The Greatest Show on Earth

Notes on Chapter 3: The Primrose Path to Macro-Evolution

• Like human-influenced artificial selection, the history of flowers also teaches us about evolution
• Wild roses were (genetically) sculpted by the human eye into the varieties we have today, but insects were the first domesticators of flowers
• Russians bred giant sunflowers, before that sunflowers had already been cultivated by native Americans, which made them larger than wild sunflowers, and before that, all brightly colored flowers owed their existence to insects (and other domesticators, such as birds, etc.)
• To take advantage of sexual reproduction, flowers need cross-fertilization
• Many plants use wind as a mechanism for pollen transportation, but this method requires a large production of pollen
• Plants use nectar as a bribe for pollen transportation
• n Madagascar, there is a long-tubuled orchid which prompted them to predict there existed a moth with a tongue long enough to reach the nectar.  Such moth was later discovered.
• Insects see the color red poorly ... most red flowers we see are pollinated by birds, not insects
• nsects sight is shifted toward the ultraviolent spectrum, which humans can't see
• The color of flowers has been shaped by the eyes of insects
• Insects and flowers have a symbiotic relationship.  Flowers breed insects to be good transporters of pollen.  Insects breed flowers to be reliable producers of food.  They therefore co-evolve together.
• Another example of natural domesticators: brightly colored male birds, caused by 'sexual selection'.  Females choose males which they find most attractive.  Females remain plainer and more naturally camouflaged.
• The heikea japonica crab shell has a pattern which bears the resemblance of a samurai warrior.  Carl Sagan thought it was caused by human selection (fishermen threw back the crabs with the most resemblance).  Dawkins thinks it is just a coincidence.
• There is a caterpillar with a tail that looks like a snake
• Deep sea angler fish use bioluminescent tail as bait to catch fish; in a sense prey fish "choose" (inadvertantly, of course) which angler fish survive
• Choosing agents are unnecessary ... survival itself acts as the selector.  All other examples previously given are simply special cases of the general phenomenon
• Discussion of how we can test evolution by experimentation
• Since 1896, agronomists have experimentally create two lines of maize, one with very high oil content, and one with very low content, both starting with the same variety from 1896
•  Rats have been experimentally bred in the lab to be more resistant to tooth decay
• A good discussion of evolutionary tradeoffs follows.  Example, antelopes with longer legs run faster, but are more prone to fracture.  Life forms reach equilibriums based on tradeoffs needed.
• Foxes have been experimentally bred to be tamer
• A discussion of various tricks flowers use to fool insects into transporting their pollen
• Various experiments have shown that dramatic changes can occur in very short timeframes; nature can do the same work, but needs more time; has there been enough time for evolution to work?  This question will be addressed in Chapter 4.

Kevin's Commentary on Chapter 3

In this chapter Dawkins shows us that human eyes are not the only eyes that act as selecting agents.  Insects select brightly colored flowers by choosing them for their attractiveness and their nectar, and female birds choose male birds they find attractive, thus causing males to become more brightly colored over time.  Finally, Dawkins reveals the full lesson of evolution, that you don't even need eyes, human or otherwise, to act as the selecting agent, that mere survival will do the job.  And that is what evolution by natural selection is all about.

I understand his argumentation fully.  Unfortunately, I think the argument will do nothing to convince those that are determined to deny evolution.  I've heard creationists use some of these same facts as evidence for their point-of-view.  For example, I've heard an argument that says the existence of vanilla orchids and vanilla bees proves an act of special creation.  Since one cannot exist without the other, it must be that a deity created both simultaneously.  Such a fact is easily explainable via co-evolution, but that is even harder for people to fathom.

The experiments discussed are compelling, so I hope that, dare I say, ahem, "non-believers", will be persuaded by them.