by slowing the oxygenation of the atmosphere. However, the details of the fossil record are so sparse that it is hard to know what actually existed, much less what could have existed in an alternate evolutionary paradigm. It seems naïve to think that Earth’s way is the only way—but it certainly could be.
The opportunity for debate is actually a big part of the appeal of Rare Earth. The question, “Are we alone?” pervades popular culture and makes for great discussion. As mentioned in the preface, Rare Earth emerged from lunchroom conversations. The concluding chapter actually weakens the thesis by laying out alternate explanations to the Rare Earth hypothesis while offering nothing new to counter except references to the previous chapters. I think this is intentional—an attempt to provoke conversation—but perhaps the authors simply lack evidence or do not want to be redundant. Ultimately, there is no way to confirm or deny the Rare Earth hypothesis, so it may be many generations before this book’s legitimacy is decided: either forgotten as an anathema to widespread discovery of other earths, or a groundbreaking beginning to our society’s role as protectors of a very rare and special ecosystem.
See this review and others on my website: www.wxnotes.com
I am nowhere near an expert on this topic, but as a scientist I found this book worthy of a review. I highly recommend it for its clear qualitative explanations of complicated scientific topics and its relatively neutral presentation of both sides of the more controversial topics. While readers may have qualms with at least some portion of the Rare Earth hypothesis, most will learn several important and indisputable facts about Earth’s history that are essential to life today. The majority of readers will know about the “habitable zone” of the solar system, but may not be aware of the requirements of other types of stars, types of galaxies, and favorable regions inside of galaxies. The various ups and downs of the evolutionary pathway were also fascinating to read about, as life on Earth evolved little for billions of years and then rapidly diversified in the Cambrian explosion around 500-600 million years ago. The (controversial) reasons behind this explosion of life are essential for understanding how humans evolved and for assessing the timing of evolution on other hypothetical Earth-like planets. Unequivocally, it is relatively easy to create prokaryotes, even in extreme conditions, while evolving multicellular eukaryotes is much more difficult and requires several intermediary steps.
I found the section on building a habitable earth to be especially thought provoking. The habitable zones in the universe are quite small due to a shortage of heavy metals near the edge and a close proximity of bodies that cause gravity perturbations or eject high-energy particles near the center. But since the Universe is expanding and heavy metals are becoming more common, perhaps solar systems like ours are rare now, but will become more common several billion years from now? Will the exploded remains of today’s stars form into more favorable planetary systems in the distant future? Or, as the authors suggest, will radioactive elements have decayed too much to prevent plate tectonics on newly-developed planets? As with many other topics, there is no definitive answer and the reader is left to form his/her own opinions or conduct further research.
The most difficult challenge facing Ward and Brownlee is testing the Rare Earth hypothesis. By their own admission, there simply is not enough evidence to confirm or deny some of the crucial aspects of their arguments. Not surprisingly, this is the greatest shortcoming of the book and the biggest reason why they are not completely persuasive. But as the authors contend, given the current available evidence, Earth may be the only planet with animal life in this portion of the galaxy, and even possibly the entire galaxy. When considering that the “Drake equation” predictions of a million or more intelligent civilizations, the contention for a far rarer Earth is quite reasonable, even without conclusive evidence for many of the authors’ claims. The book is perhaps best characterized as the pessimistic answer to the overly-optimistic projections for life generated by the discovery of exoplanets in the 1990s.
Still, the mathematical merit must be given adequate consideration. The “sample size” for testing various elements of the hypothesis is quite variable. We have good estimates for the total number of stars in the galaxy and the percentage of which are similar to the sun and with an acceptable amount of heavy metals (small quibble: the authors incorrectly cite the number of stars in the Milky Way as 200-300 million, it actually is 200-300 billion). The population of other life-inhibiting dangers such as quasars and magnetars can be reasonably estimated. But the extremely important presence of a Jupiter-like planet to fend off comets is mostly unknown, as it is only possible to measure “Hot Jupiters” and Jupiter exoplanets with highly elliptical orbits. The only complete sample of a solar system is our own. Earth is the only known planet with a large moon and plate tectonics, with the only other candidates for comparison being Venus and Mars. Models can estimate the probability of some of these factors, but the initial conditions are inherently biased without more complete data from other stars.
Earth is the one and only example of life itself. From our perspective it may appear that animal life here emerged by pure chance. But we do not know the true odds of this chance. Is our evolutionary path the only one, with the other possibilities resulting in life remaining primitive or going extinct? Or is our planet just one possible path of many? The authors do present the possibility that plate tectonics may have actually inhibited life early in the Earth’s history by slowing the oxygenation of the atmosphere. However, the details of the fossil record are so sparse that it is hard to know what actually existed, much less what could have existed in an alternate evolutionary paradigm. It seems naïve to think that Earth’s way is the only way—but it certainly could be.
The opportunity for debate is actually a big part of the appeal of Rare Earth. The question, “Are we alone?” pervades popular culture and makes for great discussion. As mentioned in the preface, Rare Earth emerged from lunchroom conversations. The concluding chapter actually weakens the thesis by laying out alternate explanations to the Rare Earth hypothesis while offering nothing new to counter except references to the previous chapters. I think this is intentional—an attempt to provoke conversation—but perhaps the authors simply lack evidence or do not want to be redundant. Ultimately, there is no way to confirm or deny the Rare Earth hypothesis, so it may be many generations before this book’s legitimacy is decided: either forgotten as an anathema to widespread discovery of other earths, or a groundbreaking beginning to our society’s role as protectors of a very rare and special ecosystem.
