River Out Of Eden: A Darwinian View Of Life - S...
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River Out of Eden has five chapters. The first chapter lays down the framework on which the rest of the book is built, that life is like a river of genes flowing through geological time where organisms are mere temporary bodies. The second chapter shows how human ancestry can be traced via many gene pathways to different most recent common ancestors, with special emphasis on the African Eve. The third chapter describes how gradual enhancement via natural selection is the only mechanism which can create the observed complexity of nature. The fourth chapter describes the indifference of genes towards organisms they build and discard, as they maximise their own utility functions. The last chapter summarises milestones during the evolution of life on Earth and speculates on how similar processes may work in alien planetary systems.
This river of DNA originally flowed as one river (one species) which eventually branched into two, three, four, and eventually millions of rivers. Each river is distinct from the others and no longer exchanges water with the others, just as species are isolated reproductively from other species. This metaphor allows Dawkins to explain both the common ancestry of all life, along with the necessity of gradualism in the evolutionary process.
The universe has created an ability to self-replicate using the surrounding materials to make exact copies of itself, including replicas of such minor flaws in copying as may occasionally arise. What follows is what we call life. Never were so many facts explained by so few assumptions. Not only does Darwinian Theory command superabundant power to explain. Its economy in doing so has a sinewy elegance, a poetic beauty that outclasses even the most haunting of the world's origin myths. One of my purposes in writing this book has been to accord due recognition to the inspirational quality of our modern understanding of Darwinian life. There is more poetry in Mitochondrial Eve than in her mythological namesake...Another of my purposes is to convince my readers that \"ways of making a living\" is synonymous with \"ways of passing DNA-coded texts on to the future.\" My \"river\" is a river of DNA, flowing and branching through geological time, and the metaphor of steep banks confining each species' genetic games turns out to be a surprisingly powerful and helpful explanatory device.
The river of Dawkins's title is a river of DNA, flowing through time from the beginning of life on earth to the present - and onwards. Dawkins explains that DNA must be thought of as the most sophisticated information system imaginable: 'Life is just bytes and bytes of information,' he writes. Using this perspective, he describes the mechanisms by which evolution has taken place, gradually but inexorably, over a period of three thousand million years. It is the story of how evolution happens, rather than a narrative of what has actually happened in evolution. He discusses current views on the process of human evolution, including the idea that we all trace back to a comparatively recent African 'Eve', and speculates that the 'information explosion' that was unleashed on Earth when DNA came into being has almost certainly happened in other places in the universe.
Onceevolutionary theory had weakened the case for special providential activity inbiological history, and humans no longer clearly occupied a meaningful place inthe scheme of things, the way was open to question if there was evidence for any divine purpose in the cosmos.According to Paley’s view of the world, God’s concern for the details ofterrestrial life could be made clear by simply opening our eyes to themarvellous designs within nature, but the eyes of evolution look at the samedata and see no concern or purpose whatsoever. Once again, Richard Dawkinsexpresses the situation with characteristic clarity: “The universe we observehas precisely the properties we should expect if there is, at bottom, nodesign, no purpose, no evil and no good, nothing but blind, pitilessindifference.”
Fig. 2: Age-specific rates of death for males and females by 5-year intervals, related to important human life intervals (see bar at top). Drawn using data from Statistics Canada, 1980. Photo: Charles Scriver
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