The Greatest Show on Earth. By Richard Dawkins

The Greatest Show on Earth

Richard Dawkins

Black Swan. First published 2009.

Dawkins addresses this book to those who would like to see what evidence there is for the theory of evolution. Not the people who would deny the fact of evolution, for they are not going to change their mind, no matter how much scientific evidence is presented. But for people who have learnt about the theory, and believe it to be the truth, but are not able to comfortably reply (in their own minds or in debates) to the various challenges put forward by the 'evolution-deniers' - I won't just say 'creationists', there are other varieties as well. Dawkins presents various different strands of evidence, some of them more convincing than others; some known to Darwin, others made possible only recently. He also presents detailed evidence for ideas that are not actually part of Darwin's theory, but necessary for it, such as a very ancient origin for the Earth.

Dawkins does not here present the theory in any great detail. He has already done so in several other books. (His tone in the one or two of those books that I have read is as polemical as in this one. This tone makes the book lighter reading than it would have been, had it been more academic.). I have repeated Daniel Dennett's summary of Darwin's idea elsewhere in this blog, and can do no better than copy and paste from there, as follows: Evolution by natural selection occurs whenever the following conditions exist: (1) variation: there is a continuing abundance of different elements. (2) heredity or replication: the elements have the capacity to create copies or replicas of themselves. (3) differential "fitness": the number of copies of an element that are created in a given time varies, depending on the interactions between the features of that element and features of the environment in which it persists. Variation occurs randomly, without any 'intent'. Natural selection imposes different survival rates for different variants. The ones that fail in this process disappear, and only some of variants are replicated in the next cycle. If this procedure is repeated a sufficient number of times, the original single entity differentiates, over time, into a variety of different species. This Darwinian process, can, in principle, explain all the immense diversity found in nature, not just the biosphere, but inanimate systems as well, and, in practice, all the biological diversity, and an overwhelming number of non-living systems.

Of course, just because a procedure or a process (i.e. a theory) is self-consistent and logically flawless does not mean that's how things actually happened. For that to be established, in other words for the theory to be accepted as a scientific fact, in the manner, for example, in which Newton's Laws of Motion are accepted, we need observational and experimental evidence. We also require that the theory has some predictive power - the more this power, the more scientifically powerful the theory, more it is the 'truth'. 

Dawkins addresses the first of these issues very effectively in this book. The subtitle - 'The Evidence for Evolution' - is a clear statement of intent. And he carries out this intent with surely and competently, by laying out all the observational evidence there is for the theory. Here is summary of what he discusses.  

• He starts from where Darwin also started, with descriptions of dog-breeding, horse-breeding, pigeon-breeding, and so on, which establish that it is possible to use a selection mechanism to speed up the widening of differences between variants of an animal, until it results in two types that are so different that they cannot inter-breed, and may be considered two independent species. Selection by humans, of course, has not lead to different species, not as yet. But, would a dachshund be able to cross-breed with a St. Bernard? Only with great difficulty, I should imagine. 

• Dawkins then describes evidence for non-human selection, i.e. natural selection. Flowers are selected for their visual attractiveness and perfume by bees and butterflies and wasps. In their turn, the insects evolve to match the flowers. These processes drift into speciation, and new species of flowers and insects arise, matched for each other. Dawkins describes a variety of orchid in Madagascar that has a long and narrow approach to its nectar. To Darwin and (Alfred Russell) Wallace (co-discoverer of the Theory of Evolution by Natural Selection - ToEbNS), this implied the existence of an insect with a long and narrow proboscis. And years later a moth with precisely the required characteristics was discovered. So yes, Darwin's theory had predictive value, as well, though admittedly this prediction did not have the same force as predicting the bending of starlight, or the existence of the positron.

• The immense amount of time required to achieve the observed species diversity argues for an ancient origin for the earth, and this is supported by multiple lines of evidence - radioactive dating being the most prominent and rigorous of these. 

• Speciation happens all the time, sometimes in comparatively short periods of time. This has been observed in the wild - lizards on two islands of the coast of Croatia that, in a few decades, evolved with distinctly different mouths to take advantage of the geographical differences in the vegetation; and white moths in pre-industrial England that turned black to better camouflage themselves in the newly soot-laden landscape. Rapid speciation has also been observed in, for example, bacteria, in laboratory experiments where they were artificially selected for a particular trait. And of course there is the fearsome advent of MRSA, though Dawkins does not talk about it. This is a strain of lethal bacteria that is resistant to most known antibiotics, and has probably arisen only in the last few decades. 

• There is a large amount of fossil evidence which traces the different stages of evolution of many different animals. Human evolution, from 'Lucy' about a million years ago, in particular, is known in quite amazing detail, and though new fossils are being unearthed all the time, the broad outlines of the evolutionary road human beings took to get here are already well understood and well supported. Claims of 'links' being 'missing' are false. [In discussing fossils, Dawkins presents a partial transcript of an interview he had with Wendy Wright, a Christian creationist. Her utterly stupid attitude in refusing to acknowledge the evidence and the facts, and on insisting that evolutionary scientists are aggressively and wrongly promoting their 'beliefs', and that other beliefs - e.g. creationism - are equally valid, all this reminds me of the 'arguments' presented by some of my friends, highly educated guys with impressive degrees, when they say global warming along with the consequent climate change is 'hogwash'.] 

