Monday, 7 January 2008

I think evolution has goal

Yes you are wrong I am afraid. Evolution is the process of change through time of species by inherited changes. Heritable differences mainly come about from random mutation in the genome. These genetic differences between individuals lead to fitness differences between individuals, ie one individual is better able to produce offspring, thus spreading more of its genes in to the following generation, than another individual. For example, environmental change causes selection for a dark body morph in moths, stabding genetic variation and new mutations affecting body colour is then more favored by selection, and those with the dark body genes survive and reproduce better.



There is no end or goal to evolution. It is often mistakenly said that humans have stopped evolving. This is wrong and to suggest we have is to suggest that evolution is directed and has an ultimate goal. As long as genetic fitness variation exists there will always be some level of evolution because there is a difference between individuals in selection coefficient. Selection is also very unstable, it can change drastically an rapidly, evolution could only then stop if selection was constant and favored one "ultimate genotype" over all others in which case all genetic variation would cease to exist.



If we found another planet which had the exact same conditions and time as earth we may find the same species, but it is not likely. It requires the same mutations and selection processes occurring. Analogous to this is the observation of "many solutions to one problem" where different species use different adaptations to deal with a common problem. For example, geting oxygen is difficult for water deelling species. Sea mammals like whales gather oxygen by going to the surface and breathing and then holding their breath. Fish have evolved gills, a different solution to the same problem, to harvest oxygen from the water. These solutions evolve from random changes with selection acting only on the results (those that could filter oxygen from the water or hold their breath the best survived and reproduce best).

No comments:

Post a Comment