“Well, that’s certainly a program for the future,” Bram said noncommittally.
Shira continued serenely, as if used to interruptions. “Until now, we’ve lacked the capacity to do molecular taxonomy in any meaningful way. Oh, we’ve been able to use cytochrome c sequencing to demonstrate that human beings are very far removed indeed from yeast—forty-five amino acid differences—not quite as far removed from cabbages, and closer still to heterochronic eggs. But now, of course, we have all those lovely tissue samples.”
“Horses,” Jorv said dreamily. “Zebras. Giraffes. Rhesus monkeys. Wolves. Original Man preserved them all.”
“And of course we’ve brought up scads of mouse bones from our deeper excavations. Man inadvertently carried mice and other vermin to the diskworld with him—just as, I suppose, he carried them with him everywhere he went. The mice didn’t manage to survive for long after humans departed the diskworld. They never adapted for airlessness, they weren’t able to burrow deep enough, and they quickly exhausted the more easily available sources of food. We found no mouse bones more recent than seventy million years old. But they still contained traces of cytochrome c.”
“And we had ourselves and Cuddlies available as a source of hemoglobin and serum albumin,” Jorv said. “Oh, there was no doubt at all!”
Shira brushed her hair back. “The longfoots were at several removes from us and Cuddlies—well beyond the limits of family or genus, let alone species. Farther still from Jorv’s giraffes, though we were able to do only DNA sequencing in that case. But the molecular differences between longfoots and mice—”
“Mus musculus,” Jorv interjected. “Same family as rats. If you remember your childhood Chin-pin-yin, it’s the same word. Big-mouse.”
Shira spared a tolerant glance for Jorv and finished what she had been saying. “…but the molecular differences between longfoots and mice were practically nil.”
Bram nodded at the longfoot skeleton. “That seems to settle it, then. Man did become extinct. And the next dominant species was that.”
Ame said, “We found something else.”
“What’s that?”
“We know how the Cuddlies got here.”
Bram picked his way down the tunnel, following Jorv’s bobbing yellow light. Loose gravel under his feet started slow-motion cascades as he proceeded, coming to rest long after he had passed. The lanky paleobiologist was right behind him, shedding enough light of her own for him to see by, and Ame brought up the rear. Bram, as an escorted guest, went unburdened; the other three wore many-pocketed tabards over their space suits and lugged an assortment of picks, hammers, and other small tools.
After what seemed like an endless trek, the tunnel opened out into a wide, low-ceiling space shored up by timbers. Other tunnels branched off the space, glimmers of light from a couple of them showing the presence of other work parties.
The thick timbers were ordinary vacuum-poplar. Seeing them brought a lump of homesickness to Bram’s throat till he remembered that vacuum-poplar had originated here, in the Milky Way, not in the Whirlpool galaxy.
Ame saw him looking. “The longfoots dug up a human lumberyard near here and took advantage of it. The wood must have been in vacuum and still good. Before that—” She indicated the branching tunnels where archaeological work was in progress. “—the longfoots used columns of native stone as well as steel griders that they brought with them. Evidently they didn’t have much of a structural plastics industry. It bears out your theory that they were a young civilization, newly come to star travel, Bram-tsu.”
“What was this place?”
“The longfoots had some of their own storehouses here. And living areas close by. We gleaned some insight into their social habits. There was some limited pair bonding in our sense, but mostly they lived in aggregates of fifty to a hundred members in which females were available to males on some kind of schedule of dominance. The living arrangements pointed to that, anyway. The females raised their young separately and cooperated in keeping males at bay for a period after parturition.”
“They don’t sound like a very pleasant people.”
“Rats don’t make very pleasant ancestors.”
Bram shuddered, remembering the fragment of film Ame had been able to show him. It had been part of an exhibit associated with the mounted rat skeleton and had shown a bedraggled brown animal with beady eyes and a naked tail greedily eating its way thorugh a store of corn, excreting as it went. Bram had been ashamed of his instant and automatic revulsion, telling himself that the rat was a life form like any other, with a right to existence. But Ame had told him that his reaction wasn’t unique—that rats seemed to raise the hackles of most humans.
“You’re being narrow-minded, Ame,” Jorv protested. “Seeing it from a human point of view. Different species, different biological imperatives. They might have been a perfectly decent folk. They acted cooperatively, after all.”
“Come here, I want to show you something,” Ame said.
She led Bram to a cache where specimens had been arranged with preliminary labels. There were bins of a dessicated, unfamiliar grain, shovel-size scoops, a broken ceramic jug.
But what caught Bram’s attention was a small animal skeleton on a slab of wood. The skull was crushed, pinned to the slab by a copper bar that was attached to a large spring. But enough could be seen of the jaw to show that it was still clenched around something that looked like a fossil nut, which was attached by a wire to a sort of pivoting tray.
“A trap,” Ame said. “The animal in it was a Cuddly.”
Shira tossed her lank hair back within the bowl of her helmet. “They poisoned them, too,” she said. “We’ve found piles of Cuddly bones around a feast of that same bait that one of them would have brought back to the burrow for the females and young ones.”
Bram was appalled. “But what a terrible thing to do.”
“No more terrible than what Original Man did to rats,” Jorv said.
“The longfoots carried their own vermin into space with them, just as man once carried rats and mice,” Ame said. “That’s what the vermin were. Cuddlies.”
“The Cuddlies’ ancestral form, actually,” Shira said. “They hadn’t evolved for airlessness yet. You can see that the rib cage isn’t enlarged for accessory lungs. And the toe of the rear foot is not fully opposable.”
“But I think that if we were to see one of these creatures in its fur,” Ame said, “we’d see it as a Cuddly.”
Bram studied the trap with distaste. “Ingenious and cruel,” he said. “The victim had to tug at the bait to pull it loose, and that released this strut that kept the spring armed. The animal’s head would be in position for the copper bar. Even if its reflexes were good and it drew back, it would still get its neck broken.”
“These little animals were pests,” Jorv said. “They got into the longfoots’ food supply. They were probably unsanitary. And they probably bit.”
“The longfoots tried diligently to exterminate them back on Earth. We found a sort of children’s picture book with a story about it. But the creatures must have been too clever, or too prolific, to be stamped out entirely. The longfoots must have been horrified to find that they’d transported them here.”
“Well, the Cuddlies outlasted the longfoots here, at any rate,” Bram said grimly. “Long after these … rat-people packed up and went back to Earth, The Cuddlies were able to survive on the diskworld long enough to adapt for vacuum. To adapt for space travel, when you stop to think about it—when you see the way they scamper around Yggdrasil’s branches and seem to enjoy it.”