The Russian biologist and historian
Zhores A. Medvedev, reviewing Weismann's theory a century later, considered that the accuracy of
genome replicative and other synthetic systems alone could not explain the "immortal"
germ cell lineages proposed by Weismann. Rather Medvedev thought that known features of the biochemistry and genetics of
sexual reproduction indicated 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 cells are created by
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
chromosomes from the types of damage that caused irreversible ageing in
somatic cells. ==Basal animals==