The Goliath Stone by Larry Niven, Matthew Joseph Harrington

loves mankind but is sick of being cheated on. —Anyway, what I was getting at is, you can wave your hands all day, but to predict results in a complex system, you need something more complex than the system you’re trying to predict.”
    “Like the Human Genome Project stalling out as soon as the mapping was done.”
    “Exactly. Everything interacted and nobody could figure out what did what when.”
    “Except Connors,” she said.
    Toby opened his mouth, but nothing came out.
    “You hadn’t realized,” she said.
    He shook his head.
    “I did almost as soon as you mentioned his idea. The nanos can’t just fix DNA within a cell, they have to compare each cell to the next to make sure the best copy of a given chromosome is what’s used. The frayed parts on the ends have to be rebuilt, so that comes from sex cells. Otherwise you have nice clean chromosomes, but they’re all old. That means the nanos are also comparing all the mutations that cropped up in your life with what you started with. The nanos are also implementing the changes.”
    “That means there’s more than one or two nanos per cell,” he said.
    “I realized that when my skin went red,” she said. “They’re smaller than a virus. There must be dozens per cell.” She looked alarmed. “Why are you looking like that?”
    He didn’t know what he looked like, but he said, “There can be thousands of mitochondria per eukaryotic cell. I’d been assuming one or two nanos were hooked up to each cell, and that’s probably what it is for most people. But if the program that was loaded into ours used our intestinal bacteria for raw materials—we’re talking pounds .”
    “Ugh.”
    “Oh. Sorry, wearing my doctor hat.”
    “It’s okay, go on.”
    “The thing is, we could easily have a nano attached to every mitochondrion in our bodies. —My God, of course we do. The man had fibromyalgia, the first thing he’d have designed them to do is clean calcium phosphate out of mitochondria! —If they’re all in a network, it can definitely do a simulation of what shape the protein made by a mutated gene will be, and how it’ll interact with … everything.”
    “Toby, even with limited connections, could something that big take over?”
    “I don’t think it would. It’d be too busy. The cluster for a given cell is almost certainly supervising the operation of the cell. The network’s responding to what we want our bodies to do, but it’s not interfering with our brains, or we wouldn’t be discussing it.”
    “So how do we find out if the network’s that big?”
    He tilted his head and half-smiled. “The color change is a big hint, but I can think of a way to confirm it.” Before he could lose the nerve, he picked up the knife he’d used to divide the dough into baguettes and slashed it across his left palm.
    “ Toby! ”
    “I thought it would close up,” he said, staring at his hand.
    “Where’s your bag?”
    “Don’t need it,” he said, and showed her the thin scratch across his palm.
    “Uh,” she said.
    “It didn’t let the knife through,” he said. “Filaments. Connors must have deliberately overridden that to let them draw blood today. I doubt anything short of artillery shrapnel could get in otherwise.”
    After they were both silent for a long moment, May said in a very small voice, “Toby?”
    “Yes?”
    “Did he wear glasses?”
    They kept setting each other off for quite a while, their laughter tinged with hysteria. It might have stopped earlier if he’d had the presence of mind not to say “Yes” the first time they both calmed down.
    *   *   *
    He finally got the bread into the oven, then got out the phone again and called. He got voice mail. “Mycroft, we need to discuss the issue of speciation,” he said, and signed off.
    May was wide-eyed when he looked at her. “You’re afraid we’re not human.”
    “Yes, I am.”
    “Toby, I think that’s not the question anymore. I think in a thousand