Incredible evolution

http://www.sciencedaily.com/releases/2007/08/070809130025.htm

"Modification of histones has been studied for some time, now we are
moving to understand the modification of something that modifies
histones," Shen says of INO80.

Shen's research is conducted in yeast, but the pathways involved are
conserved in all forms of life with complex cellular organization,
known as eukaryotes, right on up to humans, Shen notes."

It seems to me that repair mechanisms are essential for life. Are
there any examples of organisms that lack these complex systems?

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