This now 35-year-old book was Dawkins’ third, following the famous The Selfish Gene (summary here) and the less-famous sequel The Extended Phenotype (which I still have not read). If the first two were relatively straightforward explanations of evolution and natural selection (and how the phenotype is more than just the genotype), this third book is one of advocacy. He wants people to understand these basic ideas of evolution, and is frustrated that so many still do not (or deny them).
This is one of the first hardcover nonfiction books that I bought, some 10 years after graduating college, when I became more serious about self-education, exploring all the subjects I had never gotten a chance to learn about there.
I bought this book when it came out, from the UCLA bookstore, and read it early in 1987. I even took notes! Rather threadbare, handwritten notes (which I tucked into the book itself, so I still have them). To recapture the book’s ideas, I skimmed through it last month, and expanded my notes.
- The meaning of our own existence has been solved. The problem was that of complex design. Our intuitions about what is probable are tuned, by evolution itself, to work over a span of decades. The solution is slow, gradual, cumulative natural selection, across a geological history we humans have no intuition for.
- Most people still don’t understand the basic mechanism of evolution. It has no purpose in mind, yet it creates the illusion of design; it’s a blind watchmaker.
- The illusion of design is powerful. A common argument against natural selection is the claim that “it’s impossible to believe” this or that could have evolved naturally. But this is the “argument from personal incredulity,” betraying either ignorance or how our intuitions misfire across large timescales.
- Small changes, accumulating gradually, are what natural selection is about. An example is the eye; it might have evolved across 10,000 or more steps, each of some increasing benefit. Those who argue against the idea are those who *want* to believe otherwise (e.g. that it took God), not because the process is implausible, given time.
- Seeds rain DNA; DNA is instructions, algorithms; DNA is ROM, translated via RNA, with an extremely low error rate.
- These mechanisms originated via improbable events across geological time — but improbable events, that we might call ‘miracles,’ can exist without being supernatural. We would have a better idea of how probable or improbable such events are, if we knew whether life exists elsewhere in the universe.
- Genes are selected by how they interact with their environments (which include other genes). There are both “coadapted genotypes” and there are “arms races.”
- The debate (in the 1980s) about the “gradualists” and those who proposed “punctuated equilibria” involved over-simplification for the sake of argument, to pander to the religious, who find evolution distasteful, and partly driven by those merely out to make trouble for a good news story.
- Taxonomy is the science of classification, about the pattern of animals and plants distributed around the world. Many things can be classified in different ways (e.g. books), but evolutionary relationships exhibit a cladistic taxonomy, in which once branches split, they never merge again.
- Alternative explanations for life on Earth, rivals of Darwinism, are doomed; in fact, *only* Darwinism can explain certain aspects of life.
- Conclusion: “Slow, gradual, cumulative natural selection is the ultimate explanation for our existence.”
- This book explains how the mystery of our own existence has been solved. The problem is that of complex design.
- This book is not a dispassionate treatise, but one of advocacy. Not like a lawyer, but because author believes passionately that this is true. (Recalls creationist debater who was just doing it for fun.)
- How did such a simple idea take so long to be discovered? As if humans inherently misunderstand it. One way is that ‘chance’ is misunderstood as ‘blind chance.’ Another is how timescales are radically different; see quote. Another is our own skill as designers.
All our intuitive judgements of what is probable turn out to be wrong by many orders of magnitude. Our well-tuned apparatus of scepticism and subjective probability theory misfires by huge margins, because it is tuned – ironically, by evolution itself – to work within a lifetime of a few decades.
Ch1, Explaining the very improbable, p1, 18p
- We animals are the most complicated things in the known universe. In contrast, physics is the study of relatively simple things. Most people still do not understand the basic mechanism of evolution; it’s not routinely taught.
- The watchmaker is 18th century theologian William Paley. His book was admirable for its time. His example of the watch. Therefore the watchmaker. The example of the eye. Natural selection has no purpose in mind; it’s a blind watchmaker. Hume dismissed the argument from design a century before, but had no alternate explanation.
- So what is complexity? Heterogeneity. Unlikely to have arisen by chance. Contrast Mont Blanc with a Boeing 747. The parts of a 747 have just one arrangement to work, while the rocks of Mont Blanc could be assembled many ways and it wouldn’t make a difference. Most random combinations aren’t good for anything; there are many more ways of being dead than alive. So complication is unlikely to have occurred by random chance.
