I was wondering, if aging is caused by oxidation because of our oxygen metabolism why do those microorganisms who don't breeath oxygen age and die?

Hi Adrian,

The process of aging is very complex, and involves more than just effects of oxidation. Both genetic and environmental factors contribute to aging.

Aging can be considered as a progressive failure of homeostasis (a term that means maintenance of a stable, constant condition), involving genes for maintenance and repair, random/unpredictable events leading to molecular damage and chance events determining the probability of death. Oxidation is one of many processes that may lead to these conditions (especially with respect to damaging structural proteins and DNA).

For more detailed review of various theories of aging you might like to read the following link:
http://www.benbest.com/lifeext/aging.html

Cheers,

David