The Greatest Show on Earth: The Evidence for Evolution – Richard Dawkins

Thoughts: This book’s decent, but not without its warts. While there were some novel examples of phenomena I was already familiar with, it was only in the book’s last chapter that I came across any new concepts. Throughout, Dawkins never missed an opportunity to take a swipe at creationists, a tendency I would have been happy without. And he would occasionally dig in his heels on oddly specific points: for example, defending his desicion to refer to the Peking Man as such (Peking, evidently, is an old anglicization of Beijing) in a substantial footnote. Overall, I took almost as much from the book as an example of Dawkins’s writing/rhetorical style (he’s intelligent and his theories make sense, but I can see why he’s a polarizing figure) as from the content itself.

(The notes below are not a summary of the book, but rather raw notes - whatever I thought, at the time, might be worth remembering.)

Dawkins, Richard. 2009. The Greatest Show on Earth: The Evidence for Evolution. Free Press.

Chapter 1. Only a Theory?

• Draws the comparison between a biology professor having to spend the first few lectures of a course working to convince their students that natural selection happens, and a classics professor having to convince their students that the Roman empire existed

Chapter 2. Dogs, Cows and Cabbages

• 36: Neoteny, the tendency of adult organisms to retain the proportions of infants in certain body parts.
  • aka allmetric growth - different body parts grow at different rates.
  • Opposite is isometric growth, where an adult is just an “inflated” version of the infant. Very rare in nature.
• 39: Looking at all the ways dogs have been shaped by selective breeding, Dawkins asserts that, despite its moral odiousness, eugenics is practically possible. “Who would have thought, for example, the dogs could be bred for sheep-herding skills, or ‘pointing’, or bull-baiting?”

Chapter 3. The Primrose Path to Macro-Evolution

• 51: Insects don’t see the red part of the light spectrum. If you come across a tubular flower that’s red, it’s almost certainly pollinated by birds.
• 62f: The subtitle of On the Origin of Species is The preservation of favoured races in the struggle for life. Dawkins states that “races” should not be interpreted phylogenetically (i.e. race = all the organisms that share a common ancestor) but based on their features (i.e. ‘a group or class of people, animals, or things, having some common feature or features’ from OED). Had Darwin known about genetics, Dawkins opines, Darwin might have written ‘all those individuals who possess a certain allele’
• ~73: Dogs may have partly domesticated themselves before humans began to domesticate them. Decreased ‘flight distance’ was probably selected for as human settlements became potential sources for food, as dogs navigated the risks and rewards of scavenging and being attacked by humans.
• 74-75: Belayev’s silver foxes - bred them by selecting for low flight distance. After only six generations, Belayev needed to create a new category to account for exceedingly tame foxes, and by the 35th generation, 80% of the foxes were in the “domesticated elite” category
  • this happened really quickly! 35 generations is practically nothing in geologic time
  • this is a big effect size!
  • 75-76: without specifically selecting for it, the foxes came to have many of the same traits familiar from domestic dogs: piebald coats, upturned tails, floppy ears…

Chapter 4. Silence and Slow Time

• 90: by lining up tree rings of older and older trees in different regions, dendochronology can be used to date wood as far back as ~11,500 years

Chapter 5. Before our Very Eyes

Chapter 6. Missing Link? What Do You Mean, ‘Missing’?

Chapter 7. Missing Persons? Missing No Longer

• 207: the proportions of the heads of infant chimpanzees are very similar to those of infant humans (and somewhat, to adult humans), but the muzzle grows significantly over the course of a chimp’s life. “It seems highly plausible that, as Australopithecus evolve through various intermediates to Homo sapiens, shortening the muzzle all along the way, it is so by the obvious route of retaining juvenile characteristics into adulthood. In any case, a great deal of evolutionary change consists of changes in the rate at which certain parts grow, relative to other parts.”

Chapter 8. You Did it Yourself in Nine Months

• 224: after trying out several analogies for the growth/development of organisms, such as sculpture, assembly line, Dawkins proposes a metaphor that he feels comes pretty close: origami. A folded piece of origami goes through several intermediate (/‘larval’) stages before it reaches its final form. The paper can’t be cut, and you can’t stick anything to it. And folding instructions are a bit like the instructions found in DNA: “You are following a set of folding rules that seem to have no connection with the end product, until it finally emerges like a butterfly from a chrysalis”
  • limitations, however: embryos generally grow as they develop (perhaps a better metaphor would be “inflating origami”), origami requires human hands to fold it, while an embryo assembles itself.
• 236: Mentioned, in regard to bi-stable switch molecules and their roles perception etc. Jacques Monod’s Chance and Necessity (prions are an example of bi-stable molecules that go wrong)

