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Chapter 6 Evolutionary Biology

• "In biology, you should never believe your disbelief." [p. 148]
  
  
• "My grandfather was the one who first taught me about evolution. He taught me to respect evidence and to remember that religion must always accommodate reality. We live in the real world, he said, and we must understand the world on its own empirical terms." [p. 149]
  
  
• "It doesn't matter what disk you insert in the mental module called 'God'. None of it will suffer if you see the principle underlying and interlocking all earthly life. The life we see around us, the life we call our own, evolved from previous life forms, and they in turn descended from ancestral species before them." [p. 150]
  
  
• "Evolution by natural selection is an absolute principle of nature, it operates everywhere ..." [p 150]
  
  
• "... among scientists, the matter is as settled and straightforward as I made it sound. You release your glass, it falls to the ground. You gaze out at nature, evolution all around." [p. 152]
  
  
• " 'It's often said that because evolution happened in the past, and we didn't see it happen, there is no direct evidence for it', he [Dawkins] said. 'That, of course, is nonsense. It's rather like a detective coming on the scene of a crime, obviously after the crime has been committed, and working out what must have happened by looking at the clues that remain. In the story of evolution, the clues are a billionfold.' " [p. 152]
  
  
• " 'There are clues from the distribution of genes throughout the animal and plant kingdom, he [Dawkins] said, and from detailed comparataive analyses of a broad sweep of physical and biochemical characteristics. 'The distribution of species on island and continents throughout the world is exactly what you'd expect if evolution was a fact,' he continued. 'The distribution of fossils in space and time are exactly what you would expect if evolution was a fact. There are millions of facts all pointing in the same direction, and no facts pointing in the wrong direction." [p. 152]
  
  
• "A scientific theory, like Einstein's theory of general relativity, like the theory of plate tectonics, like Darwin' theory of evolution, is a coherent set of principles or statements that explains a large set of observations or findings." [p. 154]
  
  
• "This is a scientific 'theory': not a hunch, not even a bunch of hunches, but a grand synthesis that gathers 'facts' or robust findings ... and infuses them with meaning. A scientific theory also has predictive power. Under its rubric and tutelage, you can generate new ideas about how the world works , and then put those ideas to the test." [p. 154]
  
  
• "Yet no matter how they swat the details, evolutionary scientists do not dispute the fundamentals." [p. 158]
  
  
• "Through mutations and DNA shuffling, discrepancies arise in the gene pool that give nature something to select from. Now nature has choices among the plethora of offspring; let the winnowing begin." [p. 159]
  
  
• "Natural selection, then, is a two-step exercise of almost unlimited potential. First, minor inherited variations arise in a population by chance." But some of the variations are beneficial to survival and so are perpetuated in the gene pool. [p. 159]
  
  
• "Genetic quirkery can also sow biodiversity. If a mutation happens to affect a key gene that controls an animal's basic development, the resulting aesthetic or behavioral changes may be so profound that beneficiary of the mutation looks or acts like a whole new species." [p. 162]
  
  
• "Several hundred thousand fossil species have been identified and named, but researchers suspect that the known bones represent a mere one-thousandth of one percent of all species that have lived." [p. 163]
  
  
• "Moreover, there are some beautiful fossil series that show persuasive procession of one species into the next." (e.g. the horse and homo sapiens). [p. 165]
  
  
• "... the clustering of closely allied species on the same land masses and the discrepancies between the inhabitants of one continent and those of another, can be traced back to one elegant explanatory engine ... simple inheritance." [p. 168]
  
  
• The taxonomic system itself supports an evolutionary interpretation. Most things can be organized in a multitude of ways, but organisms lend themselves to just one system: kingdom, phylum, class, order, family, genus and species. (Kings pour coffee on fairy god-sisters)" [p. 168]
  
  
• "... not every feature on a creature is the product of natural selection. Some may be residual traits that are no longer needed or functional, but that are harmless and so are not under selective pressure to be tossed off." [p. 174]
  
• "A still greater engine ... of conspicuous traits that may do nothing to increase an individual's life span and in some cases help clip it short, is the evolutionary force called sexual selection. (e.g. the male peacock's tail, antlers of elk and deer) [p. 174]
  

Chapter 7 Molecular Biology

• "We know that all cells on Earth are monophyletic, are all descendents of a single founder cell, rather than being polyphyletic, of mutiple independent origins, because the unity of the genetic code tells us so." [p. 187]

• "A cell is the basic unit of life, and the smallest unit of matter that can ... be considered alive." [p. 187]
  
  
• "A cell has three basic parts to it: a greasy, waterproof outer membrane ...; a gooey inner part ...; and a cache of DNA ... enclosed in a nucleus." [p. 188]
  
  
• "Why build bodies ... of parts too tiny to see? ... To be small is to have control. ... Small is manageable. Small is flexible. The cell is shileded from its environment and so can control what happens inside in a way it cannot control the world outside." [p. 189 - 190]
  
  
• "Understanding the cell means understanding proteins, and this brings us to a minor point that many biologists admitted they find persistently frustrating: the public's narrow idea of what a protein is." [p. 191]
  
  
• "Technically, a protein is a string of amino acids, distinctive clusters made primarily of the elements most strongly associated with life - carbon, oxygen, hydrogen, and nitrogen - arrayed in a style that lends each amino acid a little knob of positive charge and a little knob of negative charge." [p. 192]
  
  
• "Far more imprtant than a protein's size is its shape, how its chain of amono acids folds, curls, puckers, and zags in three-dimensional space." [p. 193]
  
  
• "What is it that proteins so busily, prodigiously do? Most of them are enzymes, proteings that help activate or accelerate chemical reactions in the cells by bringing together ingredients that might otherwise remain separate." [p. 193]
  
  
• "DNA is a molecule ... in a supercompressed state ..., still DNA is hundreds of times the size of an average protein. Yet for all its bulk, DNA is ultimately a simple molecule, far simpler, in fact, than many of the proteins that surround it." p. 198]
  
  
• "... proteins are constructed from twenty different amino acids, DNA ... is composed of only four different modules (cytosine, guanaine, adenine, thymine: C,G,A,T), called bases.
  
  
• "... key chemical sequences in the DNA that encode the body's proteins are called genes." [p. 199]
  
  
• "... the average cellular protein survives only a day or two..." [p. 204]