See this review and others on my website: www.wxnotes.com
September 2, 2019
I think they're right, but I wouldn't bet the farm on it
Astrobiology, the subject of this excellent book, is a science still in eager anticipation of its first object of contemplation. Professors Ward and Brownlee from the University of Washington, the former a geologist, the latter an astronomer, argue very strongly that such an object will not be what we would call an animal or a metazoan. Certainly the word "intelligent"will not apply to the first extraterrestrial. Their thesis is that our earth is indeed rare, the product of innumerable rare events and unusual conditions, so much so that we should expect to find similar circumstances elsewhere only very rarely. Acknowledging the recent discoveries of extremophiles, single-celled organisms that can live in very harsh environments, the authors aver that microbial life, on the other hand, should be plentiful. They believe, nonetheless, that the leap from microbes to complex life forms is a very rare event indeed.
Their argument is based on all the things that can go wrong. They cite a formidable litany of hindrances including the need for a planet to be the right size at the right distance from a star of the right size and composition, to the need for plate tectonics (for biotic diversity and the recycling of materials) and a large moon (to stabilize the planet's tilt and temperature), to a Jupiter to sweep the system relatively free of deadly planet-crossing bodies, and especially to a very long time period in which to evolve, etc.
Their argument is tantalizing and difficult to fault. We have only one example of the rise of complex life, and it seems reasonable to conclude that the factors that allowed this life to evolve are necessary. But I am troubled. If I look at the factors that led to my birth, my birth as exactly me, the whole process seems rather miraculous. If my parents had never met, if my mother had had a headache that night, if, in fact, she or my father had behaved in any way differently from exactly how they did behave during the time up and including my conception, another little sperm might have fertilized the egg and I would not exist. Or, take a hand at bridge. If you are dealt 13 spades, you can be pretty sure that something fishy is going on since the odds against getting exactly 13 spades are astronomical. However, the odds against being dealt any other exact hand at bridge are also astronomical, in fact the odds are identical. But some combination of cards must be dealt! So the fact that the development of complex life on this planet seems miraculous in the sense that everything had to be just right for it to develop may be a misconception. I think it's akin to the anthropic principle. If our solar system were different perhaps some other creatures would be here rhapsodizing over just how miraculous all the coincidences were that produced them!
The authors, of course, are talking about carbon-based "life as we know it." Since it is massively difficult to speculate on life as we don't know it, especially when considering that 90% of the universe, the so-called mysterious dark matter, is still totally beyond our ken, they are wise to qualify the argument. I would add that life may take on forms and modes that we wouldn't recognize as being "alive." It may be, for example, that the stars are "alive." We know that they are born, they grow, reproduce and die. They spew their seeds, the heavy elements out into space where they attract other elements and form new stars. Such life would be "life as we wouldn't recognize it." There is also the possibility that life may take on forms and modes totally beyond our comprehension, giving us "life as we can't possibly know it." An example would be my friends "the energy beings" who live, reproduce and disappear in a small fraction of a nanosecond, too quick for us ever to be aware of them.
Yes, one may, I hope, speculate. Certainly that is what the authors are doing here. Regardless of how carefully they conform to what is currently known in a scientific sense, and regardless of how carefully those speculations are expressed, they are postulating from a sampling of one. But the authors know this. On page 282 they write, "The great danger to our thesis...is that it is a product of our lack of imagination. We assume in this book that animal life will be somehow Earth-like. We take perhaps the jingoistic stance that...lessons from Earth are not only guides but also rules." Nonetheless they say that "evidence and inference" lead them to believe that the earth is very rare indeed.
There is some redundant repetition from chapter to chapter, which can happen with two authors, and there are the usual "spell-checker" typos, i.e., "out" for "our," etc., that occasionally mar the text, but no more than usual. On page 267, however, they estimate that there are between 200 and 300 million stars in our galaxy. Of course the number is more like 100 billion. They probably meant that there are 200 to 300 million "sun-like" stars in our galaxy. These quibbles aside, I think that the significant value of this book is that, in the process of arguing for their rare earth, Ward and Brownlee are able to share with us their formidable understanding of the latest findings in a number of sciences, especially geology, biology and astronomy, and apply that knowledge to astrobiology. The material on tectonics and mass extinctions is especially interesting. Their recreation of the impact and aftermath of the object that hit the earth at the end of the Cretaceous is strikingly vivid. More than this, it is their enthusiasm in presenting the material that makes this excellent book so very interesting and readable.
--Dennis Littrell, author of “The World Is Not as We Think It Is”
Astrobiology, the subject of this excellent book, is a science still in eager anticipation of its first object of contemplation. Professors Ward and Brownlee from the University of Washington, the former a geologist, the latter an astronomer, argue very strongly that such an object will not be what we would call an animal or a metazoan. Certainly the word "intelligent"will not apply to the first extraterrestrial. Their thesis is that our earth is indeed rare, the product of innumerable rare events and unusual conditions, so much so that we should expect to find similar circumstances elsewhere only very rarely. Acknowledging the recent discoveries of extremophiles, single-celled organisms that can live in very harsh environments, the authors aver that microbial life, on the other hand, should be plentiful. They believe, nonetheless, that the leap from microbes to complex life forms is a very rare event indeed.
