“I don’t worry aloud about the oxygen supply, either—”
“Obviously.”
“—or the other necessities of survival. It would annoy me less that we’re heading into a new puritanical era if the puri-tanism concerned itself about things that matter.” Hanno struck match to tobacco and drew the fire alight.
“Well, I worry about you. Okay, your body has recovered from traumas that would have finished off any of us ordinaries, but that doesn’t mean your immortality is absolute. A bullet or a swig of cyanide would kill you as easily as me. I’m not at all convinced your cells can stand that kind of chemical insult forever.”
“Pipe smokers don’t inhale, and for me cigarettes are faute de mieux.” Hanno’s brows knotted slightly. “Just the same … do you have any solid scientific reason for what you said?”
“No,” Giannotti admitted. “Not yet.”
“What are you turning up lately, if anything?”
Giannotti sipped from his glass. “We’ve learned of some very interesting work in Britain. Fairweather at Oxford. It looks as though the rate at which cellular DNA loses methyl groups is correlated with lifespan, at least in the animals that have been studied. Jaime Escobar here is setting up to pursue this line of inquiry further. I myself will re-examine cells of yours from the same viewpoint, with special reference to glycosylation of proteins. On the QT, of course. I’d like fresh material from the four of you, blood, skin, biopsy sample of muscle tissue, to start new cultures for the purpose.”
“Any time you want, Sam. But what does this signify, exactly?”
“You mean ‘What might it signify, at a guess?’ We know little thus far. Well, I’ll try to sketch it out for you, but I’ll have to repeat stuff I’ve told you before.”
“That’s all right. I am a simon-pure layman. My basic thought habits were formed early in the Iron Age. Where it comes to science, I can use plenty of repetition.”
Giannotti leaned forward, caught up in his quest. “The British themselves aren’t sure. Maybe the demethylation is due to cumulative damage to the DNA itself, maybe the methylase enzyme becomes less active in the course of time, maybe something else. In any event, it may—at the present stage this is only a suggestion, you understand—it may result in deterioration of mechanisms that hitherto kept certain other genes from expressing themselves. Maybe those genes become free to produce proteins that have poisoning effects on still other cellular processes.”
“The checks and balances begin to break down,” Hanno said mutedly, through a cloud of blue smoke.
“Probably true, but that’s so vague and general a statement, practically a tautology, as to be useless.” Giannotti sighed. “Now don’t imagine that we have more than a single piece of the jigsaw puzzle here, if we have that much. And it’s a puzzle in three dimensions, or four, or n, with the space not necessarily Euclidean. For instance, your regeneration of parts as complex as teeth implies more than freedom from senescence. It indicates retention of juvenile, even fetal characteristics, not in the gross anatomy but probably on the molecular level. And that fantastic immune system of yours must tie in somehow, too.”
“Yeah.” Hanno nodded. “Aging isn’t a single, simple thing. It’s a whole clutch of different … diseases, all with pretty much the same symptoms, like flu or cancer.”
“Not quite, I think,” Giannotti replied. They had been over the same ground more than once, but the Phoenician was right about his need for that. He must have won to a terrifying degree of knowledge about himself, Giannotti sometimes thought. “There does appear to be a common factor in the case of every mortal organism with more than a single cell—and maybe the unicellulars too, maybe even the prokaryotes and viruses—if only we can find what it is. Conceivably this demethylatibn phenomenon gives us a clue to it. Anyhow, that’s my opinion. I concede my grounds are more or less philosophical. Something as biologically fundamental as death ought to be in the very fabric of evolution, virtually from the beginning.”
“Uh-huh. Advantage to the species, or, I should say, the line of descent. Get the older generations out of the way, make room for genetic turnover, allow more efficient types to develop. Without death, we’d still be bits of jelly in the sea.”