Rority lounged back in his recliner, sipping his gargleblaster and puffing his stratodoober as the sun shone on his pale gray skin. Life was good.
He'd recently returned from a trip from prehistoric times, back even before firearms had been invented, let alone the discovery of atomic power. It was a good trip, because the ancient protohumans had documented his visit. Of course, the protohumans had couched it in religious terms; it was kind of strange for he, Rority, to be seen as an angel. He grinned at the thought of a drunken, stoned angel. But because it had been documented, he had to go back to make sure it had happened, or it wouldn't have. If that had happened, the timeline might have been distorted and the protohumans might have exterminated themselves, as the mathematicians had so carefully pointed out with numbers.
He was still trying to make a drink he'd discovered on the trip that the ancient protohumans called "beer". He'd tried it and found that the gargleblasters were weak, pale shadows of what the ancients had had.
"Hey, Rority, how's that 'beer' stuff coming?" Rority looked up -- it was his partner, Gumal.
"Well, from the instructions it'll take another couple of days. I hope I got the formula right."
"Don't you mean 'recipe'?" Gumal twittered as another chair assembled itself from seemingly nothingness, the nanobots arranging themselves to the reclining chair shape. "They didn't have science ten million years ago, you know." He sat down.
"Smartass. You know the difference between a chemist and a cook?"
"The same difference between a physicist and a chemist!"
"That's the dumbest joke I ever heard," Gumal snorted.
"What do you expect?" Rority said. "It's a ten million year old joke."
"The joke's on you, pal," said Gumal. "They've got another trip planned for us."
"Shit. When to now? Is it a dangerous mission?"
"The worst. It isn't anthropology or biology, we have to make sure the timeline stays intact."
Rority sighed. "Damn. You don't want to tell me, so it must be pretty bad."
"It is. We're going to have to die, and be dissected."
"God Damn it! I hate resurrection! It takes forever to get my memory right, and the dying itself is even worse. Shit!"
"Rority, you know good and well if we don't take this mission you'll never have existed, and neither will I have. The arithmetic boys say that if we don't go, the protohumans will have had some sort of catastrophe that destroyed them -- and we're descended from them. And look at the brighter side -- you don't have to have sex with a neanderthal."
"You're an asshole, asshole. I didn't fuck her, and she wasn't a neanderthal. She was a protohuman and it was artificial insemination, you dickweed."
Of course, being from ten million years in the future and we being only protohumans who could understand our descendants even less than stone age men would be able to understand us, this is about as close as we can come to conveying what was actually said as our limited intelligence can comprehend. Needless to say, the neohumans could understand us perfectly well, and we could probably understand them about as well as a chimpanzee could understand us. But it's a rough approximation, nevertheless.
Gumal laughed. "Lighten up, dude! Where's your sense of humor? The funniest part was you having to go back and undo it, because it turned out that she had a parthenogenesis." He laughed even harder.
"Ok, asshole. Let me read up on it." He held his hand out, and a book appeared in it, seemingly, again, out of thin air, assembling itself out of the microscopic networked robots. Almost everything but food and drink was made out of nobots. A protohuman would have thought it magic, rather than technology. Rority read the book -- which was, of course, nothing like the books we protohumans have. Neither paper nor an electronic device, it appeared to be a single, thin cardboard which changed its text and illustrations with the movement of the user's eyes.
"Wow, these protohumans are... did they really think we come from Mars?"
"Well, you have to remember," Gumal pointed out, "that they'd not been to Mars or any other planet, not even the moon, not even their crude robots (if you could call their robots "robots"). They hadn't even been outside the Earth's atmosphere."
"Yes but... they knew about how diverse life is on Earth, but they expected extraterrestrials to look as much like them as they look like simians? It's just absurd! Even after they got their primitive machines to Mars, they had fiction with space aliens looking more like themselves than we do. I can't comprehend how they couldn't understand that if you can go faster than light, you can travel through time as well."
"Well, come on, they're only animals. Protohumans, not true humans. They were barely sentient."
"I guess. Well, lets get going. And hey, look on the bright side -- they have BEER. And it's even better beer than the beer you drank five thousand years earlier!"