Their argument is based on all the things that can go wrong. They cite a formidable litany of hindrances including the need for a planet to be the right size at the right distance from a star of the right size and composition, to the need for plate tectonics (for biotic diversity and the recycling of materials) and a large moon (to stabilize the planet's tilt and temperature), to a Jupiter to sweep the system relatively free of deadly planet-crossing bodies, and especially to a very long time period in which to evolve, etc.
Their argument is tantalizing and difficult to fault. We have only one example of the rise of complex life, and it seems reasonable to conclude that the factors that allowed this life to evolve are necessary. But I am troubled. If I look at the factors that led to my birth, my birth as exactly me, the whole process seems rather miraculous. If my parents had never met, if my mother had had a headache that night, if, in fact, she or my father had behaved in any way differently from exactly how they did behave during the time up and including my conception, another little sperm might have fertilized the egg and I would not exist. Or, take a hand at bridge. If you are dealt 13 spades, you can be pretty sure that something fishy is going on since the odds against getting exactly 13 spades are astronomical. However, the odds against being dealt any other exact hand at bridge are also astronomical, in fact the odds are identical. But some combination of cards must be dealt! So the fact that the development of complex life on this planet seems miraculous in the sense that everything had to be just right for it to develop may be a misconception. I think it's akin to the anthropic principle. If our solar system were different perhaps some other creatures would be here rhapsodizing over just how miraculous all the coincidences were that produced them!
The authors, of course, are talking about carbon-based "life as we know it." Since it is massively difficult to speculate on life as we don't know it, especially when considering that 90% of the universe, the so-called mysterious dark matter, is still totally beyond our ken, they are wise to qualify the argument. I would add that life may take on forms and modes that we wouldn't recognize as being "alive." It may be, for example, that the stars are "alive." We know that they are born, they grow, reproduce and die. They spew their seeds, the heavy elements out into space where they attract other elements and form new stars. Such life would be "life as we wouldn't recognize it." There is also the possibility that life may take on forms and modes totally beyond our comprehension, giving us "life as we can't possibly know it." An example would be my friends "the energy beings" who live, reproduce and disappear in a small fraction of a nanosecond, too quick for us ever to be aware of them.
Yes, one may, I hope, speculate. Certainly that is what the authors are doing here. Regardless of how carefully they conform to what is currently known in a scientific sense, and regardless of how carefully those speculations are expressed, they are postulating from a sampling of one. But the authors know this. On page 282 they write, "The great danger to our thesis...is that it is a product of our lack of imagination. We assume in this book that animal life will be somehow Earth-like. We take perhaps the jingoistic stance that...lessons from Earth are not only guides but also rules." Nonetheless they say that "evidence and inference" lead them to believe that the earth is very rare indeed.
There is some redundant repetition from chapter to chapter, which can happen with two authors, and there are the usual "spell-checker" typos, i.e., "out" for "our," etc., that occasionally mar the text, but no more than usual. On page 267, however, they estimate that there are between 200 and 300 million stars in our galaxy. Of course the number is more like 100 billion. They probably meant that there are 200 to 300 million "sun-like" stars in our galaxy. These quibbles aside, I think that the significant value of this book is that, in the process of arguing for their rare earth, Ward and Brownlee are able to share with us their formidable understanding of the latest findings in a number of sciences, especially geology, biology and astronomy, and apply that knowledge to astrobiology. The material on tectonics and mass extinctions is especially interesting. Their recreation of the impact and aftermath of the object that hit the earth at the end of the Cretaceous is strikingly vivid. More than this, it is their enthusiasm in presenting the material that makes this excellent book so very interesting and readable.
--Dennis Littrell, author of “The World Is Not as We Think It Is”
September 7, 2021
Un ejercicio hermoso de admiración a nuestro planeta
June 17, 2017
Ward and Brownlee's book Rare Earth presents a nice overview of life on Earth and the conditions that influenced its development. They put forward the idea that elsewhere in the universe microbial life might very well be common, but animal life is exceedingly rare.
I think that they take a very restrictive view by laying out all of the specific conditions that occurred for Earth and then suggesting that these are likely absolutely necessary for animal life to arise elsewhere.
The book, published in 2000, is very dated now specifically in our knowledge of exoplanets. The authors suggest that earth-like (in terms of mass & distance from their star) planets might be very rare and we now know that not to be the case.
There are also a few mostly minor errors in the book (they called Pierre-Simon Laplasse as de Liplike and put the discover on Jupiter's big moons in 1612 instead of 1610), but these make me wonder what else they got wrong in the areas I don't know as well.
Seeing as we don't know anything yet about the actual presence or absence of life out the universe, this book adds to the speculation about what we may one day know.
I think that they take a very restrictive view by laying out all of the specific conditions that occurred for Earth and then suggesting that these are likely absolutely necessary for animal life to arise elsewhere.
The book, published in 2000, is very dated now specifically in our knowledge of exoplanets. The authors suggest that earth-like (in terms of mass & distance from their star) planets might be very rare and we now know that not to be the case.
