The Selfish Gene by Richard Dawkins
Ch. 2 - The replicators

If you were ever wondering about the meaning of life, well here it is. We are temporary, disposable survival machines for our genes!

Chapter Two of The Selfish Gene, titled The Replicators, is a fantastic explanation of how the law of evolution is a central principle of natural systems. Dawkins explains how replication can operate within non-living chemical systems, as a precursor for the emergence of life. The general law is ‘the survival of the stable’. This is an extremely elegant theory, showing how natural selection enables simplicity to change into complexity through the grouping of unordered atoms: “Before the coming of life on earth, some rudimentary evolution of molecules could have occurred by ordinary processes of physics and chemistry. There is no need to think of design or purpose or directedness. If a group of atoms in the presence of energy falls into a stable pattern it will tend to stay that way.” (p14)

Emergence of a replicator, a chemical that makes copies of itself, is highly unlikely. However, here Dawkins makes a key point. The early earth had an extremely long time in which such unlikely events could occur. Over the four billion years of life our human timescales are virtually instantaneous. Over the first one hundred million years, a replicator only had to arise once, providing a base from which further complexity including life could evolve.

Genetic copying has three main properties – longevity, fecundity and fidelity. Any replicator which is superior against these properties will tend to expand by natural selection. Dawkins says the early molecules were our founding fathers (p20) and although not conscious or even alive, were in competitive struggle for existence and stability. He speculates that life emerged as these survival machines competed and built protective measures for themselves, evolving into genes.

Here's something I think correlates to this chapter. Some scientists were able to create RNA in a synthesis of early-earth conditions. I remember hearing about this a couple of months ago and if I understand Dawkins correctly this would be one possible form of the first replicator he talks about on pg. 15.

Dawkins: "At some point a particularly remarkable molecule was formed by accident. We will call it the Replicator. It may not necessarily have been the biggest or most complex molecule around, but it had the extraordinary property of being able to copy itself."

from NatureNews . . .

RNA world easier to make

An elegant experiment has quashed a major objection to the theory that life on Earth originated with molecules of RNA.

John Sutherland and his colleagues from the University of Manchester, UK, created a ribonucleotide, a building block of RNA, from simple chemicals under conditions that might have existed on the early Earth.

The feat, never performed before, bolsters the 'RNA world' hypothesis, which suggests that life began when RNA, a polymer related to DNA that can duplicate itself and catalyse reactions, emerged from a prebiotic soup of chemicals.

"This is extremely strong evidence for the RNA world. We don't know if these chemical steps reflect what actually happened, but before this work there were large doubts that it could happen at all," says Donna Blackmond, a chemist at Imperial College London.

Molecular choreography

An RNA polymer is a string of ribonucleotides, each made up of three distinct parts: a ribose sugar, a phosphate group and a base — either cytosine or uracil, known as pyrimidines, or the purines guanine or adenine. Imagining how such a polymer might have formed spontaneously, chemists had thought the subunits would probably assemble themselves first, then join to form a ribonucleotide. But even in the controlled atmosphere of a laboratory, efforts to connect ribose and base together have met with frustrating failure.

The Manchester researchers have now managed to synthesise both pyrimidine ribonucleotides. Their remedy is to avoid producing separate ribose-sugar and base subunits. Instead, Sutherland's team makes a molecule whose scaffolding contains a bond that will turn out to be the key ribose-base connection. Further atoms are then added around this skeleton, which unfurls to create the ribonucleotide.

The final connection is to add a phosphate group. But that phosphate, although only a reactant in the final stages of the sequence, influences the entire synthesis, Sutherland's team showed. By buffering acidity and acting as a catalyst, it guides small organic molecules into making the right connections.

"We had a suspicion there was something good out there, but it took us 12 years to find it," Sutherland says. "What we have ended up with is molecular choreography, where the molecules are unwitting choreographers." Next, he says, he expects to make purine ribonucleotides using a similar approach.

The start of something special?

Although Sutherland has shown that it is possible to build one part of RNA from small molecules, objectors to the RNA-world theory say the RNA molecule as a whole is too complex to be created using early-Earth geochemistry. "The flaw with this kind of research is not in the chemistry. The flaw is in the logic — that this experimental control by researchers in a modern laboratory could have been available on the early Earth," says Robert Shapiro, a chemist at New York University.

Sutherland points out that the sequence of steps he uses is consistent with early-Earth scenarios — those involving methods such as heating molecules in water, evaporating them and irradiating them with ultraviolet light. And breaking RNA's synthesis down into small, laboratory-controlled steps is merely a pragmatic starting point, he says, adding that his team also has results showing that they can string nucleotides together, once they have formed. "My ultimate goal is to get a living system (RNA) emerging from a one-pot experiment. We can pull this off. We just need to know what the constraints on the conditions are first."

Shapiro sides with supporters of another theory of life's origins – that because RNA is too complex to emerge from small molecules, simpler metabolic processes, which eventually catalysed the formation of RNA and DNA, were the first stirrings of life on Earth.

"They're perfectly entitled to disagree with us. But having got experimental results, we are on the high ground," says Sutherland.

"Ultimately, the challenge of prebiotic chemistry is that there is no way of validating historical hypotheses, however convincing an individual experiment," points out Steven Benner, who studies origin-of-life chemistry at the Foundation for Applied Molecular Evolution, a non-profit research centre in Gainesville, Florida.

Sutherland, though, hopes that ingenious organic chemistry might provide an RNA synthesis so convincing that it effectively serves as proof. "We might come up with something so coincidental that one would have to believe it," he says. "That is the goal of my career."




