posted on Sep, 1 2005 @ 01:19 PM
We are a chemical composition. Of course, there are aspects of the human body and some of its functions that we just haven't got to yet, so some is
still unkown.
If we were to live forever, then we would be violating the laws of physics, particularly the concept of entropy, the tendency for a system to go to a
more disorganized state. Fill a jar with a layer of blue marbles and another layer of white marbles. Shake the jar. See how many times you have to
shake it before the marbles form two distinct layers of blue and white. Thermodynamic principles in chemistry rely on entropic measurements.
You have to remember that biological systems are based off the work of enzymes. Each enzyme carries out one function, and with a very high success
rate as well. Once in a while, a mistake is made, and the enzyme does something wrong. This can lead to physiological problems.
A big reason as to why people think we die is due to Okazaki Fragment formation during DNA Replication. DNA can only be replicated in one direction.
While it is being "unzipped" so that it can be copied, one strand of it is uninterruptedly copied in the same direction of the unzipping. However,
since the opposite strand is antiparallel to the first strand, it is facing the opposite direction. Instead of waiting for the whole thing to get
unzipped so that it can start copying it from the start, your body copies small fractions of it at a time. These are called Okazaki Fragments, and
they are later all connected.
The clincher is that sometimes the very end Okazaki Fragment does not get connected and is lost. That cell's DNA is now permanently shorter. It is
hypothesized that this occurs more and more throughout one's life, which leads to functional coding loss in DNA, and you basically just don't have
the information of how to keep yourself alive.
Also remember that other factors contribute to DNA damage. High-energy ultraviolet light excites electrons in DNA and causes nucleotides to pop out of
the chain. Most of the time, your body fixes this. Once in a while, the wrong nucleotide is inserted. Once in an EXTREME while, both conjugate pairs
of nucleotides are knocked out of sequence, and the DNA molecule simply scoots back together. This is particularly devastating to the molecule, in
that it is read in 3-nucleotide sequences, and now the rest of the molecule is now offset and useless. This leads to cancers and other
abnormalities.
Anyway, the answer to your question is that we die because no chemical system is 100% accurate. There is a degree of imperfection to a chemical
system, otherwise we would be violating the laws of physics. Biochemical systems, such as humans, can be disrupted by surprisingly small details.