There are also a few mostly minor errors in the book (they called Pierre-Simon Laplasse as de Liplike and put the discover on Jupiter's big moons in 1612 instead of 1610), but these make me wonder what else they got wrong in the areas I don't know as well.
Seeing as we don't know anything yet about the actual presence or absence of life out the universe, this book adds to the speculation about what we may one day know.
February 4, 2018
Is there life in the Universe beyond Earth?
The authors contend that the Universe is probably teeming with microbial life. Even on Earth one can find microbes living under most extreme conditions such as several thousand meters deep in the planet's crust or in the vicinity of deep sea hydrothermal ridges in complete darkness. These earthly conditions are not better than the habitats a microbe can found, for instance, on Mars or Europa, a moon of Jupiter. Enter the microbes' penchant for regularly traveling on rocks between planets and it seems plausible that we do not have to leave behind even our own solar system to find microbial life in several places. Therefore, a more interesting question is whether we could meet E.T., Chewbacca or any other form of multi-cellular, animal, perhaps intelligent, life out there.
Astronomers estimate the number of stars in our galaxy, the Milky Way, to be over 300 billion. If we factor in that our galaxy is but one of hundreds of billions of galaxies, each galaxy with the huge number of its own stars and planets, then the number of possible planets seems gigantic beyond comprehension. Yet, the authors argue in their Rare Earth Hypothesis that sheer numbers are not everything.
There are several criteria which a planet / its star / its galaxy must meet so that a planet may be conducive to complex life. We should exclude stars which are too big, too small, too short-lived to be able to provide planets with a steady flow of energy over an extended period of time. This single restriction disqualifies around 95% of stars. We can neglect whole galaxies which are too young to contain enough metals for formation of Earth-size planets. Planets which cannot steadily stay in the habitable zone either overheat or freeze over, they are lost cases.
Let’s drop in a few more requirements. The ideal planet must have a magnetic field and plate tectonics to be able to maintain stable temperature. The planet must possess a right-sized moon, that’s a rare coincidence, which can stabilize the tilt of the planet's axis. There must be right quantity of water (not too much, not too little) and there must be a Jupiter-like protector to insulate the terrestrial planet from devastating impacts of inbound asteroids. Finally, it requires a great deal of luck to avoid X-ray and gamma ray outbursts of exploding / colliding neutron stars / supernova, which could completely sterilize the planet. As we go through this mental exercise, we do realize that there is a continuously shrinking group of planet candidates which could emerge as habitats for complex life in the Universe. In conclusion, the authors argue that complex life can be extremely rare, significantly rarer than Carl Sagan and other prominent astronomers presumed formerly.
This is a valuable book but it was not my cup of tea. Though I greatly enjoyed its cosmological and geological explanations, the chapters on astrobiology and evolutionary biology seemed too detailed and a bit tedious. Like I said, not my cup of tea, though that's rather my fault, not the book's.
The authors contend that the Universe is probably teeming with microbial life. Even on Earth one can find microbes living under most extreme conditions such as several thousand meters deep in the planet's crust or in the vicinity of deep sea hydrothermal ridges in complete darkness. These earthly conditions are not better than the habitats a microbe can found, for instance, on Mars or Europa, a moon of Jupiter. Enter the microbes' penchant for regularly traveling on rocks between planets and it seems plausible that we do not have to leave behind even our own solar system to find microbial life in several places. Therefore, a more interesting question is whether we could meet E.T., Chewbacca or any other form of multi-cellular, animal, perhaps intelligent, life out there.
Astronomers estimate the number of stars in our galaxy, the Milky Way, to be over 300 billion. If we factor in that our galaxy is but one of hundreds of billions of galaxies, each galaxy with the huge number of its own stars and planets, then the number of possible planets seems gigantic beyond comprehension. Yet, the authors argue in their Rare Earth Hypothesis that sheer numbers are not everything.
There are several criteria which a planet / its star / its galaxy must meet so that a planet may be conducive to complex life. We should exclude stars which are too big, too small, too short-lived to be able to provide planets with a steady flow of energy over an extended period of time. This single restriction disqualifies around 95% of stars. We can neglect whole galaxies which are too young to contain enough metals for formation of Earth-size planets. Planets which cannot steadily stay in the habitable zone either overheat or freeze over, they are lost cases.
Let’s drop in a few more requirements. The ideal planet must have a magnetic field and plate tectonics to be able to maintain stable temperature. The planet must possess a right-sized moon, that’s a rare coincidence, which can stabilize the tilt of the planet's axis. There must be right quantity of water (not too much, not too little) and there must be a Jupiter-like protector to insulate the terrestrial planet from devastating impacts of inbound asteroids. Finally, it requires a great deal of luck to avoid X-ray and gamma ray outbursts of exploding / colliding neutron stars / supernova, which could completely sterilize the planet. As we go through this mental exercise, we do realize that there is a continuously shrinking group of planet candidates which could emerge as habitats for complex life in the Universe. In conclusion, the authors argue that complex life can be extremely rare, significantly rarer than Carl Sagan and other prominent astronomers presumed formerly.
This is a valuable book but it was not my cup of tea. Though I greatly enjoyed its cosmological and geological explanations, the chapters on astrobiology and evolutionary biology seemed too detailed and a bit tedious. Like I said, not my cup of tea, though that's rather my fault, not the book's.
