“Okay, point taken,” Hunt conceded. “But what could they do about it?”
“Somewhere around the time that I was describing-the early
beginnings of civilization-the ancients discovered that the poisons in the secondary system could be neutralized by including certain plants and molds in their diet. They discovered this by observing the habfts of some animals whose immunity to damage that should have meant certain death was well known. That simple step was probably their biggest single leap forward. Coupled with their inteffigence it virtually insured dominance over all forms of Miner-van life. It opened up the whole of medical science, for example. With their self-poisoning mechanism defused, surgery became possible. At a later stage in their history they developed a simple surgical method of neutralizing the secondary system permanently without having to rely on drugs. It became standard practice for every Ganymean to be treated in this way soon after birth. Even later still, when they had progressed to a level beyond ours, they isolated the gene that caused the secondary system to develop in the fetus in the first place and eradicated it completely. They literally bred this trait out of themselves. None of the Ganymeans we’ve met was born with a secondary system at all, and neither were quite a few generations before them. Rather an elegant solution, don’t you think?”
“Incredible,” Hunt agreed. “I’ve never had a chance to talk about that kind of thing with them. . . not yet anyway.”
“Oh, yes.” Danchekker nodded. “They were extremely proficient genetic engineers, were our Ganymean friends. . . very proficient.”
Hunt thought for a second and then snapped his fingers in sudden comprehension.
“But of course,” he said. “In doing that they buggered their CO2 tolerance too.”
“Precisely, Vic. All the other animals on Minerva retained the high natural tolerance. Only the Ganymeans were different; they sacrificed it in exchange for accident-resistance.”
“But I don’t see how they could,” Hunt said, frowning again. “I mean, I can see how they did it, but I don’t see how they could get away with it. They must have needed the CO2 tolerance, otherwise they wouldn’t have evolved it in the first place. They must have known that too. Surely they weren’t stupid.”
Danchekker nodded as if he already knew what Hunt was going to say.
“That probably wasn’t so obvious at the time,” he said. “You
see, the composition of the Minervan atmosphere fluctuated through the ages much the same as that of Earth has. From vanous researches the Ganymeans established that at the time land life first emerged, volcanic activity was at a peak and the level of CO2 was very high; naturally, therefore, the earliest species developed a high resistance. But as time went on the level decreased progressively and appeared to have stabilized itself by the time of the Ganymeans. They came to regard their tolerance mechanism as an ancient relic of conditions that no longer existed and their experiences showed that they could get by without it. The margin was small-the CO2 level was still high by our standards-but they could manage. So, they decided to do away with it permanently.”
“Ah, but then the level started going up again,” Hunt guessed. “Suddenly and catastrophically,” Danchekker confirmed. “On a geological time scale anyway. They were in no immediate danger, but all their measurements and calculations indicated that if the rate of increase went on, they-or their descendants one day anyway-would be in trouble. They would be unable to survive without their ancient tolerance mechanism, but they had eliminated that mechanism from their race. All the other animals would have no difficulty in adapting, but the Ganymeans were somewhat stuck.”
The full magnitude of the problem that had confronted the Ganymeans dawned on Hunt at last. They had bought a one-way ticket out of the hard-labor camp only to find that it led to the death cell.
“What could they do?” Danchekker asked, and then went on to answer the question for himself. “First-use their technology to hold the CO2 level down by artificial means. They thought of that but their models couldn’t guarantee them a tight enough measure of control over the process. There was a high risk that they’d end up freezing the whole planet solid and, being the cautious breed that they were, they elected not to try it-at least not until it was a last-resort measure.