origin of light-sensitivity (The atheist delusion)

by whitecraw, Friday, February 01, 2008, 10:23 (6139 days ago) @ dhw

'I stand by my first statement that natural selection does not explain physical change and does not explain the mechanism that enables such changes to take place. Natural selection is only part of the process of evolution and explains why changes are perpetuated.' - You're right. The natural selection bit of the theory of evolution by natural selection only explains how particular physical characteristics come to predominate in populations; it does not explain how variation in physical characteristics within a population occurs. It's the biochemistry bit of the theory that does this. The physical changes that lead to variation within a population occur as a result of changes in a DNA sequence, usually occurring because of errors in replication or repair. According to the theory, random mutation at the genetic level is the ultimate source of the physical changes that give rise to variations in physical characteristics within a population, which either survive in or die out in a population depending on whether or not they are disadvantageous to the bearers of those characteristics in the competition to live and reproduce.