January 29, 2017
Quite a lot wrong with this book and its "theory". Because the authors sets out from the start to poo poo the idea of intelligent life in the universe, they shot themselves in the foot by a) "proving" that it requires a planet exactly like Earth b) intelligent life must evolve exactly as we did and c) making a plethora of speculations in an attempt to prove their case. These have very little basis in science, let alone science fiction! My pet hate is the authors treatment of Pluto. Before any probe even had the chance to visit the demoted planet, Ward set out to systematically pan it is as just another dull rock, describing its topography in great detail, all when it was but a twinkle in the most powerful telescope!
Likewise, the book's "follow the oxygen" paradigm may prove to be equally shortsighted based on ongoing discoveries, animal life is continually being discovered that directly defies the claims of this book. Life on Earth is so full of surprises, that it is completely naive to assume that alien life won't be. Of course, like many of the "facts" the authors put forward, these type of furphies have since proven to be a very wrong assumptions indeed.
The nature of science is that surprising discoveries will be made. But the authors just don't seem to get that! This is a book worth revisiting, because it is basically astrobiology in the dark ages, so many things have already rendered its concept dated.
Likewise, the book's "follow the oxygen" paradigm may prove to be equally shortsighted based on ongoing discoveries, animal life is continually being discovered that directly defies the claims of this book. Life on Earth is so full of surprises, that it is completely naive to assume that alien life won't be. Of course, like many of the "facts" the authors put forward, these type of furphies have since proven to be a very wrong assumptions indeed.
The nature of science is that surprising discoveries will be made. But the authors just don't seem to get that! This is a book worth revisiting, because it is basically astrobiology in the dark ages, so many things have already rendered its concept dated.
September 8, 2021
I really think Earth-like planets and life as we know it is a fluke in a very hostile universe. Honestly, I think our improbability points to an infinite universe or multiverse where wildly long odd bets pay off somewhere in the expanse. I think though that it is very likely that we are alone in our Hubble Bubble and not likely to ever contact other life out there. This book lists many of the factors that make for our rarity. Stable solar systems, stable climates by a huge moon orbiting our planet. The right mix of elements rather sheltered from bombardment. Not hit by AGN or Gamma-ray burst too much. Long odds but in infinity anything is possible. I will drop this story to meditate upon.
update 9/8/2021 First book I came across on the rare earth solution to the Fermi paradox. The great filter for life is behind us and hopefully not in our future. I dunno. I like to think that once a civilization makes it to our level as hard as it is to reach that it has a future. Again I dunno.
https://soundcloud.com/user-154380542...
https://www.theatlantic.com/science/a...
update 9/8/2021 First book I came across on the rare earth solution to the Fermi paradox. The great filter for life is behind us and hopefully not in our future. I dunno. I like to think that once a civilization makes it to our level as hard as it is to reach that it has a future. Again I dunno.
https://soundcloud.com/user-154380542...
https://www.theatlantic.com/science/a...
October 23, 2024
IS COMPLEX LIFE (SUCH AS ANIMALS) "VERY RARE" IN THE UNIVERSE?
Peter Douglas Ward (born 1949) is an American paleontologist and professor at the University of Adelaide. Donald Eugene Brownlee (born 1943) is a professor of astronomy at the University of Washington (Seattle) and the principal investigator for NASA's Stardust mission.
They wrote in the Preface to this 2000 book, "This book ... was stimulated by a host of discoveries suggesting to us that complex life is less pervasive in the Universe than is now commonly assumed. In our discussions, it became clear that both of us believed such life is not widespread, and we decided to write a book explaining why... we have staked out a position rarely articulated by increasingly accepted by many astrobiologists... Perhaps in spite of all the unnumbered stars we are the only animals, or at least we number among a select few. What has been called the 'Principle of Mediocrity'---the idea that the Earth is but one of a myriad of like worlds harboring advanced life---deserves a counterpoint. Hence our book."
