Rare Earth: Why Complex Life Is Uncommon in the Universe

Their new science

is the field of biology ratcheted up to encompass not just life on Earth but also life beyond Earth. It forces us to reconsider the life of our planet as but a single example of how life might work, rather than as the only example.

The revolution in astrobiology during the 1990s was twofold. First, scientists grew to appreciate how incredibly robust microbial life can be, found in the superheated water of deep-sea vents, pools of acid, or even within the crust of the Earth itself. The chance of finding such simple life on other bodies in our solar system has never seemed more realistic. But second, scientists have begun to appreciate how many unusual factors have cooperated to make Earth a congenial home for animal life: Jupiter's stable orbit, the presence of the Moon, plate tectonics, just the right amount of water, the right position in the right sort of galaxy. Ward and Brownlee make a convincing if depressing case for their hypothesis, undermining the principle of mediocrity (or, "Earth isn't all that special") that has ruled astronomy since Copernicus. --Mary Ellen Curtin

Product Description
The sweeping diversity of complex life on Earth, Ward and Brownlee argue, evolved out of an extraordinary set of physical conditions and chance events that would be extremely hard to duplicate- though not impossible. Many planets throughout the vastness of the Universe may be teeming with microbial life, but advancement beyond this stage is very rare. Everyone with an interest in the possible extent of life in the Universe and the nature of life's evolution on our own planet will be fascinated by RARE EARTH.

"...likely to cause a revolution in thinking..." The New York Times

"...[the book] has hit the world of astrobiologists like a killer asteroid..." Newsday (New York)

"...a sobering and valuable perspective..." Science

"...a startling new hypothesis..." Library Journal

"...Peter Ward and Donald Brownlee offer a powerful argument..." The Economist "...provocative, significant, and sweeping..." Northwest Science & Technology

"...a stellar example of clear writing..." American Scientist

Read this book and see: 1. Why the moon and Jupiter are essential for our existence. 2. Why a system of plate tectonics is vital for the development of life forms. 3. The effects that mass extinctions have had on evolution. 4. Why life may have originated in the deep ocean near hydrothermal vents. 5. Why earth is very lucky to be located on the far edge of our galaxy.

For the scientific oriented layman this book is a true gem.


Absolutely Excellent   March 5, 2000
Paul Castonguay (Wilmington, MA USA)
26 out of 28 found this review helpful

This is the best book that I have seen on the subject of extraterrestrial life and the possibility of its occurrence beyond our solar system in a long time. In order to make the most accurate prediction possible the book makes use of the strongest evidence we have to date, our knowledge of our own solar system. Using very wide breadth, the authors rationalize the following simple theme, "The occurrence of simple microbial life is pervasive in the universe, but the occurrence of more complex, multi-cellular life is not.

From this book I now realize that the number of natural phenomena affecting the possible occurrence and evolution of complex life in one of our neighboring stars is far greater than I ever imagined. I thank the authors for enlightening me on this subject. Perhaps in future I won't be as disappointed as I was during the first Viking landing. I really did think they would find vegetation on Mars, and I'm still upset about it.

The authors of "Rare Earth" present their subject very well, although perhaps not in a style that would excite the average public, as did Carl Sagan and Issac Isamov in their science books. Indeed, I recommend that the authors of this text consider rewriting it in a more popular form, with plenty of illustrations. Hey, people love pictures, myself included.

The controversy between the people at SETI and the authors is unfortunate. I believe both sides have a lot to gain from each other's work. In my opinion it was a mistake for the authors to have included, near the very end of the book, references to SETI. The antagonism created was predictable. I myself am a participant in the seteathome project, having completed 225 work units so far. However, I do not allow my excitement over the possibility of receiving an alien signal stand in the way of my objectivity in the face of the best hard evidence we have to date. Besides, I take it not as fact, but simply as the best prediction I have heard anyone say so far. It is the closest to fact that we can get at this time. Hopefully soon we will get closer.


