Maybe we really are alone?
Written: May 15 '04 (Updated May 18 '04)
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Product Rating:
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Pros: Informative and surprisingly lively approach to deep science.
Cons: Entertaining, but falls just short of compelling.
The Bottom Line: Rare Earth is the kind of book that opens your eyes to new areas of science and makes you want to learn some more.
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| trohricht's Full Review: Peter Douglas Ward and Donald Brownlee - Rare Eart... |
Ever been curious about how life evolved on planet Earth? Rare Earth provides a highly accessible window into this topic and many others, and it makes for a fascinating read even if it falls ever-so-slightly short of it's goal: to convince the reader that advanced life is probably unique to Earth.
Writing style and accessibility of info
In assembling this work, authors Ward and Brownlee roam expansively through several areas of science, from astronomy to molecular biology to climatology to planetary mechanics. These are mandatory lessons when discussing the evolution of life, because a lot of factors (from many disparate scientific disciplines) have come into play over the four billion years life has been evolving on this planet. If nothing else, this book will make you seem infinitely smarter at the next dinner party you attend because you'll be able to speak convincingly on the Cambrian Explosion or the atomic composition of stardust.
During the first dozen pages, I was fearful this book would be written at too simple a level. For instance when discussing the temporal aspect of suitability for life in the universe, the authors mention that quasars are "very dangerous objects" with no further explanation. I found this sort of pandering simplicity odd considering one of the authors is an astronomer. But I need not have feared. The authors pick up the level quite nicely, and overall the book was - for me at least - a good balance between ease-of-use and meaningful conveyance of the concepts.
The authors repeat definitions several times throughout the book, rather than assuming you remember every single word from the first time it was mentioned. Even toward the end of the book, rather than using just the word "phyla" they use the phrase "phyla, or basic body plans." Some experts might find this annoying but I found it helpful. It's been a long time since I sat in a biology lecture or dissected a frog.
The basic premise
Life is not rare in the universe. In fact this book suggests that simple life may be nearly ubiquitous - trapped in frozen asteroids or thriving in beds of rock kilometers beneath the surface of various planets or moons. It is possible that amino acids, RNA fragments, or even viable microbes rain down on receptive surfaces across the cosmos. The tricky part, according to the authors, is maintaining stable and conducive conditions long enough for life to take that next step; to evolve from simple bacteria-like organisms to complex metazoans.
Human beings represent the ultimate (from our perspective anyhow) in complex metazoans, and it has taken about 500 million years of steady evolution to arrive here from the first multicellular creatures that made use of specialized cells for specialized tasks. Prior to that, simple life (single-celled creatures or multicellular "communities" without specialized cells) had been thriving on earth for around 3.5 billion years.
Ward and Brownlee contend that the inexorable 4-billion-year progression witnessed here on Earth is anything but the norm. They then provide chapter after chapter of events that they believe are possible evolution killers - events we avoided here on Earth only through happy coincidence. Again, these "proofs" span the worlds of science, giving the reader a little taste of climatology here, a bit of geology there, a pinch of paleontology in the next chapter, etc.
So close, but not quite there
As I already said, Rare Earth is a truly interesting read, but for me it was like a series of proofs that went 80% of the way toward compelling me. Taken in total, they still don't quite add up to one hundred. The book is full of passages that read "researcher X has shown that mechanism Y may be a crucial factor in outcome Z."
But there is always that "may be" or "likely to cause" or "possibility of."
Given the current state of human scientific knowledge, it is impossible to answer many of these questions with any certainty at all. When addressing the topic of life in the universe, we have only one example to use; Earth. We are attempting to do statistics with n=1.
Ward and Brownlee are certainly much more clever than I am, but I will still try to outline some of the nagging doubts that remained for me at the end of this book:
Here on Earth, we complex metazoans have done extremely well as carbon-based life forms utilizing water as a solvent and an oxygen metabolism. But are there other possible metabolic pathways (and indeed evolutionary pathways) available which yield lesser, but still serviceable, amounts of energy?
Here on Earth, plate tectonics and the presence of a large moon appear to have played pivotal roles in regulating climate and maintaining biosphere chemisty, over the time periods necessary for complex life to form. But are there other regulatory mechanisms that might prove effective in maintaining a clement atmosphere on an planet that is the "correct" distance from the parent star?
Here on Earth, intelligent life arose some four billion years after the simplest amino acids managed to bind together. This required a four-billion-year streak of luck to avoid some life-sterilizing calamity. But is it possible for intelligent life to evolve more quickly in planetary terms?
We don't know the answers to these kinds of questions. We are doing statistics with n=1. The book does address all the above points and many more, and the authors acknowledge the tremendous degree of uncertainty surrounding some of the terms in their "equation."
The next half-century of human science will do much to help approximate some of the terms in this equation. Missions to sample the great ocean surmized to exist beneath the frozen surface of Europa will help us understand how (or whether) biology evolves in an extraterrestrial environment. Our ever-improving optical telescopes and telescopic arrays will allow us to peer at the atmospheric chemistry of planets circling distant stars. I have no doubt that if a 2nd edition of Rare Earth were published in 2050 it would be quite a bit thicker and much more compelling.
The Great Unknowns
Strangely, one of the most compelling arguments for me was also one of the most obscure and lacking in hard data - the possibility that galaxies are inherently more hostile places than previously thought. While highly energetic supernovae have the capacity to sterilize life (or at least disrupt the atmosphere) on nearby worlds dozens of lightyears away, there appear to be much more energetic events out there - magnetars - which can sterilize whole sectors to a radius of a thousand lightyears. Unlike that old Hollywood movie favourite the asteroid, which provides many months notice of impending disaster, these phenomena arrive unannounced since their effect travels at the speed of light. We just wake up one morning and the atmosphere is boiling off.
Final words
Ward and Brownlee do make one case quite convincingly; that every single species in existence on planet earth has fought a long hard battle to be here. There is intrinsic beauty to advanced life, and since humans have evolved to the position of caretaker on Earth we have an obligation to consider the possibility that every species we extinct here is a species we extinct from the entire galaxy or even the cosmos.
To use one of the authors' own closing sentences, "We humans are like 2-years-olds, just beginning to comprehend the immensity, wonder, and hazards of the wide world."
Recommended:
Yes
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Epinions.com ID:
trohricht
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Member: Thomas Rohricht
Reviews written: 26
Trusted by: 6 members
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