She came a pace into the room, turned, closed the door behind her, and leaned back on her tail. “They’re all wingfingers,” she said.
Toroca nodded.
“And yet—I’m not a savant, Toroca. Explain it to me. Why should they all be wingfingers? Why are there no other kinds of animal here?” It was fairly cramped in this room that used to be Afsan’s quarters. Babnol had been standing as far away from Toroca as possible. Indeed, after a moment, she turned away, a common response to a feeling of crowding. She looked at the knotty planks making up the cabin wall.
“All right,” said Toroca, “I’ll try—but I’m not yet completely sure myself. Consider this: our world has one landmass, Land. It happens to be on the equator, which is the warmest part of the world. Most of the lifeforms that live there, regardless of whether they are warm-blooded or cold-blooded, have either scales or naked skin. In other words, next to no bodily insulation.”
“Insulation?”
“An external covering to keep heat in or the cold out. Like the thick snowsuits we wear here. But, of course, we don’t really need insulation back on Land. The climate there is always warm, and most of the warm-blooded animals are quite large.”
“I’m not following you, Toroca.”
“The larger you are, the less skin you have per unit volume. Since it’s through the skin that an animal can lose heat, large size is a good thing to have if you are an uninsulated warm-blooded animal. Body volume increases with the cube; skin surface area increases with the square.”
“You’ve lost me.”
“Sorry.” Toroca clicked his teeth. “I forget not everyone had my father for a teacher. The physics is not important; simply accept that large animals—and even we Quintaglios are large, compared to lizards and snakes—have less of a need for insulation. The mere fact of our bulk helps us keep a constant body temperature.”
“All right.”
“But wingfingers tend to be small. Yes, they may have huge wingspans, but the actual wingfinger torso is quite tiny. And wings, because they are almost all surface area and have practically no bulk, radiate heat at a great rate. Although wingfingers are warm-blooded, like us, they’d lose all their heat if they didn’t have insulation.”
“Fur!”
“Exactly. A wingfinger’s fur helps it retain its body heat. Now, consider this. Here at the south pole, it is cold—”
“I’ll say.”
“Indeed, it’s so cold that no amphibians or lizards or snakes are found here at all. The only cold-blooded animals are insects and fish in the waters. On the ice cap itself, there is not one single cold-blooded vertebrate. There cannot be, for cold-blooded vertebrates require heat from the sun, of which, as we’ve observed, there is precious little here.”
“I get it!” said Babnol. “Wingfingers have both the means to get from Land to here—by flying—and they have their furry body coverings to keep them warm!”
“Exactly. Only wingfingers could survive here. No cold-blooded vertebrate has a chance. No walking vertebrate could get here, and, even if one could, without insulation, it would die from exposure. Of all the animals in the world, only wingfingers are suited for this place.”
“But the creatures we’ve found here aren’t simple wingfingers.”
“No, they’re not.” Toroca gestured at the notes on his desk. “This is the part that I’m having difficulty with. The wingfingers that did fly here, no doubt countless kilodays ago—countless years ago—found an environment in which no other large animals lived. They had no predators here. Some were able to give up flying altogether and take up life on the ice surface. Others went further and learned to dive into the waters. What must have started out as standard flying wingfingers ended up as the wide range of animals we see here. Roles that would have been played by runningbeasts or blackdeaths back on land were unfilled here on the southern ice. Wingfingers seized the opportunities and took over those vacant roles, becoming lords not only of the air but of the ground and the waters as well.”
Babnol turned her head away from the wall and faced Toroca. Her teeth were clicking. “Why are you amused?” asked Toroca.
“Well, it’s a good story, my friend,” she said. “But it can’t be true. An animal cannot change from one thing into something else. What nonsense!”
“I am coming to believe that an animal can change,” said Toroca.
“How? I’ve never seen an animal change. Well, yes, I’ve seen tadpoles change into frogs, and larvae into adult insects, but that’s not the kind of change you’re talking about.”
“No, it’s not.”
“You’re talking about changing completely, from one… one…”
“One species.”
“From one species into another.”
“That’s right.”
Babnol’s teeth clicked again. “But how could that happen? A wingfinger can no more decide that it will grow swimming paddles than I can decide that I’ll grow wings. A thing is what it is.”
Toroca’s voice was soft. “Forgive me, dear Babnol, but have you looked at yourself in a mirror?”
Babnol’s tone suddenly grew as frosty as the air. “What’s that supposed to mean?”
“I mean, you have a horn growing from your muzzle.”
Defensive: “Yes. So?”
“Have you wondered how it got there?”
Babnol sighed. “Many times.”
“It’s a change, a novelty, something that’s never before existed. You have a characteristic that your parents lacked.”
“It was God’s will,” said Babnol, her muzzle, as usual, tilted haughtily up. “I do my best to accept it.”
Toroca thought about telling her how fascinating, how appealing, how attractive the growth was, but was afraid of what her reaction might be. Instead: “Don’t be angry, Babnol, but I think perhaps it has nothing to do with God. I have begun to suspect that changes can occur spontaneously. Usually such a change would be of no value one way or another: your retention of the birthing horn is neither a hindrance nor a help to you. It just is. Sometimes, though, a change might be undesirable. For instance, your horn could have completely obscured your vision. That would have been a terrible disadvantage. On the other hand, rarely, a change might be advantageous. If your horn were longer and perhaps placed slightly differently, it might make a formidable hunting aid.”
“It is just what it is,” said Babnol, still defensive. “No more, no less. You are making me uncomfortable talking about my deformity.” She turned back to face the wall.
Toroca instantly regretted using her as an example. “I’m sorry,” he said, wanting to reach out, to touch her, to soothe her hurt. “Let’s—let’s talk only of wingfingers, then. Consider one that arrived here, but had a thicker coat of fur than its companions. It would have an advantage over them. Likewise, a wingfinger with thick stubby wings—perhaps of little use for flying—might find they made very serviceable swimming paddles.”
Still facing the walclass="underline" “I suppose.”
“So you can see that the creatures here might have arisen from normal wingfingers.”
“Or,” said Babnol, “perhaps God just made them this way from the start.”
“But why on the body plan of a wingfinger?” asked Toroca.
“Why not?”
“Well, because it’s not efficient.”
Babnol’s tone showed she was still upset. “Using a tried-and-true design seems efficient to me. Our shipwrights do that, for instance.”
“But the wingfinger design is not efficient for anything except flying. Look at the paddles of a diver; they’re not nearly as effective as, say, the fins of a fish.”