I guess the whole issue here is whether or not mutations on the cellular and molecular level are sufficient enough to prove evolution. Scientifically
speaking, yes, small mutations are enough to prove evolution and natural selection on this scale. Take for instance one aspect of Evolutionary
Biology, called Viral Evolution, which has created numerous problems for vaccine researchers over the years. In particular, Viruses that have a
nucleic acid that is primarily RNA based lack the DNA Polymerase enzyme for viral replication and repair of DNA. This essentially means that when
they enter the host cell for replication they require the DNA Polymerase to replicate and reform their original RNA structure. Fundamentally, because
they require cellular DNA for this function they are, in principal, mutating each and every time they enter and exit a cell. Ergo in contrast, DNA
based viruses have much longer mutation rates, as the polymerase is able to fix unstable DNA. What we see here is that most viruses are able to
mutate and replicate successfully enough to adapt to whatever environmentally constrained conditions they are put in. This means that not only are
they able to adapt and change to the environment, but are able to co-evolve along with the host. One very good indication that evolution happens all
the time on the micro level is when we look at specific types of viruses and their interactions with human tissue. RNA based viruses like HIV
overcome Immunological memory by mutating into slightly different variations of the same virus though change on their surface proteins each time they
replicate. This process is done so efficiently and so often that the virus is literally able to evolve faster than the host organism itself...ie.
there is the proof for the Theory of Evolution.
Interestingly enough we actually see proof of evolution at the cellular and molecular level easier than at the Macro level. Take for another example
the Human Papilloma Virus (HPV) and the Herpes Virus, which have effectively been traced back to primates. By comparing retroviral derived sequences
in human and primate genomes we have seen that some viruses have evolved to suit their preference for certain types of tissue. This means that viral
preference for tissue was established before humans split off from primates, and would also indicate a distinct relationship between the two species
as these viruses only prefer interrelated tissue.
Bacterium are also small organisms that go through change and evolve to suit their environment. Two of the first forms of life on earth, Bacteria and
Archaea have further subsets which divided into Eukaryotic and Prokaryotic cells. The Eukaryotic cells are of particular importance, because
according to current evidence they actually evolved to the point where they were able to assimilate independant Prokaryotic cells into their organelle
structure in the form of Mitochondria. Through the result of common endosymbiosis they have worked together as evolutionary partners at the cellular
level. Evolution actually shows that the two were actually seperate organisms at one time with the Mitochondria being a prokaryotic proteobacterium.
This can be supported because Mitochondrian DNA is completely seperate and different than the DNA found in the Nucleus, they have two membranes, and
the ribosomes found in Mitochondria resemble those found in bacteria. Again, here we have two seperate organisms, supported by the fossil record,
that have co-existed and evolved with each other to help fulfill common objectives.
Obviously, I use Viruses and Bacteria to describe how evolution can take place in an species without noticeable changes on the Human scale, and
haven't yet started talking about noticeable human evolution. However, since these micro changes are what change the macro environment eventually it
should be duely noted that Evolutionary changes in the viral, bacterial, or cellular level are enough to change a species over a given amount of
Now, with some of this information we can look at what the definition of a mutation is:
Mutation: Medical Definition
A permanent change, a structural alteration, in the DNA or RNA...Mutations are the necessary raw material of evolution.
Now, a look at the definition of evolution:
Evolution: Medical Definition
A developmental process in which an organ or organism becomes more and more complex by differentiation of its parts; a continuous and progressive
We can see that a common theme within the definitions of Evolution and Mutation is CHANGE. Mutations, which are described as a permanment change in
DNA or RNA by the above definition, are necessary for evolution which can be characterized by the change in an organism. Studies conducted with
Viruses and Bacteria as described previously have effectively proven that evolution and natural adaptation does occur. Whether it be Macro or Micro
does not matter in this case, because if evolution can happen on either level then it can change the other.
[edit on 4-9-2007 by Jazzerman]