Ridley writes that the switches controlling our 30,000 or so genes not only form the structures of our brains but do so in such a way as to cue off the outside environment in a tidy feedback loop of body and behaviour. In fact, it seems clear that we have genetic "thermostats" that are turned up and down by environmental factors. He challenges both scientific and folk concepts, from assumptions of what's malleable in a person to sociobiological theories based solely on the "selfish gene".

Ridley's proof is in the pudding for such touchy subjects as monogamy, aggression, and parenting, which we now understand have some genetic controls. Nevertheless, "the more we understand both our genes and our instincts, the less inevitable they seem". A consummate populariser of science, Ridley once again provides ...
fantastic, 2006-05-02
This book is amazing. A fantastic read about the concept and argument surrounding nature and nurture, genetics vs environment. On a par with his other book.

Dawkins re-initiated the debate over evolution's mechanics with The Selfish Gene. For his lucid explanation of the gene as the foundation for life's workings, he was dubbed The Great Reductionist by those uncomfortable with the concept that genes tend to override the treasured idea of "free will" overriding Nature. With River Out of Eden, Dawkins proves his ability by presenting an even more comprehensible account of how DNA is the foundation for life's mechanics.

He begins with the idea that all life had ancestors - all of which succeeded in producing offspring. Their success at reproducing overshadows the fact that most life forms ultimately went extinct over the vast span of Earth's time. Extinction is due to failure to produce offspring that survived to further reproduce new generations. The reasons for this failure are uncountable and obscure, but the issue remains success or failure. Tracing the ancestral line allows us to envision rivers of life. The rivers aren't composed of water, but of DNA. DNA over time, acts as a "digital river" with sections turning on or off in the process of making proteins. And proteins are the bricks that build organisms and all their parts.

From an almost purely descriptive beginning, Dawkins moves on to demonstrate how many of those "parts" could evolve over the many millennia available to them. Among the favourite organs used to oppose natural selection is "the eye". How could such a complex part of life work half complete? Well, for starters, better than 49% complete. A statement that can be applied to all the body parts in various organisms when viewed over the long stretch of years available to change gradually. Wings, finding mates, locating food sources, all the "complex functions" we see in today's life came from earlier, simpler beginnings. Dawkins' chapter "God's Utility Function" is a must read and understand for anyone wishing to comprehend how many of these features came into existence. They didn't all arrive in a finished state.

Dawkins is adept at illustrating his points. Among his more clever tricks is the portrayal of a sentence reading clearly even with different typefaces for each word. You can still read and understand the meaning. But the appearance differs in each case. He also gives an excellent account of how genes govern energy expenditure for various types of creatures. Each has its own variant, but an "audit" of how the genes benefit from the arrangement reveals why it's a successful strategy.

The key to all these patterns is the idea that somehow, somewhen, a molecule that later became DNA learned to replicate. He posits Graham Cairns Smith's suggestion that DNA, or more likely its precursor, RNA, learned the trick from clay crystals. This remains the most likely explanation for life's origins, but requires the reader to recognize that the replicating molecule preceded any discernible organism. Cairns Smith's concept removes forever the idea that life's driving force occurred by chance. It was a relatively simple chemical and physical process. It may not appear elegant, but the mechanism has the elegance of plausibility.

This whole book carries the argument against "creation by design" into the camp of Darwin's enemies. Dawkins lists the contentions of the "creationists", then adroitly unravels them through pure logic and good science. Those who feel daunted by arcane biological treatises on life need only take up this excellent summation of why Darwin was right. Those who quail at the idea DNA drives our existence can take heart. It's all part of what's required in achieving a better idea of who we are. A major step in that understanding is in this book. [stephen a. haines - Ottawa, Canada\