“The symbionts living in my bloodstream can turn carbon dioxide back into oxygen, indefinitely. They get some energy through my skin, from sunlight, and they release any glucose they can spare – but that’s not nearly enough for me to live on, and they need an alternative energy source when they’re in darkness. That’s where the symbionts in my stomach and intestines come in; I have thirty-seven different types, and between them, they can handle anything. I can eat grass. I can eat paper. I could live off old tires, if I had a way of cutting them into pieces small enough to swallow. If all plant and animal life vanished from the face of the Earth tomorrow, I could survive off tires for a thousand years. I have a map showing all the tire dumps in the continental USA. The majority are scheduled for biological remediation, but I have court actions in progress to see that a number of them survive. Apart from my own personal reasons, I think they’re a part of our heritage which we owe to future generations to leave untouched.”

I went back and intercut some microscope footage of the tailored algae and bacteria inhabiting his blood and digestive tract, then a shot of the tire dump map, which he’d displayed for me on his notepad. I played with an animation I’d been preparing, a schematic of his personal carbon, oxygen, and energy cycles, but I wasn’t yet sure where it belonged.

I’d prompted him: “So you’re immune to famine and mass extinctions – but what about viruses? What about biological warfare, or some accidental plague?” I cut my words out; they were redundant, and I preferred to intrude as little as possible. The change of topic was a bit of a non sequitur as things stood, though, so I synthesized a shot of Landers saying, “As well as using symbionts,” computed to merge seamlessly with his actual words, “I’m gradually replacing those cell lines in my body which have the greatest potential for viral infection. Viruses are made of DNA or RNA; they share the same basic chemistry as every other organism on the planet. That’s why they can hijack human cells in order to reproduce. But DNA and RNA can be manufactured with totally novel chemistry – with non-standard base pairs to take the place of the normal ones. A new alphabet for the genetic code: instead of guanine with cytosine, adenine with thymine – instead of G with C, A with T – you can have X with Y, W with Z.”

I changed his words after “thymine” to: “ – you can use four alternative molecules which don’t occur in nature at all.” The sense was the same, and it made the point more clearly. But when I replayed the scene, it didn’t ring true, so I reverted to the original.