Chapter 9. The Ark of the Continents

• 267: the cichlids of Lake Malawi/Lake Victoria: the water level in Lake Malawi fluctuates widely over the centuries/milennia, and includes many islands and submerged hills. When water level was low during the 18th century, many of these islands/hills were connected to the mainland. When water levels rose, these hills became ‘archipelagos’ of habitats, each supporting its own semi-isolated population of cichlids, which contributes to the species diversity in the lake
  • lake Victoria is believed to have been entirely dry around 17000 years ago. The 450 endemic species of cichlids must have speciated since then

Chapter 10. The Tree of Cousinship

• 304-305: Dawkins raises one possible (though unlikely, in his view) downside of genetic modification: future studies of evolutionary relationships may be hampered, since genetic drift may be a less accurate measure of evolutionary distance.
• 306-307: crustaceans are segmental, with a pair of appendages coming out of each segment. The middle segments are generally involved in walking (becoming legs, claws etc), though the first 5 segments make up the head (some appendages forming antennae, others mandibles, etc.)
• 317-318: when people say “humans and chimps share 98 percent of their genes”, it’s actually a measure of how strong the bonds between strands of DNA are, are when strands of human and chimp DNA are combined in a PCR test. Otherwise, there’s ambiguity about whether the two organisms share base pairs (would lead to high sharing percentages) vs sharing codons (which would lead to lower percentages) vs sharing entire genes verbatim (which would lead to a much lower percentage)

Chapter 11. History Written All Over Us

• 345: the kakapo, New Zealand’s flightless parrot. Flightless, but it hasn’t yet lost its instinct to fly. Quoting Douglas Adams’s Last Chance to See: “Apparently a seriously worried kakapo will sometimes run up a tree and jump out of it, whereupon it flies like a brick and lands in a graceless heap on the ground.”
• 366-367: Teleosts (basically, all fish except sharks) have ancestors that sometimes breathed air using lungs - adapted from a cavity in the gut, rather than adapted from a gill chambers. Now, these proto-lungs are used as swim bladders.
  • swim bladders are cool - if fish want to rise higher in the water column, they take dissolved gas molecules from their bloodstream and add them to the swim bladder, increasing their volume. When they want to descend, they take gas from the swim bladder and dissolve it back into their blood.
  • j: looking at wikipedia, it seems that Teleostomi, which include all jawed fish except for sharks and placoderms (armored fish), evolved this proto-lung. Tetrapods evolved from Teleostomi, while Teleosts use the proto-lung as a swim bladder
    • this explains why tetrapods can choke on their food - their respiratory tract is intimately connected with their digestive tract
    • Dawkins states that the Anabas, which is within Teleostomi but not within Teleostei, actually use gill chambers as lungs

Chapter 12. Arms Races and ‘Evolutionary Theodicity’

• 383: Often, intraspecies competition plays a greater role in evolution than interspecies competition. “When a cheetah chases a herd of gazelles, it may be more important for an individual gazelle to outrun the slowest member of the herd than to outrun the cheetah”

Chapter 13. There is Grandeur in this View of Life

• 402: argumentum ad consequentiam (fallacy) - “X is true (or false) because of how much I like (or dislike) its consequences”
  • j: does this conflict with Sean Carroll’s assertion that if a proposition leads to a paradox (e.g. Bolzmann Brain) that we can assign it a low prior credence and just get on with things?
• 406: different ways that information about the past is archived to improve fitness into the future (he calls these the ‘four memories’):
  • DNA
  • immune system
  • nervous system (learning/literal memories)
  • culture
• 409: why do all organisms share the same key for decoding DNA? Francis Crick suggested that if there was a change in the encoding for one amino acid, a whole range of proteins would suddenly change, likely with catastrophic consequences
  • cf. path dependence - as soon as there was a system that worked well enough, it quickly became ‘baked in’
  • cf. entropy - there are many more ways to make things worse than to make things better
• 416: natural selection is an ‘improbability pump’ - “a process that generates the statistically improbable”
  • to check out: Dawkins’s book Climbing Mount Improbable
  • j: cf. life, shaped by evolutionary processes, is a small eddy in the large entropic stream of solar radiation that is flowing from low entropy to high entropy.
• 422: should we be looking for a likely/plausible theory for the origin of life? Considering we don’t observe much life when we look out into the universe, Dawkins argues that the origin of life is almost necessarily unlikely
• 423-424: Dawkins suggests that some clades become widespread because their body plan and embryology is easily shaped by evolution. “some embryologies must be better than others at evolving…. A case can be made, that there might be a kind of higher-level natural selection in favour of ‘evolvable embryologies’”. He connects this with George C. Williams’s idea of clade selection