In the Introduction, they explain, "In this book we will argue that not only intelligent life, but even the simplest of animal life, is exceedingly rare in our galaxy and in the Universe. We are not saying the LIFE is rare---only that ANIMAL life is. We believe that life in the form of microbes or their equivalents is very common in the universe... However, COMPLEX life---animals and higher plants---is likely to be far more rare than is commonly assumed. We combine these two predictions of the commonness of simple life and the rarity of complex life into what we will call the Rare Earth Hypothesis." (Pg. xiv) Later, they add, "To test the Rare Earth Hypothesis---the paradox that life may be nearly everywhere but complex life almost nowhere---may ultimately require travel to the distant stars." (Pg. xxi)
In the first chapter they observe, "The discovery that life is abundant and diverse in extreme environments is one of the most important of the Astrobiological Revolution. It gives us hope that microbial life may be present and even common elsewhere in the solar system and in our galaxy, for many environments on Earth that are now known to bear extremophile life are duplicated on other planets and moons of the solar system." (Pg. 3-4) Later, they add, "The discovery of extremophilic microbes has radically changed our conception of where life might be able to exist in the Universe... studies are showing that complex life... may have fewer suitable habitats than was previously thought. But just because life COULD exist in a place doesn't mean it is actually there. Life can be widely distributed in the Universe only if it can come into being easily." (Pg. 55-56)
They point out, "Most of the Universe is too cold, too hot, too dense, too vacuous, too dark, too bright, or not composed of the right elements to support life. Only planets and moons with solid surface materials provide plausible oases for life as we know it. And even among planets with surfaces, most are highly undesirable... of all yet KNOWN celestial bodies, earth is unique in both its physical properties and its proven ability to sustain life." (Pg. 35)
They state, "The lesson of Earth's Cambrian Explosion is that two parallel preparatory steps must be taken if complex metazoans¬--animals---are to appear. First, the oxygen atmosphere must be constructed... Second, a very large number of evolutionary adaptations must be concluded to allow the evolution of ... our animals---from the ... bacteria---that began it all. Both of these parallel tracks require time. There do not appear to be any shortcuts. On Earth, one or both required several billion years. And during that time, Earth had to maintain a temperature that allowed the presence of liquid water and avoid what we might call `planetary disasters' of sufficient magnitude to sterilize the evolving foot stocks of animals." (Pg. 156)
They observe, "We can summarize the implications of Earth's history of mass extinctions with regard to the Rare Earth Hypothesis as follows. Mass extinctions probably occurred rarely during the long period in Earth history when life was only of a bacterial grade. With the evolution of more complex creatures, such as eukaryotic cells, however, susceptibility to extinction increased.... As more and more species evolved within the various body plans, susceptibility to extinction decreased again." (Pg. 189)
They suggest, "It may be that plate tectonics is the central requirement for life on a planet and that it is necessary for keeping a world supplied with water. How rare is plate tectonics? We know that of all the planets and moons in our solar system, plate tectonics is found only on Earth. But might it not be even rarer than that? One possibility is that Earth has plate tectonics because of another uncommon attribute of our planet: the presence of a large companion moon..." (Pg. 220) They add, "Without the large moon, Earth would have had a very unstable atmosphere, and it seems most unlikely that life could have progressed as successfully as it has... Unfortunately, there is no evidence on how common large moons are for warm terrestrial planets close to their parent stars. We just don't know, and we probably won't for some time." (Pg. 234)
They summarize, "The Rare Earth Hypothesis is the unproven supposition that although microscopic, sludge-like organisms might be relatively common in planetary systems, the evolution and long-term survival of larger, more complex, and even intelligent organisms are very rare. The observations on which this hypothesis is based are as follows: (1) Microbial life existed as soon as Earth's environment made it possible, and this nearly invincible form of life flourished over most of Earth history... (2) The existence of larger and more complex life occurred only late in Earth history, it occurred only in restricted environments, and the evolution and survival of this more fragile variant of terrestrial life seem to require a highly fortuitous set of circumstances that could not be expected to exist commonly on other planets." (Pg. 243)
They acknowledge, "It is still impossible to observe smaller, rocky planets orbiting other stars. Perhaps such planets... are quite common. But ... We have hypothesized that animal life cannot long exist on a planet unless there is a giant, Jupiter-like planet with the same planetary system---and orbiting outside the rocky planets---to protect against comet impacts... To date, all tend to be in orbital positions that would be lethal, rather than beneficial, to any smaller rocky planets." (Pg. 269)
They also admit, "We assume in this book that animal life will be somehow Earth-like. We take the perhaps jingoistic stance that Earth-life is every-life, that lessons from Earth are not only guides but also RULES. We assume that DNA is the only way, rather than only one way. Perhaps complex life... is as widely distributed as bacterial life and as variable in its makeup. Perhaps Earth is not rare at all but is simply one variant in a nearly infinite assemblage of planets with life. Yet we do not believe this, for these is so much evidence and inference... that such is not the case." (Pg. 282)
This is a provocative, challenging, and intellectually stimulating book, that will be of great interest to anyone seriously studying cosmology, exobiology, life on other planets, and related topics.
Peter Douglas Ward (born 1949) is an American paleontologist and professor at the University of Adelaide. Donald Eugene Brownlee (born 1943) is a professor of astronomy at the University of Washington (Seattle) and the principal investigator for NASA's Stardust mission.
They wrote in the Preface to this 2000 book, "This book ... was stimulated by a host of discoveries suggesting to us that complex life is less pervasive in the Universe than is now commonly assumed. In our discussions, it became clear that both of us believed such life is not widespread, and we decided to write a book explaining why... we have staked out a position rarely articulated by increasingly accepted by many astrobiologists... Perhaps in spite of all the unnumbered stars we are the only animals, or at least we number among a select few. What has been called the 'Principle of Mediocrity'---the idea that the Earth is but one of a myriad of like worlds harboring advanced life---deserves a counterpoint. Hence our book."
