INEXORABLE ENTROPY. “The crucial suggestion is that the events that occur after reproductive success that fail to maintain the system and increase the likelihood of dying are called age changes. That is, there is an increase in molecular disorder for which repair processes increasingly fail to correct. The second law of thermodynamics applies, that is, entropy increases.”
http://protein.bio.msu.ru/biokhimiya/contents/v62/full/62111380.html