Rare Earth   March 11, 2002
Pauline J. Pate, Ph.d. (Olivet, Michigan United States)
15 out of 15 found this review helpful

I discovered this title in a review in the Boston Sunday Globe a few years ago and decided to try reading the book. To my great pleasure, I found that the authors had done their job well. Although they are pretty sure, given the present state of our knowledge, that advanced life is almost improbable elsewhere in the universe, they continually provide views apposing theirs....so the book is not merely a vehicle to broadcast their own bias [note especially their summation: pp 282-287] They also assert quite strongly that since these studies are just beginning, future discoveries could completely alter the picture as they see it. In addition, the writing, especially considering the material they are discussing, is surprisingly easy to read and understand and totally lacking the 'jargon' so prevalent in today's academic world. I highly recommend this book to anyone who really wants to consider the implications of their thesis.


The Thesis That Spells Death For Modern Science Fiction   September 5, 2000
Paul Cook (Tempe, Arizona USA)
26 out of 29 found this review helpful

This is one of the most astonishing books I have ever read. Its thesis, that complex life similar to life on the Earth, is probably very rare in the galaxy, if not the universe. The authors meticulously build a case for Earth's special place in the cosmos, showing how bacterial life might be common but that anything bigger than simple organisms might not be able to survive the ravages of time and comets and wandering axial tilt. As other readers have pointed out, this doesn't necessarily mean that silicon-based life or some other kind of life can't exist in the universe, but it does demonstrate that Fermi's Dilemma might in fact be true. As a science fiction writer, I was stunned at how much this book could change the way science fiction is written. No more Star Trek universes with complex life in every system, no more "federations" or "foundations" or "assemblies" of thousands of inhabited worlds. According to the thesis Ward and Brownlee present, habitable worlds might be few and far between. Humans may very well find no other worlds beyond the Earth upon which to live. RARE EARTH will make it difficult to read books or watch movies that envision a galaxy filled with wonderful and curious creatures, where humans spread out across the galaxy as if they were so many islands in Polynesia. And if the Rare Earth hypothesis is true, then we are also obliged to get our act together here and now if we are going to become a space-going species. I think this book puts a lot of science fiction writers out of business. It certainly makes a lot of science fiction, including my own, seem downright silly.


Statistics on a single sample   November 19, 2000
Leonardo Alves (Houghton, Michigan USA)
19 out of 21 found this review helpful

This is certainly a great book. It is bound to age quickly since most of the book is based on really ground-breaking discoveries and propositions that are many times challenged shortly after their publication. The book presents a paradoxical theory that says that life is widespread on the universe but most of the times it doesn't go much beyond the very simple organisms on the first evolutionary steps.

Complex life as we see on earth, the book says, must be extraordinary rare if not unique. The idea is revolutionary and the book is written in a very compelling way.

The idea certainly goes against the mainstream challenging consolidated ideas like the Drake Equation. The Drake Equation, devised by Dr. Frank Drake in 1961 is a famous way to estimate the number of intelligent civilizations able to communicate within our own galaxy. This important estimate is one of the pillars for projects like the SETI (Search for Extra Terrestrial Intelligence).

One of the most interesting ideas presented in the book in my opinion is the possibility of exchange of microorganisms between planets and moons within our solar system. Meteor or comet impacts in planets would eject rocks that could carry live microorganisms to neighbor planets. This would happen more often in smaller planets subject to smaller gravitational force and with thinner atmospheres like Mars. Life as we see it on earth, the book says, might actually have started in Mars. However the book doesn't consider the artificial process of seeding life what is for me the lost factor on Drake's equation, the colonization factor. An advanced civilization, even a unique one, could very well have spread life on the universe bypassing the first evolutionary steps and making complex life feasible even on planets that are for a shorter period of time at the solar system habitable zone. If nobody did it before we, humans, might very well start doing in the near future.

Many are, according to the book, the reasons why earth displays such a lush biodiversity. Things that we many times take for granted like plate tectonics, Earth's magnetic field, the presence of other planets like Jupiter and Mars, the size and stability of our Sun and Earth's basic composition are paramount to our very existence. The odds of reproducing such favorable conditions are, according to the book, slim.

The book covers a wide range of subjects from astronomy to biology passing through geology, paleontology, climatology, and many other ologies. But don't panic, the book is written in a way that you can read it and enjoy it even if you lack the basic knowledge in one or more of the subjects covered. This is done by constantly restating the key points presented in every chapter.

This is a fascinating book on a fascinating topic. The biggest problem is that we try to study or even predict the nature of life in other planets based on our unique sample, Earth. As any statistician would agree it's hard to make good statistics on only one sample.

Leonardo Alves, November 2000