- Living things, too, obey the laws of gravity.
- What do we mean by explanation? One way to understand a complex thing is to understand it in terms of simpler parts that we already understand. Compare explaining how a locomotive works; we need to understand the details. Each level of component can be broken down further. We call this hierarchical reductionism. No one is a total reductionist, explaining complicated things in terms of the smallest parts.
- [[ This hierarchical reductionism is of course the same basic idea we see later in Carroll and others ]]
- Another kind of explanation is how something came into existence in the first place. What physical conditions need be necessary to allow complex things like elephants to arise? Very few. No deliberate ‘creation’ required. Cf Peter Atkins. The biologist’s job is that of complexity, in terms of simpler things. Consider how Paley would have reacted to a cross-section of the eye, p16.
Ch2, Good design, p21
- The illusion of design is powerful. Examples are bats, with their sonar and radar. Developed long before human engineers understood the ideas. Compare how engineering now would solve the challenges of being a bat. Much detail. How the Doppler principle affects matters. Famous essay What is it like being a bat? P33. Outrage when echolocation first announced, p35.
- Theologians tend to point to things and claims “it’s impossible to believe” such and such could have evolved by natural selection. A book by Bishop Montefiore is a good example of such claims, p37b. It heavily uses the “argument from personal incredulity” p38. Such arguments are weak, often based on simple ignorance. Example about polar bears, 38b. Even when we don’t know the answers to particular examples, that doesn’t prove anything about supernatural design. “We have no intuitive grasp of the immensities of time available for evolutionary change” p39-40. Another aspect is our intuitive notions of probability. Example cuckoo’s nests. Mutation is random; natural selection is not; this seems widely misunderstood. And it isn’t true that each part of a complex system (like the eye) is useless without all the others.
Ch3, Accumulating small change, p43
- Living things evolved through small, gradual steps, each simple relative to its predecessor. This is cumulative selection.
- Note how pebbles on a beach are naturally sorted, by size. Holes will select items that fit through them, from items that don’t. Planets revolve at speeds determined by distance from the sun, not some divine edict. Obviously haemoglobin is enormously complex, and would not have been selected in one step. But in cumulative selection the small changes ‘reproduce’ and are thus subject to yet another sieve. Monkeys bashing at typewriters might produce the works of Shakespeare, but if kind of sieve is applied to narrow the results, it can be done very quickly, pp47-48. Those who think Darwinism is only about chance don’t understand this.
- Another example is a simple computer program to generate shapes via a simple branching algorithm. Recursion. Long example pp51ff. some of the result resemble the shapes of animals!
Ch4, Making tracks through animal space, p77
- More about the eye. Could it evolve in a single step? No. but it can evolve from something slightly different. Is there a series of steps between no eye to eye? Yes, given sufficiently large number of steps. Maybe 10,000, maybe 100,000. Yet some argue not every step would be beneficial. Author notes such arguments are made by people who *want* to believe their conclusions. Anyway most of us wear eyeglasses; are we blind without them? No. Example of a book that makes such arguments, p80-81. Worrying about what 5% of an eye would be good for. Such arguments are again just cases of argument from personal incredulity, p86. Another example is the bombardier beetle. Lungs. Wings. Hearing. 5% of any of these is better than none at all.
- Evolution in fact is evidenced by telling imperfections. Examples. And examples of convergent evolution show that different paths can lead to solutions of the same problems of surviving in the world. Examples on different continents. Quote from EO Wilson, p108.
Ch5, The power and the archives, p111
- When a willow tree pumps seeds into the air, it’s raining DNA. And DNA is instructions, programs, algorithms. As if it were raining floppy disks. This hasn’t already been understood. At one time biology was all about ‘protoplasm,’ a now obsolete concept. Genes are digital technology. It used to be thought it was about blending, like paint. In fact, variation doesn’t go away. The information in genes is chemical. DNA is ROM. Write once, read many times. Arranged along chromosomes. With a sort of addressing system. A translation procedure involving RNA. With an extremely low error rate. This accuracy places a limit on the pace of mutations, and thus natural selection. These mutations are errors, but sometimes in a good way. Much detail; including how RNA is ‘sticky.’
Ch6, Origins and miracles, p139
- How did these mechanisms originate in the first place? Improbable events that we call ‘miracles’ can exist without being supernatural. How improbable they can be depends on the length of geological time. And it’s related to whether life abounds elsewhere in the universe. Does the fact that life exists here, mean it’s common on other planets? But this is just an assumption. It seems medieval to assume ours is the only planet with life… but it’s possible. That would make the luck needed that much greater.
