Immortality

====Immortality of the germline====

Individual organisms ordinarily age and die, while the germlines which connect successive generations are potentially immortal. The basis for this difference is a fundamental problem in biology.   The Russian biologist and historian [[Zhores A. Medvedev]]<ref name="Medvedev1981">{{cite journal |last=Medvedev |first=Zhores A. |title=On the immortality of the germ line: Genetic and biochemical mechanisms. A review |journal=Mechanisms of Ageing and Development |volume=17 |issue=4 |year=1981 |pages=331–359 |issn=0047-6374 |doi=10.1016/0047-6374(81)90052-X|pmid=6173551 |s2cid=35719466 }}</ref> considered that the accuracy of [[genome]] replicative and other synthetic systems alone cannot explain the immortality of [[germline]]s. Rather Medvedev thought that known features of the biochemistry and genetics of [[sexual reproduction]] indicate the presence of unique information maintenance and restoration processes at the different stages of [[gametogenesis]]. In particular, Medvedev considered that the most important opportunities for information maintenance of [[germ cell]]s are created by [[genetic recombination|recombination during meiosis]] and [[DNA repair]]; he saw these as processes within the germ cells that were capable of restoring the integrity of [[DNA]] and [[chromosome]]s from the types of damage that cause irreversible aging in [[somatic cell]]s.