Giordano Bruno 2008-04-08
13 of 14 people found the following review helpful:
Most readers, I assume, would declare that Life is Plausible enough, as long as they haven't overspent their Visa cards. Obviously authors Kirschner and Gerhart must mean something else, but their literary gifts are not always equal to their scientific insights. This is difficult matter, made more difficult by somewhat obtuse writing. It took me weeks to read this book and fathom its particular content, and yet I'm giving the book all five stars because of the importance of its insghts.
A more informative title would be "The Plausibility of Evolution as an Explanation of the Diversity of Life." The most inveterate critics of the neo-Darwinian theory of evolution point to the diversity of life forms and the implausibility that such diverse forms, each functionally adapted, could have evolved by random mutation, through minute increments of change, evn in the course of billions of years. Kirschner and Gerhart attempt to answer that objection with a new theory of evolution at the sub-cellular level, which they call "facilitated variation." Honestly, I think they're on to something, though I don't find their new synthesis so very different from the ideas implicit in Sean Carroll's notions of evo-devo -- evolutionary development. Rather than try to express the core ideas of facilitated evolution by myself, I'll give you the authors' own words:
The selection for a small number of conserved core processes versatile enough to be used in many different contextsto support the complexity of large multicellular organisms is a product of selection for physiological adaptability. As a side effect, core processes with high adaptability have a high capacity for weak linkage. Such processes are responsive to genetic changes of regulation. They have been used inmany different combinations at many different times and places in the organism's development and physiology, so that it is likely the processes capable of weak linkage pose little barrier to future use in different combinations, times, places, and amounts...
Much of the skepticism over the years about the capacity of random mutation or genetic reassortment to generate phenotypic change has arisen from the assumption that genetic changes must create very specific, multiple, complex phenotypic changes. Our view is that specificity and complexity are already built into the conserved processes, as is the propensity for regulatory coupling.
Well, there you have it, from roughly the middle of the book. If it makes crystalline sense to you, perhaps you don't need to read further. If it makes no sense at all, perhaps you'd better read something else. If it makes some sort of sense but you want a good deal more evidence and explication, then you might consider taking on the whole book.
The most fundamental idea here is that evolution MUST occur first at the level of molecules. Darwin was looking through the wrong end of the telescope by theorizing evolution of species, though in his time and place no other viewing point was available. Darwin observed evolution of whole organisms as "descent with modification," just as any orchid fancier, guppy breeder, or paleontologist can and must observe it. Then came the geneticists, who salvaged Darwinian evolution from the critics who demanded evidence of a mechanism. But even the mapping of the genome hasn't quelled all objections of implausibility, for reasons that Kirschner and Gerhart restate in their opening chapters. At the cellular component level, however, the mathematically possible mutations are so incredibly numerous that success by random variation, again and again in the course of phenotypic evolution, seems utterly unbelievable. That's where our authors enter the discussion.
Advocates of "Intelligent Design"! If you detect a note of challenge in my erratic summary of The Plausibility of Life, you're on the money. I challenge you to read this book carefully and critically. If you can't make heads or tails of it, you'd better modestly trim your ID sails. If you understand it well enough to venture a refutation, I'll be happy to hear from you.
