Lorem Ipsum to Hebrew (redux)
The previous post: Lorem Ipsum to Hebrew gets a little side tracked in the technical details. There's a program to evolve text using mutation-selection cycles and a program to chart the results, but it mostly misses the point.
Questions for Evolutionists asks:
How can mutations (recombining of the genetic code) create any new, improved varieties? (Recombining English letters will never produce Chinese books.)
This question has two problems. First, it presents a straw man: nobody contends that mutations alone result in the awe inspiring adaptations possessed by the life all around us. The vast majority of mutations are silent-site mutations and have no effect on the phenotype of the resulting creature, because the mutation occurs in a non-coding section and is never expressed. The majority of the rest of mutations are deleterious and give you cancer or Down's syndrome or something equally nasty. Only a tiny fraction of mutations have any beneficial effect on those carrying the mutation.
Mutation alone would never have produced the staggering variety of life that populates the Earth. Mutation combined with selection on the other hand can produce staggering effect on a population. Mutation introduces novel varieties into a population with each generation. While some mutants will be more fit than than their parents most will not be and some will be decidedly less so. The most fit individuals will found the next generation and beneficial mutations will slowly accumulate generation after generation producing the adaptations observed in current populations.
Second, conceptualizing mutation as moving letters around, is a complete underrepresentation of the ways in which our genome's can be mis-copied. There can be deletions, replacements, duplications of single bases or entire sections of DNA. Additionally, it is at the completely wrong level of granularity. Mutation would not occur on the letters themselves but on the bytes representing them. With only 256 bytes to choose from you can represent either Macbeth or the I Ching with ease. Likewise, using only C, G, A and T you can just as easily spell E. Coli and H. Sapiens and you can almost spell Human immunodeficiency virus, but you would be missing the U.
Conclusion
So how can mutation create new and improved variants? When acting alone, mutation would only ever improve an individual through luck. It is after all a random process and would mostly only introduce deleterious changes. When combined with selection on the other hand, together mutation and selection can produce amazing adaptations by allowing beneficial mutations to accumulate over generations.