The paper in question is:

Synthesis Of Activated Pyrimidine Ribonucleotides In Prebiotically Plausible Conditions by Matthew M. Powner, Béatrice Gerland and John D. Sutherland, Nature, 459: 239-242 (14th May 2009)

Here's a youtube video related to this RNA experiment . . .

http://www.youtube.com/watch?v=g3idEEz0GEo

You might be tongue-in-cheek here, but I like to keep entirely separate the aspects of meaning and however it happened that we came about. I think there are no implications for the meaning of our lives in the evolutionary process, and I sense that Dawkins thinks that way, too. (Would you agree?) The other reaction I have to Dawkins' summary is that it seems reductive, implying that we are only survival machines for our genes. Some people take offense at this, but actually this is an astounding statement, one fully worthy of the wonder and awe that are said to be an important part of religion.

While I do agree that Dawkins sees meaning and how we came about as seperate, and that the previous poster was speaking somewhat tongue-in-cheek (but I'll let them answer that), I think that Dawkins explains his survival machine theory in such a way that it should not be viewed as reductionist, nor should it offend those that would take exception to his point of view. On more than one occasion Dawkins makes it a point to clarify that he does not mean to imply that we are simply empty vessels at the mercy of our genes, and that our emotions and other mental facilities enable us to make our own choices independent of what may be in the best interest of our genes.

I know I am not doing Dawkins explanation justice, but I think that sometimes it can be easy to confuse when Dawkins is speaking metaphorically with what he truly believes.

Yes. I am being tongue-in-cheek, but isn't it amazing to think about evolution from this perspective—the gene's? Disturbing in a way, but also very compelling to think how we came to be in such a purposeless fashion. Obviously we are not merely survival machines for our genes. We have consciousness and emotions and derive meaning from these things. Love is still profound and meaningful, yet we can also understand it in reductive terms to be a chemical reaction in the brain. Does that diminish it? Not to me it doesn't. And though I can see how some people can get upset from reading The Selfish Gene, I have to agree with Dawkins here . . .

"To accuse science of robbing life of the warmth that makes it worth living is so preposterously mistaken, so diametrically opposed to my own feelings and those of most working scientists , I am almost driven to the despair of which I am wrongly suspected." pg. xiii

If an understanding of evolution causes someone to lose sleep than probably their beliefs were on shaky ground in the first place. Looking at evolution from the perspective of the gene, I think, stretches your mind just a tiny bit, enough to make you say 'wow!'

By the way, I like how Dawkins creates a bit of suspense with that sentence I quoted. It ends Ch. 2 as a sort of cliffhanger. Interesting.

Viewing the gene as the unit of evolution is expansive, not reductionist. A key agenda in The Selfish Gene is to expand people's vision towards an accurate geological perception of time. If we see things that are more permanent and stable as having more reality than things which come and go in a moment, we can start to see what he is getting at. For example the solar system has existed for over four billion years, about 500,000 years for each year of human civilization. Many of our genes have been around for nearly this long too, putting our attempts to reduce reality to the present moment into a big real context. Long after we are dead, our genes could be colonising the stars.

Jean Paul Sartre, in his book Being and Nothingness, founded existentialism on the false theory that only the present moment is real, summarised as 'existence precedes essence'. Dawkins' frame of reference, in an entirely empirical way, shows how the existential attitude is ridiculously arrogant. Dawkins is really opening us to true wonder - as Blake put it

Right, I used the word "reductive" in order to avoid the more negative connotation of "reductionist." As I understand the method of science, it does seek to reduce explanations of phenomena to the most elemental units and is therefore reductive--but this is a strength. The compact summary or theory that results from all the scientific work can then be unpacked to reveal its actual richness of content. This is what Dawkins is doing for us throughout the book.

Stretching your mind is exactly the right metaphor to use. If we can manage to stretch our minds (takes effort and imagination; I haven't achieved it yet), we can then wrap our minds around the concepts Dawkins is teaching. Just like physical stretching, mental stretching can be uncomfortable, as you say, and this is partly why so many people would prefer not to do it.

Robert, the post answering Bryamon above, may explain why I used the word reductive. I'm not sure about your put-down of existentialism, will have to think about it. But your use of the Blake quotation is very apt for what Dawkins is doing.

Bill, I've always regarded the word reductive as a put-down of science by mysticism. You might recall we discussed Unweaving the Rainbow here at Booktalk, in which Dawkins argues that Newton's reduction of light by the prism to its rainbow components is a more expansive way to understand than Newton's critics who said scientific understanding detracts from the mystery of the whole.

I don't agree with your earlier characterisation of Dawkins and de Waal as seeking to shoulder philosophy aside with zoology. It is not about 'reducing' ideas to facts, but rather more a recognition that true ideas are based on facts, so philosophy should be based on zoology. They are providing a foundation for systematic thinking, not asking people not to think. Sartre is a good example of a philosopher who was ignorant of zoology, and who produced an idealist vision which responded to his context but was not well grounded in reality. Zoology provides the 'shoulders of giants' (in Newtons' term) upon which philosophy can be constructed. Who Dawkins is 'shouldering aside' is not the philosophers but the creationists and others who refuse to base their opinions on evidence.

I wasn't around when Unweaving the Rainbow was discussed. I'll put it on my (long) list, though, and I do agree with Dawkins' view. When I said that De Waal and Dawkins wanted to shoulder philosophy aside (as De Waal stated), I was thinking of philosophy as it has existed, not philosophy as it "should" exist, a philosophy grounded in the facts of zoology and other natural science. I'm far from being able to accurately characterize current philosophy, but my impression, for what that is worth, is that philosophy pursues a largely independent agenda. You might be more up to speed on this than I.

People might like to read this review of Unweaving The Rainbow I posted at Booktalk in 2003.