And ah mutation. That's what Evolution is supposed to be.. Mutation. Funny thing is, as organisms, there never can be new information added to our make-up. It's impossible. The information can be rearranged, or partially lost... but new information is never added. Why? Because it just doesn't, see it can't exist where it doesn't exist! This is why we didn't evolve from single cell organisms. The information in our genetic makeup has to be there. So yea mutation does occur, but again, it's simply the rearrangement of information, or the loss of.
It is a very easy word to use, "mutation." We learned it in school, and even more likely from a comic book, or the movie "X-Men." Kimball's online textbook of biology has
a brief, but excellent discussion of mutation. Anyone who would rather get their facts straight from there are encouraged to do so.
MoreJesus has made the standard creationist claims, and is wrong again. Because argument is so common however, it is worth examining more closely. First, evolution is not merely "mutation." The notion that "mutation" is the be all and end all of evolutionary theory is to ignore, or be ignorant of the basics of the theory. Evolution in a simplified form is "populations decent with modification subjected to natural selection resulting in reproductive isolation" When Darwin proposed his ideas nearly 150 years ago, he had no idea of how "decent with modification" actually operated and the ideas he had were wrong. But, simple observation can show anyone that "descent with modification" is the true nature of the world. Consider your own family; you look a bit like your parents, but not exactly like them. Under most circumstances you share just under 50% of your genes with each parent. You also look more like your siblings than say your cousins and more like your cousins than an unrelated person. But, other than identical twins, nobody shares the identical genes with any other person.
We know today that the mature organism is the result of the interaction of genes and the environment. This is much more complicated than Darwin's idea because the environment (including the history of the individual organism) does in fact directly alter the phenome. So when we view the genome it must be as a set of
possibilities which might or might not be ever expressed. We also know that "natural selection" is more complex than thought by Darwin. For example, while the environment shapes an organism, an organism (or population of organisms) is altering the environment. Further, it is recognized today that "natural selection" is a phenomena that effects entire populations acting across generations and is not merely variation in individuals.
The ideas above are expanded and shown with examples in
29+ Evidences for Macroevolution The Scientific Case for Common Descent" by my colleague Dr. Douglas Theobald.
At the beginning of the 19th century the experiments of Gregor Mendel were rediscovered and the science of genetics was born. It was discovered that different kinds of organisms had different numbers and shapes of
chromosomes (lit. color+body) and that radiation and/or chemicals could alter them. Subsequent development of an organism with an altered chromosome varied from the normal wild type. These early experiments were rather like making an omelet with only a hammer and a blowtorch and lead to the false notion still promoted by creationists today that "all mutations are harmful." Much of the medical literature on mutations is of course focused on those implicated in disease, just as most well studied bacteria are those that cause diseases. You will have noticed this in Kimball's discussion of mutation. Even today, some scientists inappropriately use the word "mutation" to refer to a noxious change in DNA, and "polymorphism" for the mutations that are silent, or beneficial.
So, what are some common sorts of mutations? The most common, and generally least significant in isolation, is the point mutation or single base substitution. These are typically "silent," that is they do not directly alter the function of the gene, or its product (if any). They can very subtly effect evolutionary change by making later mutations more likely, or by making later mutations more likely to alter gene or gene product function.
But for the purpose of examining MoreJesus's claim about mutation and
information, single point mutations are an excellent test case. The link is to Prof. David J.C. MacKay's web page on Information Theory at the world famous Cavendish Laboratory, Cambridge University. I will try to present a very simplified version of information as it applies to genetics. For one of the more important books on this topic, read "Information Theory and Molecular Biology" by Hubert P. Yockey, or his "Information Theory, Evolution, and the Origin of Life."
So,
what is information? A key discovery by Claude Shannon was that information could be measured in transmission. That is, any bianary string could be transmitted over any channel and the recieved string could be compared to the original. The change between the two roughly measures the information content of the system.
This has some interesting implications, and is typically misrepresented by creationists.
Lets consider a
sequence of letters that represent the nucleic acids;
5' ...AUGGCCUGGACUUCA...3'
which will make the following peptide when
subject to Gene Translation: RNA -> Protein
Met-ALA-TrP-ThR-Ser-
If a SP mutation happens to a gamete cell so that the sequence becomes;
5' ...AUGGCUUGGACUUCA...3'
there will be no change in the expressed peptide (see
Genes and Gene Expression) because GCC and GCU transcribe the same amino acid, Alanine.
However, the information content of the genetic system has been increased. In more significant mutations,
such as gene doubling, the new sequence,
5' ...AUGGCCUGGACUUCA...3'...5' ...AUGGCCUGGACUUCA...3' is obviously an information increase.
A fairly accesable article showing how such mutations not only add genetic information to populations, but inevitably lead to complex systems is "Evolution of biological complexity" Christoph Adami, Charles Ofria, and Travis C. Collier, PNAS | April 25, 2000 | vol. 97 | no. 9 | 4463-4468.
