“Maybe they’d be more like us yet, except for Anu’s going off on a red giant kick about a billion years ago. It’s spent the whole while since growing bigger, and nastier each time it passes close. This means poikilothermic land animals—whoops! Cold-blooded, if you prefer—they’ve been at a still worse disadvantage than on Earth, and never got far. No trace among the fossils of anything analogous to dinosaurs. The theroids grabbed an early lead and kept it.
“Okay. On this basis, which you’re doubtless familiar with already but I wanted to spell out—on this basis, we think—we think, mind you; the actual evidence to date is pitifully slight—we think the theroids have had more time to evolve than mammals on Earth. (Yes, I realize mammals are very old, but they didn’t really take off till the Oligocene.) The trick they invented here that we haven’t, is symbiosis. Oh, sure, you’re symbiotic with a few organisms yourself, like your intestinal flora. One definition would even include your mitochondria. But the well-developed Ishtarian theroid is a whole zoo and botanical garden of co-operating species.
“Let’s take a sophont, for instance—a few of his most conspicuous partners. His pelt, or hers, is a mossy plant, shallowly rooted in the skin but connected to the bloodstream… because his skin is a lot more complicated than ours. His mane and brows resemble ivy. Their branches make a tough armor for the upper backbone and a fairly thin skull. The plants take out carbon dioxide, water, and other by-products of animal metabolism for their own use. They give back oxygen directly, plus a whole string of vitamin-like materials we’ve barely started to identify. True, the plants don’t furnish a complete respiratory-eliminative system. They supplement lungs, double heart, intestines, every organ—all of these with their special symbionts—but the upshot is an individual who functions better than we do. He can live on a far wider variety of food. He’s less extravagant of water, through sweat or wastes or simply breathing. Thanks to Anu, water is in short supply over large areas of Ishtar. And, ah, our native also carries a built-in emergency food supply, those same plants. He can eat them and still survive, however handicapped by the lack. They’ll soon grow back from their roots or from spores in air and soil, same as they do on the newly born.”
Jill paused for air. “Whew!”
“I can see the advantages,” Dejerine said slowly.
“Did you know this already?”
“I have read, yes. However, I’m glad to hear it repeated in a larger context.”
“I’m coming to one, I hope.” Caught in an excitement which for her never faded, Jill said: “Those advantages go beyond the obvious. Look, symbiosis like this isn’t merely helpful directly. It frees genes.” Observing his puzzlement: “Well, think. Genes, which Ishtarian life also has, genes store information. Their storage capacity is bodacious, but it isn’t infinite. Imagine a set of ’em which governs some metabolic function. Now imagine that function being taken over by your friendly neighborhood symbiont. The genes aren’t needed for it any more, They can go into new lines of work. Mutation and selection see to it that they do. The mutation rate’s probably higher among Ishtarian theroids than Terrestrial mammals anyway, because body temperature is. The problem on Ishtar is much oftener keeping cool than keeping warm; and the theroids solve it partly through their plants—assorted endothermic chemistry more than transportation—and partly by being naturally warm themselves… I’m digressing all over the place, hm? Well, nature does. The point I’m trying to make is that the Ishtarians have advantages over us, including a longer evolutionary history as homeothermic animals. They may not have reached their present level of intelligence as early as humans—though Lord knows when that was— but they phased into it more gradually. This is one reason those goblins are still around. And the history shows. It shows.”
Dejerine frowned. “In their brains, do you mean?” he asked.
Jill nodded. The ends of her hair tickled the bare angles between neck and shoulders. “Nervous systems as a whole,” she said. Man is rather hastily built, you realize. Jerry-built, even. It’s been said we have three brains, one cobbled on top of the next. The stem first, the reptilian brain; then the mammalian cerebellum; finally the overdeveloped cerebral cortex. They don’t work together in awfully good harmony—hence ax murders, mobs, and socialism. The Ishtarian has more unity in his head. You can see it if you do a dissection. Insanity seems to be unknown—literally doesn’t exist, unless you count amentia due to massive physical damage. Not to disease. Ishtarians have precious little disease, with all those specialized helpers living in them. As for neurosis—” Jill shrugged. “That’s a matter of definition, isn’t it? I’ll just say I’ve never known an Ishtarian whom I would call a twitch. And I might point out that alien and powerful as we happen to be, we humans have never produced any culture shock here. They respect us, they accept from us what things and ideas they find useful, but it all integrates easily with their old ways.”
Hoarse and a trifle dizzy from rapid-fire talking, she leaned back against the trunk which supported Dejerine, sipped coffee grown cold in the cup, a bite from her piece of bread and jam. She’d made the preserve at home, half strawberry, half native newton fig, and been pleased when the Earthling wanted seconds.
“M-m-m,” he mused, “no doubt the general life-physiological superiority accounts for the long Ishtarian life-span. Three to five hundred years, correct?”
Jill nodded. “I think, though, another factor’s been at work as well,” she said. “On Earth, fairly short generations mean fast genetic turnover, fast evolution. That should be an advantage for the species. I’m inclined to agree with the theory that we’re programmed to start seriously aging as early as about forty, for this exact reason. But Ishtar suffers these Anu passages every thousand years. The effects are powerful for only a century or so. Longevity probably helps conserve adaptations to the cycle, and thereby helps species survival.”
He gave her a considering look. “What a bleak philosophy.”
“Oh? Doesn’t bother me.” Jill thought for a moment, Okay, let’s be frank with him. We need his… empathy… more than his intellectual understanding. “Well, no use denying, everybody’d like to have that number of healthy years,” she said. “But since we can’t, no use crying, either. The Ishtarians get their share of woe. Every second lifetime, Ragnarok. And they don’t whine.”
He was silent awhile, in the blowing morning warmth, before he murmured, with his eyes aimed away from her, across the curve of the planet: “It must have curious effects on you in Primavera. The same unchanged centaur who was your grandfather’s friend is yours, and will be your children’s—but before you were grown, he was your teacher for many things, was he not, your protector, conceivably your idol? Forgive me; I do not wish to be impertinent; but I am interested to know if my guess is right, that for some of your lifelong residents, some autochthons are father figures.”
By Darwin, he is a surprising bastard!
His gaze back upon her, he must have seen he had touched a nerve. Why deny what he could learn by leading any gossipy townsperson into talk? “Yes, I s’pose,” Jill said. “Maybe I’m an example. Larreka, the commandant of the Zera Victrix… we’ve always been close. I daresay I absorbed a lot of attitudes from him.” Impulsively: “He saw me through a bad experience in a way nobody else in the universe could’ve.”