• Speciation of a sort occurs in each individual organism as it grows and develops from a single cell into a complex multicellular organism. Dawkins uses this chapter to to emphasize that though this process is near miraculous, it can be explained as arising from local independent interactions between molecules that give rise to all these marvelous structures and functions - in other words, no 'skyhooks', in Daniel Dennett's words.

• The theory of the drifting continents - plate tectonics - explains the geographical distribution of the species, and thus supports and underscores the theory of evolution. [There is independent evidence from geology for continental drift - and independent evidence for evolution. And, though the one is not proof of the other, the two theories match and complement each other well.]

• Skeletal and anatomical structures have similar or related features across species and genera, clearly derived from a common prototype (though they could equally have been derived one from the other - there is other evidence to show that such similarities are not descended one from the other, but both come from a common predecessor). However, many cases of such similarity are due to convergent evolution, rather than divergent evolution from a common ancestor - the wings of birds and bats are an obvious example of convergence. Dawkins also describes the DNA evidence for evolution. Large scale genome sequencing projects have produced, and continue to produce, rich data. And, with the data and the software widely accessible, gene sequence comparison makes it possible for any interested person to sit at a home computer and verify evolutionary relationships between species. Here, as elsewhere in his writings, Dawkins takes a strict gene's-eye view of biology, with inheritance coded for only in the DNA. He is dismissive of the possible role of horizontal gene transfer, which has been identified to be significant for evolution not only in prokaryotes (bacteria) but also in eukaryotes (higher organisms, plants, animals). I think he does not sufficiently emphasize that the presence of a universal genetic code, across all forms of life, from viruses to bacteria to plants to animals, as the single most important validation of the idea that all species on earth originated from a single, unicellular form of Life which existed about 4 billion years ago.

• In a polemical chapter, aimed more at striking down 'intelligent design' and creationism, Dawkins points out that there are several unnecessary complexities in animal anatomies that make it clear that evolutionary 'progress' is a random walk in biological space, natural selection favouring one particular direction at one moment, and another at the next. One such extraordinary and needless feature is the fact that the laryngeal nerve, which connects the larynx to the brain, actually first goes down from the larynx into the thorax, before coming up again to connect to the cortex, which is a detour with no function. This oddity, and a couple of others, are presented by Dawkins as examples of 'unintelligent design'. Dawkins strikes another blow against creationism by pointing out to the unspeakable cruelties that take place in nature that is 'red in tooth and claw'. He refers to the Ichneumonid wasps that are parasitoids. To quote from 'http://northernwoodlands.org/articles/article/giant-ichneumon -wasp', "Typically, an adult female parasitoid lays an egg on the surface of or into the body of a living larva of another insect. When the egg hatches, the parasitoid proceeds to systematically consume the host. Like a cat with a mouse, it keeps its victim alive as long as possible. Dead larvae rot quickly, and this ruins the meal. First the parasitoid eats the fat bodies of the larva, then the digestive organs, keeping the heart and central nervous system intact for as long as possible. Finally, these are consumed as well and the long-suffering victim dies, leaving an empty caterpillar shell in which the victorious insect may choose to pupate." Dawkins quotes an un-named Australian scientist as saying that whoever 'designed' such a creature must be 'sadistic bastard'.

• Dawkins also provides evidence for the mindlessness of evolution by pointing out to the constant strife to appropriate a greater and greater share of the resources, and to always try and become 'better' - better at chasing prey, or better at escaping the predator, or sometimes both. He hints at a social connection to Darwinism here by making a parallel between natural selection, which he says 'chooses between rival individuals within a population', and Adam Smith's 'invisible hand of the market'. I am not sure how much this comparison is valid. The analogy could easily feed a bleak view of human society where success and 'progress' are not predicated on ethics. But, Chomsky, for example, has a different take altogether on what exactly Smith said and meant. It is overly simplistic, invalid and even stupid, not to say dangerous, to extend Darwinism into social interactions, especially in order to justify a specific point of view.

The book, as I mentioned in the beginning, appears to be written mainly to provide talking points to those who would refute the idiocies of the creationists. It is an excellent read, and this edition is supplied also with many beautiful illustrations. The explanations are rigorous, comprehensive and crystal clear. But it is unlikely to actually change the minds of to many creationists. They, like climate-change deniers or Hindutvawadis, or for that matter, believers in many other types of theories and systems - religious, economic or political - will not let facts come in the way of their 'truth'. (Talking about religious beliefs, I may mention that atheism is not a belief - it is based on logical deductions from the lack of evidence for an anthropomorphic, omnipresent, omnipotent God).