Seven Clues to the Origin of Life (Canto) ペーパーバック – 2008/1/12
Kindle 端末は必要ありません。無料 Kindle アプリのいずれかをダウンロードすると、スマートフォン、タブレットPCで Kindle 本をお読みいただけます。
This book addresses the question of how life may have arisen on earth, in the spirit of an intriguing detective story. It relies on the methods of Sherlock Holmes, in particular his principle that one should use the most paradoxical features of a case to crack it. This approach to the essential biological problems is not merely light-hearted, but a fascinating scrutiny of some very fundamental questions. 'I know of no other book that succeeds as well as this one in maintaining the central question in focus throughout. It is a summary of the best evolutionary thinking as applied to the origins of life in which the important issues are addressed pertinently, economically and with a happy recourse to creative analogies.' Nature '… a splendid story - and a much more convincing one than the molecular biologists can offer as an alternative. Cairns-Smith has argued his case before in the technical scientific literature, here he sets it out in a way from which anyone - even those whose chemistry and biology stopped at sixteen - can learn.' New Statesman
'I know of no other book that succeeds as well as this one in maintaining the central question in focus throughout. It is a summary of the best evolutionary thinking as applied to the origins of life in which the important issues are addressed pertinently, economically and with a happy recourse to creative analogies.' Nature
'… a splendid story - and a much more convincing one than the molecular biologists can offer as an alternative. Cairns-Smith has argued his case before in the technical scientific literature, here he sets it out in a way from which anyone - even those whose chemistry and biology stopped at 16 - can learn.' New Statesman
In that discussion someone had remarked (after reading some creationist stuff) that it was just fantastically impossible for the first cell, or even the first nucleotide, to come together more or less by accident. I replied that of course no one serious thinks that the first replicator was a whole cell, or even a modern sort of nucleotide; it was presumably some very low-tech and inefficient thing, just barely able to reproduce itself imperfectly once in a blue moon. After I said that I realized that while it seemed perfectly obvious to me, and that all right-thinking people must agree, I didn't specifically recall any of the right-thinking people in question. So I went and did some research, and (among other things) I found this book.
In "Seven Clues to the Origin of Life", A. G. Cairns-Smith, a molecular biologist and so on at the University of Glasgow, lays out in an amusing and chatty way (including numerous Sherlock Holmes quotations) his argument that yes the first replicator really couldn't have been any of the replicators that we have today, or even anything very much like them. And he presents his own theory as to what they in fact were: inorganic clay crystals of a certain type that seem to have (or seem capable of having) both the requisite ability to do a kind of very low-tech replication, and the potential to have eventually provided the platform on which our current much higher-tech replicators (DNA and all that) got their start.
The writing is extremely clear and readable, aimed at a general non-technical audience, and the book is both fun and short (131 pages including glossary, index, etc). I'm not convinced by his argument that these particular clay crystals were the first replicators, but I'm very convinced that something at least vaguely like them could have been, and that therefore there's no really puzzling problem about how replication got started in the first place. Which is nice, because it's pretty clear that it did. *8)
Highly recommended to one and all. And if you really like the subject, there's apparently a longer and weightier and more technical book, "Genetic Takeover", in which he treats the same subject in more detail (and perhaps without the Sherlock Homes).
It is no shortcoming of this endeavor that a solution is not presented. Cairns-Smith traces the outline of a proposal: 'low-tech', inorganic replicators -- crystal genes in solution -- with the ability to carry information and reproduce, to 'mutate' and evolve, proliferated over long periods of time near the surface of the primordial earth. Clay is identified as a likely source for this crystallization, being stable and ubiquitous in this environment. The regime change from inorganic to organic information carriers arrives in the form of a "genetic takeover", in which organic molecules come to supplant their mineral forefathers. Cairns-Smith describes an intricate dance of the inorganic and organic, as the molecular keys to life -- amino acids and nucleic acids -- were built up amongst the crystalline scaffolding in environments primed for their creation. From here Cairns-Smith speculates on how this major transition to organic information carriers might have completed...
This book is clear, concise, and packed with courageous ideas about a time shrouded in mystery. Although current research favors alternative ideas over Cairns-Smith's crystal genes, aspects of his development remain relevant to today's thinking, and this book is an important and especially accessible early contribution to the understanding of abiogenesis.