Because ATP [= adenine triphosphate] not only plays a fundamental role in biological energy exchange (the energy content of the last bonding is, under "remaining" of ADP [= adenine diphosphate], together with the phosphate residue, transferred to other molecules), but [at the same time] appearing as "universal" system-constituent of living matter anyway, one may grant it also a phylogenetically great age, even when it is about a regression such that ATP is the residue -- in this case one may of course also speak of a "split-off" -- of a headless ("nucleic acid") as well as bodyless ("protein") and only a tool group retaining once "living" specialist. (remotely comparable to the erythrocyte [red blood cell) ].