River Out of Eden
River Out of Eden: A Darwinian View of Life is a book by Richard Dawkins detailing elements of evolution. It was written in 1995 and was illustrated by his then wife,
the Second Romana Lalla Ward. It is a fairly quick read, with subtle notes of British humour thrown in to keep the reader up all night.
River makes few new assertions, deferring to evidence from biological studies and experiments to make its points and refute antiquated notions, related through poetic elegance. There is an underlying current of Dawkins' signature atheism, but not overwhelming, and mostly limited to the generally accepted ideas against young earth creationism and Biblical literalism. To Dawkins, evolution is both more amazing and more likely than an intelligent designer, opinions that do come through as the book progresses.
 The Digital River
In the first chapter, Dawkins states a fundamental reality that links all (currently) living beings, from humans to protozoa to trees and fungi: "Not a single one of our ancestors died in infancy." The corollary to this statement is that the world is full of "living beings that have what it takes to become ancestors". From these two realities, Dawkins expands throughout the rest of the book.
Dawkins likens the passage of DNA from parent to offspring over millenia to a digital river. In this case he uses "digital" to mean "that which can be counted", and explains the differences between digital codes, from the binary language of computing to the more complex pulse code modulation of telephone systems, to illustrate DNA as a base-4 language. Unlike analog signals, which depend on energy and can degrade (or lose information) over time, digital signals encoded like words on a book—thus, a DNA signal does not change much over time, though copies can contain errors from the original.
Dawkins also makes notes of the event of speciation, usually occurring due to a separation by geography, as something that would be unnoticed to any observer as it happens very slowly over time (hundreds of thousands of years). When the digital rivers of two different organisms become distinctly different enough that they are unable to procreate—or, at the very least, unable to provide non-sterile offspring—they are said to be two different species: Dawkins illustrates this point with the differences between grey squirrels and red squirrels.
 All Africa and Her Progenies
Dawkins begins the second chapter by refuting a claim that, per cultural relativism, one explanation for a phenomenon, such as the moon hanging in the sky, is equally relevant to any other—that myth is relative to the culture who holds it, and that science is simply the explanation relevant to Western cultures. He calls bollocks on this one—why should an uninformed, unevidenced claim stand on equal ground as a claim that has been proven to be more correct?
The rest of the chapter is devoted to the Out of Africa theory, explaining mitochondrial DNA and Mitochondrial Eve, and in a fairly humanist bent, taunts the reader into recognizing that in any sufficiently large group of people, such as in a football stadium, you are almost certain to run into many cousins (or coancestors) that aren't that far removed from you. He then extrapolates this notion to more distant relatives, such as gibbons, then monkeys, then horses, following the digital river back all the way to the first bacteria from which mitochondria are descended.
 Do Good By Stealth
In the beginning of the third chapter, Dawkins relates a letter he received from an atheist-turned-clergy member who was convinced that there must be a Creator from observing how a certain species of orchid tricks a certain species of wasp into pollenating it by resembling a sexual partner. Not only does this appear to be the only evidence that turned the former atheist, the writer was incredibly certain that there was no other explanation.
Dawkins then proceeds to relate examples of "trickery", both occurring in nature and artificially induced in the laboratory, across many different species. He even includes humans, with the example that many humans become sexually aroused even by crude caricatures of the appropriate gender, let alone an actual human in full monty (or indeed, even if clothed).
To further refute this idea, he argues that if a trait (such as the eye) or a behavior (such as the intricate dances of honey bees) were designed—that is, perfect from the time of creation—then there would be no evidence of adaptation or development between species. How many human inventions, such as the automobile or the airplane or the computer, were perfect on the first try? Such concept of perfection, which he refers to as being "brittle", is astronomically unlikely: a more likely path is that such traits and behaviors, as evident by the information travelling along the digital river, were refined slowly over time. For example, a species of sea life that lives deep in the Mariana Trench at 1000 atm is simply a species that is slightly stronger than one that lives at 999 atm, which is a species that is slightly stronger than one that lives at 998 atm, and so on backwards to one that survives only at sea level. One species isn't better than the other for living at a higher level of pressure; it just makes use of a resource that wasn't being used by the slightly weaker species.
Furthermore, he shows that some traits (especially the eye) are acquired after speciation (in a phenomenon called convergence), and that such emergence of traits does not take long relative to the age of life on the planet as a whole.
 God's Utility Function
In contrast to his clerical friend who found faith through the wasp, Dawkins relates that the wasp was responsible for Charles Darwin's loss of faith. Darwin had a problem with the idea of a deity that would design a species of wasp that would paralyze caterpillars in order to lay eggs and let the larvae feast on the caterpillar's innards while the caterpillar is still alive.
Dawkins then posits, if there is indeed a Creator, then it must be possible to reverse engineer a species in order to determine its purpose—that is, the why behind any living thing. After all, human creations have a purpose—any simple tool would suffice as an example. The cheetah appears to be designed to chase and take down gazelles; gazelles, on the other hand, appear to be designed to outrun the cheetah. If this is the case, then does said Creator have a sick sense of humor or a macabre lust for violence?
After providing many more examples of violence and pain in the animal kingdom, he states the more likely reason is that nature is neither cruel nor benevolent. It simply is. The purpose of the cheetah is not to kill gazelles—the purpose of the cheetah is to survive to procreate more cheetahs, and gazelles are simply a means to an end. Similarly, the purpose of the gazelle is to survive to procreate more gazelles, and the end-all of all species are to continue the species. How a species continues to propogate is evident by the traits and behaviors of the species. Dawkins goes into great detail about gender selection, whether forced (by the fastest spermatazoa) or decided (by heterogenity), as it pertains to propogation.
 The Replication Bomb
This ultimate goal of all species (to continue the species) is observed not only at the macro-level, but also at the level of DNA, a series of molecules clumped to form complex arrays of proteins with the sole purpose of self-replication. Dawkins remarks that self-replication is not unique to DNA—various chemical structures such as tartrate crystals duplicate themselves by attracting similar atoms and forcing them into their unique positions—while acknowledging that chemists still don't have all the answers as to why this occurs.
But growth for the sake of growth appears to be the raison d'être for all species on the planet—no one species makes a universal decision to regress, degenerate or give up altogether—and the world is currently in the midst of an explosion of genetic information that nears exponential growth. The digital river must continue to flow, and while humanity may not know its course, it seems clear that it will continue to work towards continuous replication.
Dawkins ends with a proposed outline for the thresholds any digital river must cross over time, from molecular replication to space travel. He also includes several plugs for earlier works (such as The Selfish Gene) and a bibliography.
 See also
- River Out of Eden by Richard Dawkins