Hunt found Danchekker in his lab fussing over his Minervan plants, which by this time were proliferating in every corner of the room and seemed set to embark on an invasion of the corridor outside. The subject that the professor wanted to discuss was the theory that he and Hunt had formulated jointly, before the arrival
of the Ganymeans, concerning the low inherent tolerance of all Minervan land-dwelling species to atmospheric carbon dioxide. This theory held that the trait had been inherited, along with the basic system of chemical metabolism, from some very early, common, marine ancestor. After discussing the matter at some length with various Ganymean scientists through ZORAC, Danchekker now knew that this theory was wrong.
“In fact, when land dwellers eventually appeared on Minerva, they evolved a very efficient method of coping with the planet’s high carbon-dioxide level. The way in which they did it was one which, with the benefit of hindsight, was very obvious and very simple.” Danchekker stopped rummaging around among the mass of leaves for a moment and half turned his head to allow Hunt time to reflect on the statement. Hunt, perched casually on one of the stools with an elbow resting on the edge of the bench beside him, said nothing and waited.
“They adapted their secondary circulation systems to absorb the excess,” Danchekker told him. “Systems that had evolved specifically to remove toxins in the first place. They provided a ready-made mechanism ideal for the job.”
Hunt turned the proposition over in his mind and rubbed his chin thoughtfully.
“So . . .” he said after a while. “This idea we had that they all inherited a low tolerance was way off the rails. . . all baloney.”
“Baloney.”
“And this characteristic stayed, did it? I mean, all the species that came later inherited the mechanism . . . they were all well adapted to their environment?”
“Yes. Perfectly adequately.”
“But there’s still something I don’t see yet,” Hunt said, frowning. “If what you’ve just said was true, the Ganymeans should have inherited an adequate resistance too. If they did, they wouldn’t have had a CO2 problem. But they themselves said they did have a CO2 problem. So how come?”
Danchekker turned to face him and wiped his palms on the front of his lab coat. He beamed through his spectacles and showed his teeth.
“They did inherit it . . . the resistance mechanism. They did have a problem too. But, you see, the problem wasn’t natural; it
was artificial. They brought it upon themselves, far later in their history.”
“Chris, you’re talking in riddles. Why not start at the beginning?”
“Very well.” Danchekker began wiping dry the tools he had been using and replaced them in one of the drawers as he spoke. “As I said a moment ago, when land-dwelling life appeared on Minerva, the secondary circulation systems that all species already possessed-which caused them to be poisonous-adapted to absorb the excess carbon dioxide. Thus although Minervan air was high in carbon dioxide compared to that of Earth, all the forms of life that emerged there flourished quite happily since they had evolved a perfectly good means of adapting to their surroundings .
which is the way one would expect Nature to work. When, after hundreds of millions of years, intelligence emerged in the form of primitive Ganymeans, they too possessed the same basic architecture, which had remained essentially unchanged. So far so good?”
“They were still poisonous and they were well adapted,” Hunt said.
“Quite so.”
“What happened then?”
“Then a very interesting thing must have happened. The Ganymean race appeared and went through all the stages you would expect of a primitive culture beginning to grope its way toward civilization-making tools, growing food, building houses and so on. Well, by this time, as you might imagine, the ancient self-defense that they had inherited from their remote marine ancestors for protecting them against carnivores was turning out to be more of a damned nuisance than a help. There were no carnivores to be protected from and ft was soon obvious that none were likely to appear. On the other hand, the acute accident-proneness that resulted from self-poisoning was proving to be a severe handicap.” Danchekker held up a finger to show a small band of adhesive plaster around the second joint. “I nicked myself with a scalpel yesterday,” he commented. “Had I been one of those early Ganymeans, I would most probably have been dead within the hour.”