On Evolution

By Psyche | January 12, 2009

Richard Dawkins’ The Blind Watchmaker, first published in 19861, was written to counter arguments made in favour of creationism by the eighteenth century theology William Paley’s Natural Theology, published in 1902.

Paley is perhaps best remembered today for his watchmaker analogy, intended as an argument in favour of the existence of an intelligent designer, or god. This was first seriously challenged by Charles Darwin’s theory of natural selection (the consequence of, or process by which “favourable” traits become prevalent and “unfavourable” traits become rarer), made well known in his The Origin Of Species first published in 1859. Dawkins further decimates Paley’s theory, arguing instead for a “blind” watchmaker, as highly complex systems can be produced by a series of small, cumulative – yet naturally selected – steps, rather than relying on a supernatural designer.

If you walk up and down a pebbly beach, you will notice that the pebbles are not arranged at random. The smaller pebbles typically tend to be found in segregated zones running along the length of the beach, the larger ones in different zones or stripes. The pebbles have been sorted, arranged, selected. A tribe living near the shore might wonder at this evidence of sorting or arrangement in the world, and might develop a myth to account for it, perhaps attributing it to a Great Spirit in the sky with a tidy mind and a sense of order. We might give a superior smile at such a superstitious notion, and explain that the arranging was really done by the blind forces of physics, in this case the action of the waves. The waves have no purposes and no intentions, no tidy mind, no mind at all. They just energetically throw pebbles around, and big pebbles and small pebbles respond differently to this treatment so they end up at different levels of the beach. A small amount of order has come out of disorder, and no mind planned it.2

Dawkins explains that, of course, “[s]imple sieving, on its own, is obviously nowhere near capable of generating the amount of order in a living being”; however it serves well as an example of non-random selection. He then goes on to make the essential distinction between single-step and cumulative selection, writing that in “single-step selection the entities selected or sorted, pebbles or whatever they are, are sorted once and for all. In cumulative selection, on the other hand, they ‘reproduce’; or in some other way the results of one sieving process are fed into a subsequent sieving, which is fed into…, and so on. The entities are subjected to selection or sorting over many ‘generations’ in succession. The end-product of one generation of selection is the starting point for the next generation of selection, and so on for many generations.”3

Self-replication is defined as the property which is the “basic ingredient of cumulative selection”4, and the mechanistic manner in which this replication manifests is emphasized. Dawkins characterizes the difference between self-replication in living versus non-living organisms as follows:

What is special [about living things] is that these molecules are put together in much more complicated patterns than the molecules of non-living things, and this putting together is done by following programs, sets of instructions for how to develop, which the organisms carry around inside themselves. Maybe they do vibrate and throb and pulsate with ‘irritability’, and glow with ‘living’ warmth, but these properties all emerge incidentally. What lies at the heart of every living thing is not fire, not warm breath, not a ‘spark of life’. It is information, words, instructions. If you want a metaphor, don’t think of fires and sparks and breath. Think, instead, of a billion discrete, digital characters carved in tablets of crystal. If you want to understand life, don’t think about vibrant, throbbing gels and oozes, think about information technology.5

Yet this copying is not “perfect”, he writes: “Evolution occurs because, in successive generations, there are slight differences in embryonic development. These differences come about because of changes (mutations)…in the genes controlling development.”6

A few theories are offered for the ultimate origin of life, the timescales involved are explained in detail, but the basic idea can be summarized as follows:

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After many generations of cumulative selection in a particular place, the local animals and plants become well fitted to the conditions, for instance the weather conditions, in that place. If it is cold the animals come to have thick coats of hair, or feathers. If it is dry they evolve leathery or waxy waterproof skins to conserve what little water there is. The adaptations to local conditions affect every party of the body, its shape, and colour, its internal organs, its behaviour, and the chemistry in its cells.7

The animals which “come to have” these thick coats do so because the ones which first displayed this mutation are naturally better adapted to survive the colder conditions: they are more likely to endure longer than those with thinner coats who die of exposure, thus they breed and pass on the gene “for” thicker coats to their offspring, who in turn keep warmer than those who survived with thinner coats, and so on. He stresses that the “timescale over which significant improvement might be detected is…likely to be far longer than could be detected by comparing one generation with its predecessor”.

It is made clear that “natural selection doesn’t choose genes directly, it chooses the effects that genes have on bodies”.8 There is no sentient decision to evolve “toward” a certain state, evolution does not have goals, it’s a descriptive term for cumulative, adaptive change. Evaluations over whether or not a given mutation was beneficial can only be determined after the fact. Indeed, “‘improvement’… is far from continuous. It is a fitful affair, stagnating or even sometimes going ‘backwards’, rather than moving solidly ‘forwards’ in the direction suggested [by an arms-race]. Changes in conditions, changes in the inanimate forces…are likely to swamp the slow and erratic trends of the arms race…as far as any observer on the ground could be aware.”9

Similarly, when we talk about memetic changes in an evolutionary sense, we can only evaluate the success of a given meme by its survival; any additional judgements or observations might be considered independent, but supporting memes.10

Dawkins writes:

There are patterns of information that can thrive only in brains or the artificially manufactured products of brains – books, computers, and so on. But, given that brains, books and computers exist, these new replicators, which I called memes to distinguish them from genes, can propagate themselves…As they propagate they can change – mutate. And perhaps ‘mutant’ memes can exert the kinds of influence that I am here calling ‘replicator power’. Remember that this means any kind of influence affecting their own likelihood of being propagated. Evolution under the influence of the new replicators – memetic evolution – is in its infancy. It is manifested in the phenomena that we call cultural evolution. Cultural evolution is many orders of magnitude faster than DNA-based evolution, which sets one even more to thinking of the idea of ‘takeover’.11

As with genetic evolution, memes require a habitable environment in which to propagate themselves. In the absence of a suitable environment they eventually become extinct.

First published on Plutonica.net, “On evolution“, on February 09, 2008.

Related Posts Plugin for WordPress, Blogger...Footnotes:
  1. My copy is a revised edition released in 2006. []
  2. p. 43 []
  3. p. 45 []
  4. p. 128 []
  5. p. 112 []
  6. p. 50-51 []
  7. p. 178 []
  8. p. 60 []
  9. p. 181 []
  10. When consciously mutated, we might instead define a new memetic species which can’t properly be identified as being the same as the original meme, except in a tangential sense (think of gross capitalism versus the more specific anarcho-capitalism, for example). []
  11. p. 158 []