Chapter-by-chapter thoughts on Richard Dawkins’ The Greatest Show on Earth: The Evidence for Evolution
by John C. Snider © 2009
Chapter 3: The primrose path to macro-evolution
As I had hoped/suspected, Dawkins turns his attention from artificial selection to natural selection. Unfortunately, I have a slight problem with the way he introduces it. He starts by pointing out that there is evidence that plants (namely flowers) have influence the evolution of insects and birds, and vice versa. But he falls into a trap that has plagued many an evolutionary biologist speaking to general audiences, and that is in the unintentional implication of intent in the effect one species of plant or animal has on the evolution of another.
Properly speaking, things don’t evolve, they are evolved. Giraffes don’t evolve long necks in a desperate attempt to reach the utmost branches; rather, proto-giraffes with incrementally longer necks held an inherent survival advantage over their shorter-necked kin, and over the millennia what we think if as giraffes were evolved out of that iterative, unintentional process.
So, when talking about the relationship between flowering plants and insects, and the evolutionary relationship between them, Dawkins doesn’t, for example, say that plants whose flowers happened to have sugar-bearing nectars naturally attracted insects, and so gained an inherent survival advantage over their less-sweet kin who had to rely solely on the wind to pollinate them. Instead, Dawkins talks about plants using a “bribe of food,” which to me sounds too much like intent on the part of the plant, as if they were nervous debutantes plotting how to attract a suitor, when in fact it’s just mindless, unguided happenstance. Dawkins even describes flowers “[guiding] bees in to land by little runway markings, painted on the flower in ultraviolet pigments,” when actually, he should have been more explicit that flowers which happened to have certain kinds of markings were favored by bees, and so over the years those plants gained a survival advantage. Instead, it sounds like flowers have a night crew out painting a runway.
That’s not to say Dawkins is peddling intentional evolution–far from it. It’s just I think he could have been a little clearer in spelling out how it’s a blind, unguided process that nonetheless can be shown to yield certain results. (I should say I particularly liked Dawkins’ skeptical approach to the “urban legend” about how the Heikea japonica crab developed its uncannily face-like carapace–a folktale that apparently suckered both Sir Julian Huxley and Carl Sagan.)
Dawkins goes on to discuss sexual selection, although he (perhaps wisely) doesn’t get bogged down in what scientists think about why, for example peahens like a certain kind of peacock. But the fact that peahens have specific proclivities has undeniable shaped, or colored, the peacock we see today.
Overall, not a bad chapter, but I still think Dawkins, although he comes around to it in the end, could have been a little clearer in explaining the unguided nature of evolution.
The Greatest Show on Earth is available at Amazon.com and Amazon.co.uk.
Read my thoughts on Chapter 2.
Read my thoughts on Chapter 1.
This is a pet peeve of mine in evolutionary writing: referring to cause/effect chains as if they were intent/outcome chains. I’d call it “the intentional fallacy”, but that’s already taken by literary criticism — I don’t know what the proper name is. While it’s perfectly ok in colloquial English to say “the lightning wants to hit the highest point”, it’s ill-advised when talking about something that people misunderstand as badly as evolution.
I appreciate your comments and do like the format – I look forward to more reviews done this way. However, in this case, so far it has somewhat put me off wanting to read this particular book!
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In The Selfish Gene, Dawkins uses similar “intention-like” language, but takes great pains to frequently point out — I would estimate about twice a chapter! — that he is not literally referring to an organism’s intention, but using at as a shorthand for actions which will lead a gene to propagate itself most effectively.
It at times gets a bit tedious (yes, yes, I know already!) but it also may be a damn good idea — both because laypeople and denialists can get the wrong impression, and also because even some of the luminaries of evolutionary biology have occasionally lapsed into lazy intention-based thinking as a result of overuse of the metaphor.
From what you say, it seems in this book he has chosen to be less pedantic, at the cost of perhaps being more likely to be misunderstood. Tough call, I’d say…
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I agree fully about the “intention” language. Once you start to notice it, it seems you hear it everywhere. Evolution occurs in ecosystems, not just in species. The species in an ecosystem co-evolve, or are co-evolved if you wish, slowly optimizing as a system, not even as individual species. Not to preach… I object to “intention” language especially among people like Dawkins because it spreads, allowing more and more lazy thinking as it goes.
Dawkins has a wonderful way of explaining things and “bribe of food” is a way of relating the point to human beings. Ultimately it IS a bribe. He makes the important points of what drives evolution all over his books. I can’t imagine anyone is going to think the plant is literally bribing an insect after reading his book.