Appearance
Rare Earth: Why Complex Life Is Uncommon in the Universe
Good book. Good recap of history of the planet and of our knowledge of the development of life on it.Nice to read a work in which the pragmatism of the geologist tempers for theory of the astronomer. Good to read that there remain many things the authors don't or cannot know. That's life. Much better, so much better, than reading the nonsense posing as science that astrophysicists churn out when THEY don't know something.From that maelstrom of 200 + IQs we get such nonsense as string theory and the big bang......but I don't recall once reading in this book how everything we observe out billions of light years all started as an infintesimal point .I stopped reading astronomy books twenty years ago when I learned that those more intelligent than I had concluded that galaxies were held in place by strings of matter unimaginably strong etc. None of that bull in this book. Very pragmatic.good show guys. I think we are alone in this little slice of time.
Rare Earth: Why Complex Life Is Uncommon in the Universe
This book is attractively produced and the topics are well organised and well presented. I enjoyed reading it, although I disagree with the authors' premise.The authors' basic thesis is that (1) extraterrestial microbial life is probably common, and (2) extraterrestrial intelligent life is probably rare, if not unique to Earth. Their first conclusion is based largely on the existence of extremophiles, organisms that can survive extremely hostile conditions. Their second conclusion is based on anthropic principle type arguments, many of which have been discussed in earlier works by other authors.Ward & Brownlee are committed to the dogma of naturalism. They admit that "conditions on the early Earth would have been in many ways horrific for natural 'chemistry' experiments involving reactions that now routinely take place in what we humans call 'room temperature'. ... For example, with an oxygen-free atmosphere the amount of ultraviolet radiation reaching Earth's surface would have been far higher than today, making delicate chemical reactions on the planet's surface very difficult." But because "we know that life did arise ... ", they therefore conclude that it must have arisen by naturalistic processes, without any intelligent input.The section on the origin of archaebacteria, and the evolution from prokaryotes to eukaryotes and metazoans are highly speculative. Some difficulties are mentioned and then ignored (as the above). Others are just ignored. For instance, natural selection could not have acted on the simple precursors of prebiotic chemical systems, since they had no survival traits to select until they had reached a minimal level of complexity.Extremophiles also argue against natural selection. Tardigrades are tiny invertebrates that can survive extreme conditions created in laboratories (e.g. extremely high X-ray intensity and hydrostatic pressures, temperatures near to absolute zero, etc.). These conditions far exceed any Earth environment in the history of life, and therefore such hardy traits could not have come about by natural selection.The authors argue for a two-stage development in the evolution of animal life. The second stage is the well-known Cambrian Explosion. This was preceded by an earlier stage involving animals that had differentiated body plans, but were too small to found in the fossil record. This first stage is inferred from the molecular clock. Ward & Brownlee admit that the assumption underlying a molecular clock (that genes mutate at a constant rate) is a matter of "fierce debate", and that "The Wray group's findings were extremely controversial". Nevertheless this is conveniently brushed aside when they conclude that "The Wray work confirms that there were indeed two 'explosion'".The interesting role of plate tectonics in making Earth a suitable environment for life is described at length. The tacit assumption is that conditions that are necessary for life to exist, are also sufficient for life to originate - a giant leap of faith!Stanley Miller's view that "the time necessary to go from soup to bugs may have been far less than 10 million years" is quoted with approval. All this by blind natural mechanisms, when the untiring combined efforts of the world's best minds in biochemistry, sustained over many decades, has come nowhere near to creating the simplest life form from scratch! It seems that when people cease to believe in the Creator, they can believe the most unlikely stories.
Rare Earth: Why Complex Life Is Uncommon in the Universe
The authors theorize that because primitive life apparently (based on scientific evidence) began early in the earth's history that it is likely universal (and may have bounced around from Mars to earth). Once they accept this as a given the rest of the book is about how many factors are uniquely involved to accomodate complex life.This approach glosses over two critical issues.(1) All life on earth is based on the genetic code right down to 'simple' (structurally) viruses (from this point of view it is 'universal'; i.e. all life as we know it). The DNA and RNA processes of the genome are far too complex to arise spontaneously, whether here or from Mars. Modern science suggests that there must be a prebiotic evolution with a DNA precursor. The authors mention a number of theories including the popular "RNA World" theory where the RNA performed all of the necessary functions. However no one has successfully modeled this so it is only a hypothesis bordering on pure speculation. RNA specialist Gerald Joyce has gone so far as to say "The most reasonable assumption is that life did not start with RNA...The transition to an RNA world, like the origins of life in general, is fraught with uncertainty and is plagued by a lack of experimental data." The authors' distinction between 'simple' and 'complex' life from a scientific viewpoint is misguided. The critical first step or 'prebiotic phase' is so far unexplainable and applies to all life. As the authors of a recent unpublished paper (available on the web like many articles) state "The information crisis in prebiotic or chemical evolution stems essentially from two observations: (i) the length of a replicating polymer (i.e. RNA-like template) is limited by the replication accuracy per nucleotide, and (ii) templates that differ significantly from each other cannot coexist in a purely competitive setup. Realistic estimates of the error rate of primitive replication mechanisms predict too scanty information content per template - less than 100 nucleotides - to permit the complete codification of the mechanism in just one template."(2) The earth clearly evolved over time from an original molten mass so one might well expect that as it cooled and water formed that more structurally complex life evolved with it (even if the prebiotic phase is universal). For those interested in the evolution they would be better educated by a book on Evolutionary Dynamics that does not, by a bunch of 'hand waving', spend time speculating about the qualitative effects of the moon on tides and Jupitor on asteroids. There is lots of science on the evolution of complexity and how it can work as opposed to not work. This is not to deny that life in the universe maybe very rare, but this is apparent from our telescopes and the very complexity of the much misunderstood first prebiotic steps. However the inference that these first steps can be taken for granted is not science.
Rare Earth: Why Complex Life Is Uncommon in the Universe
I don't own and I haven't read the book but I agree with the authors that "... while simple, microbial life will be very widespread in the universe, complex animal or plant life will be extremely rare."I would just like to make a simple change in the sentence, adding ",as we know," after the second word "life", so that it would read:"...while simple, microbial life will be very widespread in the universe, complex animal or plant life, as we know, will be extremely rare."Why isn't the History of Science a good lesson to scientists as to the fact that man's perception of reality is in continuous evolution? Why aren't we a little more humble and acknowledge our huge ignorance?
Rare Earth: Why Complex Life Is Uncommon in the Universe
The authors conclude that microbial life is likely abundant in our galaxy and the Universe. Their arguments that this microbial life cannot evolve, are unconvincing. If life can develop, it can evolve. We do not know enough about other stars and their planets to conclude otherwise. Rest easy Science Fiction writers; the book misses its own most significant conclusion.
Rare Earth: Why Complex Life Is Uncommon in the Universe
the illogical Sagan paradigm. Science has been telling us life is rare for decades, finally people are admitting it. Astrophysicist Hugh Ross has documented these things in his book "The Creator and the Cosmos" and "the Genesis Question." Fred Heeren in his book "Show me God" and Michael Denton in "Nature's Destiny."Still this book ignores the question where life came from in the beginning. Some scientists still don't want to address the science of Intelligent Design, but maybe this book will change that.