- Typical theories of the origin of life begin with a ‘primeval soup’. Another is the idea that life began in an inorganic substrate, like mud or clay, and then was taken over by the biological. Like scaffolding. Just as one day electronics might take over from the biological. Anyway don’t worry too much about how ‘improbable’ these ideas seem, as if a miracle. Consider what we would call a miracle, the odds. It depends on what we *think* is plausible, and our minds can’t cope with large or small scales of space and time. 160m. And similarly are intuition about probabilities. We assess risks via how natural selection has built our brains, to assess events in the world around us. P162. A much longer-lived alien would have different intuitive notions. We are impressed by coincidences.
- Consider the probabilities of life arising on a random planet, in a galaxy, in the universe, p164. These are the benchmarks we should use.
- [[ So back in the 1986 book we already have discussion of mental biases of scale, how we’re impressed by coincidences, and so on. ]]
Ch7, Constructive evolution, p169
- How natural selection can construct, not only destroy. There are ‘coadapted genotypes’ and there are ‘arms races.’ The first involves genes that aren’t always used, e.g. at different stages of development. Analogous to how ‘deleted’ files on a floppy disk might later be recovered and reused, e.g. mitochondria that descended from bacteria. Margulies and eukaryotic cells.
- Arms races take place across time, as different species evolve to outwit each other. Until a ‘balance of power’ is reached. The Red Queen effect. Example of the heights of trees in a forest. P184. Studies of animals can be done by measuring brain size via EQ, p189.
- So: genes are selected by how they interact with their environments. Including other genes.
Ch8, Explosions and spirals, p195
- Humans tend to over-analogize. From cranks to scientific discoveries. Two analogies that are useful but can be taken too far are: processes that resemble explosions; and the similarity between true Darwinian evolution and cultural evolution.
- The first is about positive feedback. Examples of negative feedback—the Watt steam governor. Examples of positive: temper tantrums; brawls; a nuclear explosion. In evolution: the peacock’s tail and sexual selection. The male’s genes for a bit tail go along with the female’s preference for a big tail. The feedback reaches an equilibrium between the best ‘desired’ state and the most utilitarian state. Much detail.
- Human history is quasi-evolutionary. Trends. Some are improvements, like vehicles, and sound reproduction. Languages evolve in that they change, not necessarily improve. Words degenerate. Pop music is affected by how popular it is. similarly book publishing, etc. Kinds of explosions…
Ch9, Puncturing punctuationism, p223
- About those who challenge supposed ‘gradualist’ schools of history, as if the Israelites really traveled steadily but very slowly for all those years. The challengers say it wasn’t gradual, but in fits and starts. They become very popular. Yet they target a straw-man. The idea began in the study of fossils, which occur in certain predictable orders. Methods of dating. The idea of gradualism can be applied to what we would expect to see in the fossil record, and the ‘gaps’ in the fossil record.
- Eldredge and Gould proposed their idea of ‘punctuated equilibria’ in 1972. But their idea was misinterpreted, deliberately by some, to suggest phases of creation. No actual evolutionist believes this. Still it’s possible there may have been sudden changes in a single generation, e.g. through mutation; these are ‘saltation’ theories. But they should be rejected, p231. They depend on ‘Boeing 747’ macromutations, named after Fred Hoyle’s misunderstanding. Compare simply expanding one model of plane to a larger size: there are still lots of things to change.
- Still, the idea of punctuated equilibria is different. This involves speciation, which can happen when a species is split by some physical barrier, i.e. ‘reproductive isolation.’ These ideas are part of orthodox neo-Darwinism; and it is these that lead to the expectation of ‘gaps’ caused by migration of groups of animals. Eldredge and Gould’ mistake was to claim their ideas were opposed to neo-Darwinism. This played to creationists notions of ‘catastrophism’ and a series of creations. But the evolutionist’s evolutionary jumps still last tens or hundreds of thousands of years – much longer than the sudden catastrophies (like Noah’s flood) the creationists imagine. And Gould’s challenges things that Darwin never exactly said. And so on… example of stasis with the coelacanth.
