For - For (almost?) every scientific fact that we know,...

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For (almost?) every scientific fact that we know, there used to be a different theory that seemed to explain the same phenomena Before Mendel 's laws were discovered (and much later accepted) genetic inheritance was considered to be comparable to the mixing of liquids. Many people literally believed that this substance was actually blood; for others blood was a metaphor for liquid-like mixing, with no limit on the degree of dilution. Unlimited dilution was the key assumption, not which specific liquid was mixed. As an illustration of how widely this was believed, please consider one of the most intelligent criticisms made against Darwin's theory of evolution (which, please notice, was itself a replacement of earlier theories of evolution!). I refer to the criticism by a famous engineer whose name looks as it if it were not spelled correctly: Fleeming Jenkin (Yes! It really was spelled that way.). He was one of the engineers most responsible for early undersea cables. His objection to evolution by natural selection was that dilution would prevent continued evolution of any characteristic that deviated very much from the average. For example, extreme height might result in leaving many offspring, but if those offspring had offspring by individuals of average height, then the effect would be diluted and the advantage lost. This has often been called "The Swamping Argument". Unfortunately, the hypothetical example Jenkin used was not height, but skin color, and his discussion of the issue sounds (and was) racist. Nevertheless, his reasoning is regarded by experts as having been correct. In other words, were it not for the "lumpyness" and non-dilution of genes, which Mendel discovered, Darwin's mechanism of natural selection could not work. Neither Mendel nor Darwin realized this connection; if they had, then Mendel's research would have become famous in his own time. Darwin took Jenkin's objection very seriously, and thought perhaps it disproved natural selection as a workable mechanism for evolution. So did many other good scientists of the time.
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This note was uploaded on 11/05/2011 for the course BIOL 446 taught by Professor Staff during the Fall '10 term at UNC.

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For - For (almost?) every scientific fact that we know,...

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