In the Introduction, they explain, "In this book we will argue that not only intelligent life, but even the simplest of animal life, is exceedingly rare in our galaxy and in the Universe. We are not saying the LIFE is rare---only that ANIMAL life is. We believe that life in the form of microbes or their equivalents is very common in the universe... However, COMPLEX life---animals and higher plants---is likely to be far more rare than is commonly assumed. We combine these two predictions of the commonness of simple life and the rarity of complex life into what we will call the Rare Earth Hypothesis." (Pg. xiv) Later, they add, "To test the Rare Earth Hypothesis---the paradox that life may be nearly everywhere but complex life almost nowhere---may ultimately require travel to the distant stars." (Pg. xxi)
In the first chapter they observe, "The discovery that life is abundant and diverse in extreme environments is one of the most important of the Astrobiological Revolution. It gives us hope that microbial life may be present and even common elsewhere in the solar system and in our galaxy, for many environments on Earth that are now known to bear extremophile life are duplicated on other planets and moons of the solar system." (Pg. 3-4) Later, they add, "The discovery of extremophilic microbes has radically changed our conception of where life might be able to exist in the Universe... studies are showing that complex life... may have fewer suitable habitats than was previously thought. But just because life COULD exist in a place doesn't mean it is actually there. Life can be widely distributed in the Universe only if it can come into being easily." (Pg. 55-56)
They point out, "Most of the Universe is too cold, too hot, too dense, too vacuous, too dark, too bright, or not composed of the right elements to support life. Only planets and moons with solid surface materials provide plausible oases for life as we know it. And even among planets with surfaces, most are highly undesirable... of all yet KNOWN celestial bodies, earth is unique in both its physical properties and its proven ability to sustain life." (Pg. 35)
They state, "The lesson of Earth's Cambrian Explosion is that two parallel preparatory steps must be taken if complex metazoans¬--animals---are to appear. First, the oxygen atmosphere must be constructed... Second, a very large number of evolutionary adaptations must be concluded to allow the evolution of ... our animals---from the ... bacteria---that began it all. Both of these parallel tracks require time. There do not appear to be any shortcuts. On Earth, one or both required several billion years. And during that time, Earth had to maintain a temperature that allowed the presence of liquid water and avoid what we might call `planetary disasters' of sufficient magnitude to sterilize the evolving foot stocks of animals." (Pg. 156)
They observe, "We can summarize the implications of Earth's history of mass extinctions with regard to the Rare Earth Hypothesis as follows. Mass extinctions probably occurred rarely during the long period in Earth history when life was only of a bacterial grade. With the evolution of more complex creatures, such as eukaryotic cells, however, susceptibility to extinction increased.... As more and more species evolved within the various body plans, susceptibility to extinction decreased again." (Pg. 189)
They suggest, "It may be that plate tectonics is the central requirement for life on a planet and that it is necessary for keeping a world supplied with water. How rare is plate tectonics? We know that of all the planets and moons in our solar system, plate tectonics is found only on Earth. But might it not be even rarer than that? One possibility is that Earth has plate tectonics because of another uncommon attribute of our planet: the presence of a large companion moon..." (Pg. 220) They add, "Without the large moon, Earth would have had a very unstable atmosphere, and it seems most unlikely that life could have progressed as successfully as it has... Unfortunately, there is no evidence on how common large moons are for warm terrestrial planets close to their parent stars. We just don't know, and we probably won't for some time." (Pg. 234)
They summarize, "The Rare Earth Hypothesis is the unproven supposition that although microscopic, sludge-like organisms might be relatively common in planetary systems, the evolution and long-term survival of larger, more complex, and even intelligent organisms are very rare. The observations on which this hypothesis is based are as follows: (1) Microbial life existed as soon as Earth's environment made it possible, and this nearly invincible form of life flourished over most of Earth history... (2) The existence of larger and more complex life occurred only late in Earth history, it occurred only in restricted environments, and the evolution and survival of this more fragile variant of terrestrial life seem to require a highly fortuitous set of circumstances that could not be expected to exist commonly on other planets." (Pg. 243)
They acknowledge, "It is still impossible to observe smaller, rocky planets orbiting other stars. Perhaps such planets... are quite common. But ... We have hypothesized that animal life cannot long exist on a planet unless there is a giant, Jupiter-like planet with the same planetary system---and orbiting outside the rocky planets---to protect against comet impacts... To date, all tend to be in orbital positions that would be lethal, rather than beneficial, to any smaller rocky planets." (Pg. 269)
They also admit, "We assume in this book that animal life will be somehow Earth-like. We take the perhaps jingoistic stance that Earth-life is every-life, that lessons from Earth are not only guides but also RULES. We assume that DNA is the only way, rather than only one way. Perhaps complex life... is as widely distributed as bacterial life and as variable in its makeup. Perhaps Earth is not rare at all but is simply one variant in a nearly infinite assemblage of planets with life. Yet we do not believe this, for these is so much evidence and inference... that such is not the case." (Pg. 282)
This is a provocative, challenging, and intellectually stimulating book, that will be of great interest to anyone seriously studying cosmology, exobiology, life on other planets, and related topics.
August 13, 2021
This is one great book. The authors do an excellent job of explaining complex matters that are intelligible to those of us with less than strong backgrounds in any of the sciences. What they are able to communicate quite effectively is the fragility and improbability of life on earth. This involves numerous factors I never would've considered relevant, never mind critical.
September 17, 2014
Anthropocentric (which never comes from a pretty place) and, in the end, unconvincing. Sure, either position is just a guess, but this is the wrong guess. (See, I can guess too!)
July 20, 2021
Took nearly a year to slow read this. 3.5-4 stars. Good book. a little out of date, but point still stands. The books premise doesn't really need a book to demonstrate, but to the average reader, it all builds to the basic argument the author is building.
October 3, 2009
I consider this one of the best, most though provoking books, I've ever read.
