[Dr43%er]

"You need to ask how you get that which is non living to give rise to that which is living"

I wont complicate things by asking you to define 'living'. However a belief in the Theory Of Evolution can be held independently of an understanding of the origins of life. There are ideas proposed that life may have arisen from self-replicating molecules like RNA but as I've stated this is nothing to do with evolution.


"Also if the way a species is meant to change from one to another is by genetic mutation, how come we have never documented a good mutation? The only mutations we see in nature are bad ones, which nature will select against."


You seem to be lacking understanding in the basic concept of mutation.

"Beneficial mutations are commonly observed. They are common enough to be problems in the cases of antibiotic resistance in disease-causing organisms and pesticide resistance in agricultural pests (e.g., Newcomb et al. 1997; these are not merely selection of pre-existing variation.) They can be repeatedly observed in laboratory populations (Wichman et al. 1999). Other examples include the following:

* Mutations have given bacteria the ability to degrade nylon (Prijambada et al. 1995).
* Plant breeders have used mutation breeding to induce mutations and select the beneficial ones (FAO/IAEA 1977).
* Certain mutations in humans confer resistance to AIDS (Dean et al. 1996; Sullivan et al. 2001) or to heart disease (Long 1994; Weisgraber et al. 1983).
* A mutation in humans makes bones strong (Boyden et al. 2002).
* Transposons are common, especially in plants, and help to provide beneficial diversity (Moffat 2000).
* In vitro mutation and selection can be used to evolve substantially improved function of RNA molecules, such as a ribozyme (Wright and Joyce 1997)."


Dean, M. et al. 1996. Genetic restriction of HIV-1 infection and progression to AIDS by a deletion allele of the CKR5 structural gene. Science 273: 1856-1862.


Whether a mutation is beneficial or not depends on environment. A mutation that helps the organism in one circumstance could harm it in another. When the environment changes, variations that once were counteradaptive suddenly become favored. Since environments are constantly changing, variation helps populations survive, even if some of those variations do not do as well as others. When beneficial mutations occur in a changed environment, they generally sweep through the population rapidly (Elena et al. 1996)

Elena, S. F., V. S. Cooper and R. E. Lenski. 1996. Punctuated evolution caused by selection of rare beneficial mutations. Science 272: 1802-1804.



"What about the lack of transitional forms in the fossil record?"

Darwin himself had reasonable doubts about the consistency of his theory when faced by this problem. However since then many examples of transitional fossils have been discovered; such as those as believed to be the ancestors of the modern Horse, discovered by Othniel Charles Marsh. There will always be gaps in the fossil record, but to suppose that this means that all other evidence for transitional forms is null and void is foolish.


All the best,
Duncan

Doctor's Practice Manager