Nevertheless he persevered. And over the course of a few weeks’ absorbed reading, he certainly gave himself a better orientation in the field than he had ever had before. Previously his impression had been that the longevity treatment consisted of a fairly straightforward injection of the subject’s own DNA, the artificially produced strands reinforcing the ones already in the cells, so that the breaks and errors that crept in over time were repaired, and the strands generally strengthened. This much was true; but the longevity treatment was more than this, just as senescence itself was more than cell-division error. It was, as one might have predicted, much more complicated than just breaking chromosomes; it was an entire complex of processes. And while some were well understood, others were not. Senescencial action (aging) took place on every level: molecule, cell, organ, organism. Some senescence resulted from hormonal effects that were positive for the young organism in its reproductive phase, and only later negative for the post-reproductive animal, when in evolutionary terms it no longer mattered. Some cell lines were virtually immortal; bone-marrow cells and the mucus in the gut went on replicating for as long as their surroundings were alive, with no sign at all of time-related changes. Other cells, such as the nonreplaced proteins in the lens of the eye, underwent change that was driven by exposure to heat or light, regular enough to function as a kind of biological chronometer. Each kind of cell line aged at a different speed, or did not age at all; thus it was not just “a matter of time” in the sense of a kind of Newtonian absolute time, working entropically on an organism; there was no such time. Rather it was a great many trains of specific physical and chemical events, moving at different speeds, and with varying effects. There was a fantastically large number of cell-repair mechanisms inherent in any large organism, and an immune system of great and various power; the longevity treatments often supplemented these processes, or worked on them directly, or replaced them. The treatment now included supplements of the enzyme photolyase, to correct DNA damage, and supplements of the pineal hormone melatonin, and dehydroepiandrosterone, a steroid hormone produced by the adrenal glands. . . . There were about two hundred components like these in the longevity treatment now.