It brings together an eclectic mix of concepts from Astronomy, Geology, Paleontology, Climatology, Genetics, and Evolotionary Biology.
The thesis is simple: That life in the Universe is probably more common that we though 20 years ago, but that intelligent life is probably much more rare than we thought.
He doesn't offer proof, but he presents several independent concepts why the process of evolution created intelligent life needs some "luck".
One case in point. The MOON is important/essential? for the development of intelligence on Earth. The MOON??? Our Moon is an "outrigger" on the rotation of the earth, stabilizing its axis to point more or less in a narrow range of angles with respect to the sun for a couple of billion years. This allows for stability of climate. Without a moon, for some significant portions of Earth's history the axis would be a much higher angles of incidence, causing large portions of the earth to be in daylight or night for months at a time. Having most portions of the earth experiencing cycles of Antartic and Saharan conditions every year would not be conducive to the development of intelligence. Yet the moon, a comparitively large body in relation to the body it orbits, is itself a very unlikely development. We have learned how the moon could have been formed, but it requires collisions of bodies early in the solar system's development of just the right size, at just the right speed and angle of impact, that it would make an odd's maker in Las Vegas blanch.
It brings together an eclectic mix of concepts from Astronomy, Geology, Paleontology, Climatology, Genetics, and Evolotionary Biology.
The thesis is simple: That life in the Universe is probably more common that we though 20 years ago, but that intelligent life is probably much more rare than we thought.
He doesn't offer proof, but he presents several independent concepts why the process of evolution created intelligent life needs some "luck".
One case in point. The MOON is important/essential? for the development of intelligence on Earth. The MOON??? Our Moon is an "outrigger" on the rotation of the earth, stabilizing its axis to point more or less in a narrow range of angles with respect to the sun for a couple of billion years. This allows for stability of climate. Without a moon, for some significant portions of Earth's history the axis would be a much higher angles of incidence, causing large portions of the earth to be in daylight or night for months at a time. Having most portions of the earth experiencing cycles of Antartic and Saharan conditions every year would not be conducive to the development of intelligence. Yet the moon, a comparitively large body in relation to the body it orbits, is itself a very unlikely development. We have learned how the moon could have been formed, but it requires collisions of bodies early in the solar system's development of just the right size, at just the right speed and angle of impact, that it would make an odd's maker in Las Vegas blanch.
This entire review has been hidden because of spoilers.
November 5, 2019
"Perhaps the most likely solution to the Fermi Paradox - "we are alone" - this books raises a lot of excellent points about our extraordinary existence on Planet Earth." - I wrote this a few years ago but recent discoveries have shown that Earth is not rare, that there are planets everywhere. This book like so many science books is completely and utterly wrong - which shows how great science is! Still gets 5 stars for its readability and convincing arguments. But don't go reading this for the "truth". Ward was as wrong as Ptolemy. But Ptolemy was an incredibly smart scientist who had tons of arguments in his favor. So did the "young Earth" theorists and the anti-Darwinists. This is not "bad science". Good science can be "wrong" science. It's important that scientists all understand (and they must) that all of their theories can be wrong. Einstein was wrong on "spooky action at a distance."
January 7, 2013
Complex life is more complex than I thought... After reading this book my thoughts have run the gambit of how big and how alone we really are in this huge and hostile universe. My take from this book is that life, that is human life is very rare indeed. There are too many factors against life as we know it, conditions have to within a very small set of parameters for higher forms to even exist. My thoughts turned to the SETI program and the search for extraterrestrials... Then back to brownlee and ward and if they're correct... The chance of finding anyone like us is slim to none! A great book to read which also drills holes in the Drake equation! We maybe all alone... Which might not be a bad thing after all when you think about it, but the science fiction people will definitely dislike this book.
May 27, 2009
As much as I truly love the optimism of Carl Sagan's billions of billions of civilations in the Universe, and wish it were true ... this book got me questioning for the first time: could be ALONE? Is there no chance of being saved/enslaved in the nick of time by benevolent aliens. Could Earth be as good as it gets? My gut-feel is yes, it's just humans left to fly SpaceShipEarth to her destination and tend to all her creatures great and small. The scientific quest that must be undertaken to discover the truth is physically exploring and analysisng every single star and bit of matter for meta-equavalents of Earth.
February 27, 2011
Very pugnaious, and while the authors throw a lot of science about Earth's position around, they use "might" and "suppose" too often to be completely convincing. I'm admit that there's an optimistic bias to my view of the subject, but I really don't have anymore evidence than they do. That's the problem with the question.
July 19, 2007
two physicists describe earth science and the impact on life as we know it. plate tectonics, co2 levels and the 'habitable zone' are described. ok but not great - too close to fitness of the environment arguments of religious wingnuts.
July 10, 2016
A classic astrobiology read to set the stage for critical thinking necessary to interpret other books on the subject. Although this book is more than a decade old even when I read it a real eye opener. A must read.
December 25, 2015
Very plausible arguments in favour of our lonelines in the observable universe
February 9, 2016
Well written, sound argument. This book fundamentally & irrevocably changed my view on the existence of intelligent life outside our own planet. Now I am a skeptic.
July 10, 2022
Not a science book. It's Christian nonsense. Don't waste your time unless you are already cognitively dissonant.
May 13, 2020
My new favorite book. This should be required reading.
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