- So why did the punctuationists *think* they were onto something that challenged Darwin? Likely because of the use of the word ‘gradual.’ Many Victorians clung to the idea of a series of supernatural interventions in the history of life… it strains credulity to think that complex things arose gradually and naturally. And now there are people who simply don’t want to believe in Darwinism: the religious; those who find evolution distasteful; and those who just like to see applecarts upsets for a good news story. Thus the news media will seize upon any apparent controversy with orthodoxy.
Ch10, The one true tree of life, p255
- About taxonomy, about the pattern of animals and plants distributed around the world. The science of classification. Many things can be classified. For books, for example, there is no one correct way. Yet the one unique system is based on evolutionary relationships—this is the cladistic taxonomy. Hierarchical in the sense that once branches split, they never merge again. Or ‘perfect nesting.’ Such patterns don’t work for books. This implies that intermediates – like those imagined by creationists – not only don’t exist, but cannot exist. OTOH there are intermediates looking back at extinct animals. (Aside about speciesism re human embryos and animals like chimps, 262-3.) And discussion of ‘species selection’ p265. [[ This sounds like a precursor to group selection. ]]
- Evolutionary convergence can make cladistic evolution difficult. Molecular studies reveal similarities…. Etc, family tree p273.
- For some reason taxonomy is especially ill-tempered a biological field. Some branches are focused on evolutionary relationships; others on patterns of resemblance in their own right. The first group is also split: the cladists; and the traditional. Examples of how these would work. Ways to calculate average resemblance. Some don’t consider the idea of ancestor. Some go so far as to suggest that taxonomy shows something’s wrong with evolution itself, p283. Actually it may be true that evolutionary considerations are unneeded for taxonomy; but that doesn’t make evolution false. Of course those who say such things get lots of attention from creationists, p284.
Ch11, Doomed rivals, p287
- There have been numerous rival theories to Darwinism, but not only can we show the lack of evidence for them, we can show the *only* Darwinism can possibly explain certain aspects of life.
- Author predicts if alien forms of life are discovered, they will have evolved through natural selection.
- What does explain life mean? One explicable only through Darwinian selection is adaptive complexity, 288m. Author is using the example of the eye. We’ve seen how Darwinian principles explain the development of the eye.
- Consider Lamarckism. Lamarck had the idea of evolution, but got the mechanism wrong. His errors were the inheritance of acquired characteristics, and the principle of use and disuse. The first was folk wisdom. It’s all about striving. Some people *want* it to be true. Shaw, Koestler. Lysenko. No evidence for such a thing has ever been found. But Lamarckism isn’t even plausible; digression about embryology, the idea of the homunculus. DNA is not a blueprint or miniature body; it is a recipe, a set of instructions. P295. Details. The idea of inherited characteristics is plausible if DNA were a blueprint; a change in the latter would affect the former. Even if it were true, it couldn’t explain adaptive evolution. One problem is that many acquired characteristics are not improvements. Injuries; learning. Details.
- Other rival theories. “neutralism” and “mutationism”. Details. The latter idea proposed that only mutations drove evolution. But how does that result in improvement? This gets tied up with the ways mutations are or are not ‘random’. Details of a caricature of Darwinism, p309.
- Another rival is the ‘molecular drive’ p312 in which most evolutionary change is not adaptive. Details; it would never work because all the possible branches of a chain of 1000 branches would be too many.
- The oldest rival to natural selection is that of creationism, of a conscious designer. Some consider evolution ‘guided’ rather than the result of instantaneous creation. But these beliefs are superfluous, and they assumed the complexity they try to explain. The deity must have been vastly complex in the first place. If we assume that, why not just assume the existence of life by itself?
- Summary p317. “Slow, gradual, cumulative natural selection is the ultimate explanation for our existence.” 318.
As I reread/skimmed this book, I realized that it was this book that first provided me two ideas that have lingered.
The first is the idea of “personal incredulity”. You can’t tell what is true or not just because it fits, or does not fit, your intuitions.
The second is how DNA isn’t a blueprint, but a recipe. This is profound; think it through. Evolution built DNA as a series of steps to build a body, extra steps were added through mutations. Some worked, many different, but the original recipe wasn’t changed. Thus ontogeny recapitulates phylogeny. Thus all the “junk” DNA, which apparently are sequences of earlier recipes that have been disregarded in favor of new ones. And so on.
I explore this idea in my recent post about why symmetry, which would be an amazing effort for a blueprint author (to make something so exactly equal on two sides, or more), is easily explained as a recipe.