While several books have been written on the topic of evolution, very few have dealt head-on with the issue of the origin of life on our planet, a necessary precursor to natural selection and of evolution itself. As Carl Sagan elegantly summarized in 1961: "It is evident that once a self-replicating, mutating molecular aggregate arose, Darwinian natural selection became possible and the origin of life can be dated from this event. Unfortunately, it is this event about which we know the least."
In this splendid thesis, minerals expert and exobiologist, Robert Hazen, takes on this difficult task. Early in the book, he establishes the notion of "emergence" as a necessary corollary to "entropy". The second law of thermodynamics states that entropy (and consequently, the disorder in the universe) must increase. But how, Hazen asks, does the astonishing level of emergent complexity also arise amidst this constant state of flux?
In addressing this question, Hazen brings to the fore the science of emergence - how do complex systems develop, and how do they display novel collective behaviors based on the interactions of fundamentally dissimilar components? He traces several lines of scientific investigation that attempt to explore how our planet may have progressed from non-life to the first living cell. How did basic chemical elements like hydrogen, carbon, and oxygen ultimately form complicated sugars, proteins, amino acids, and eventually complex nucleotides like RNA and DNA that ultimately established a human footprint in the evolution story? How did lipids and cell membranes form, thus enabling the first structures to regulate drastically different environments inside and outside a cell, thereby helping establish some semblance of order between wildly different acidic and alkaline states that dominated early earth? Did this happen spontaneously or was it dependent on the prebiotic soup of chemical elements that existed billions of years ago before life formed? Did life need the vast oxygen at the surface, or did it originate in the hydrothermal vents deep in the ocean's crust? What came first - genetics or metabolism, did molecules first learn to self-replicate and then generate energy for survival, or the other way around?
This is a marvelous work of science, a dazzling account of a cadre of scientists tackling one of the most profound questions about our existence, and in a manner that is entirely Popperian (i.e. a theory must make testable predictions that might be proved false by empirical tests). Hazen uncovers the world of the primordial, and does it with a verve that almost makes the reader yearn to get into a submersible to go collect prehistoric Archea samples from a deep-ocean volcanic vent for some origin-of-life hypotheis testing of their own.
One comes away wondering whether the simultaneous existence of entropy and emergence on our planet is the reason why so many religions like those of the Book as well as the Eastern faiths like Hinduism represent Godhead as simultaneously a Creator and Destroyer? Go figure, and while pondering, don't miss this wild excursion of 250-odd pages...