Prof Campbell: Natural selection is not a conscious process. It occurs through small change by small change leading to a selection of DNA that is 'fittest' for a particular environment, and thus having a higher chance of being passed on to the next generation. So in plants, natural selection works the same way.
Question 18
I have no problem in accepting Darwinism. What I do not understand is how did living organisms begin in the first place and what was there before life began?
Prof Campbell: Life began on Earth around 3800 million years ago. The big bang, or mini bangs to Hoyle, occurred 15,000 million years ago. Some, like Hoyle and Wickramasinghe, believe that life is cosmic, and came to Earth via microbes formed elsewhere in the Universe. This is panspermia. Others believe that a primeval soup formed once the Earth was cool enough. The atmosphere was quite different from today. There was no oxygen. Rather, lots of formaldehyde and ammonia, that, with electrical and chemical activity, lead to the synthesis of the first biological molecules. These then grouped together to form the first cell. This took 100's of millions of years.
Question 19
Given that natural selection works on humans and that physically attractive people presumably have a reproductive advantage why are so many of us still... less than beautiful? Shouldn't the genes for buck teeth, big ears and crooked noses have been weeded out in our pre-historic past?
Prof Campbell: 'Attractiveness' is a classic example of variation within a population. What is physically attractive to one person is not to another. Some look to physical attributes such as muscles, other to sexual form, and others still to intellectual and creative activity, including that in the lovemaking process. Who says 'big' ears are unattractive to everyone. People with buck teeth can have a very attractive smile and can be very intelligent.
Question 20
How does evolution manage to 'create' the sex characteristics for a new species? How we can evolve from an asexual animal?
Prof Campbell: The evolutionary origin of 'sex' is an interesting question. It is very ancient. Sex is simply a mixing of DNA! Even bacteria have sex. They have so-called plasmids that pass DNA between individuals that can be incorporated into the main genome. But sex as we know it requires two sets of chromosomes. Bacteria only have one chromosome per cell. We have two, one from each parent.
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