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→But, but, but...!: unsigned and reply re speciation.
"But speciation happens all the time!" Sure, it does--but only within definitely prescribed kinds. You don't get a new species that is a cross between a wolf and a big cat--nor could you produce a viable pup/kitten hybrid by crossing any species of wolf (the domestic dog is a subspecies of the gray wolf ''Canis lupus'') with any species of big cat.
"But speciation happens all the time!" Sure, it does--but only within definitely prescribed kinds. You don't get a new species that is a cross between a wolf and a big cat--nor could you produce a viable pup/kitten hybrid by crossing any species of wolf (the domestic dog is a subspecies of the gray wolf ''Canis lupus'') with any species of big cat.
:Evolutionary theory doesn't propose that one would be able to cross and dog and a cat. Cross-species mating is not a prediction of the Theory of Evolution. What the theory does propose is that through various selection processes a single species could split into two species which were incapable of breeding with each other, and this has been observed.
:Evolutionary theory doesn't propose that one would be able to cross and dog and a cat. Cross-species mating is not a prediction of the Theory of Evolution. What the theory does propose is that through various selection processes a single species could split into two species which were incapable of breeding with each other, and this has been observed. {{unsigned|SSchultz}}
:: TerryH's point was that speciation only occurs within boundaries. He already agreed that speciation occurs, but he says that it only occurs within limits. Your answer doesn't argue otherwise. Dogs have "evolved"—into other dogs. Cats have "evolved"—into other cats. Dogs have not evolved into something that is not a dog, and cats have not evolved into something that is not a cat. [[User:Philip J. Rayment|Philip J. Rayment]] 05:52, 27 December 2007 (EST)
"But didn't Miller and Urey show how amino acids probably formed in the early atmospheric conditions?" No, they didn't. First, they set up a gas mixture that might work, with no good reason to suppose that those were the gases that were ever the way earth's atmosphere was put together. Second, they got a racemic mix of amino acids--not the uniformly left-handed mix that we observe in all of life today.
"But didn't Miller and Urey show how amino acids probably formed in the early atmospheric conditions?" No, they didn't. First, they set up a gas mixture that might work, with no good reason to suppose that those were the gases that were ever the way earth's atmosphere was put together. Second, they got a racemic mix of amino acids--not the uniformly left-handed mix that we observe in all of life today.