Prof Campbell: This is the key question about how a new species appears. The molecular definition of a species is that its DNA cannot mix with another species to form an individual that is fertile. For one species to separate into two then there has to be a gradual separation of groups of individuals. An example of this would be the finches on the different Galapagos islands, enabling then to evolve separately. I have produced an hypothesis to explain the Rubicon that is crossed when a particular sperm fails to fertilise an egg. The basic idea is that the rates of reactions from the egg and sperm don't match, so the fertilised egg dies.
Question 22
How is it that the human brain has evolved to a level far in excess of that required for mere survival?
Prof Campbell: Very interesting question, but isn't this rather subjective? What do you mean by saying that we have evolved a brain far in excess of what is needed for mere survival. Darwin and Wallace tell us that indeed there was a selective advantage of our intellect and creativity all the way from pre-chimpanzee to today.
Question 23
Dawkins frequently mentions 'random mutations'. How does he/science know with surety they are random and not part of a pattern he/science is unable to discern?
Prof Campbell: 'Random' simply means unpredictable. But in genetic engineering we use both random and directed mutations to produce altered proteins and organism characteristics.
Question 24
It is clear that Darwin's Origin of Species describes the origin of biological complexity and variation. Even though the science is far more difficult to approach for the layman it also seems clear that the Universe and everything in it evolved from a Big Bang. If there is a scientific 'missing link' it seems to be the point at which organic chemistry began - and the evolution of that chemistry. The heavy elements (the by-products of stars) - having been thrown together and formed some minerals and other compounds - what mechanism takes us from there to amino acids, proteins, nucleotides and from nucleotides to nucleic acid and RNA? The answers I can find all seem to revolve around a primordial soup. Is this the only area of scientific inquiry on life origins?
Prof Campbell: The elements evolved in stars by nuclear fusion. Helium formed from two hydrogens and so on. This was one of Fred Hoyle's major contribution to science. Urey's famous experiment using electric discharge across a 'laboratory' primeval soup generated biological molecules such as amino acids. A key issue is how the handedness of biological molecules occurred, i.e. right handed sugars and left handed amino acids.
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