"Exactly."
"And what was the purpose of it all?" Hunt was becoming visibly excited. "Any ideas on that?"
"Yes," Danchekker replied. "I think we have. In fact the things that we have just considered tell us all that we need to know to guess at what they were up to." He sat back and interlaced his fingers again. "With the enzyme performing in the way that I have just described, the object of the exercise becomes clear. At least I think it does. . . . If the animals that possessed the already altered DNA were implanted with the enzymes, the chromosomes in their reproductive cells would have been modified. This would have made it possible for a strain of offspring to be bred from them who possessed the CO2 coding in the form of an isolated, compact unit that could be manipulated and'got at' with comparative ease. If you like, it enabled this particular characteristic to be separated out, perhaps with a view to its becoming the focal point of further experiments with later generations. . . ." Danchekker's voice took on a curious note as he uttered the last few words, as if he were hinting that the main implication of his dissertation was about to emerge.
"I can see what you're saying," Hunt told him. "But not quite why. What were they up to then?"
"That was how they sought to solve their environmental problem after all else had failed," Danchekker said. "It must have been something that was thought of during the later period of Ganymean history on Minerva--sometime after the Shapieron went to Iscaris, otherwise Shilohin and the others would have known about it."
"What was how they sought to solve it? Sorry, Chris, I'm afraid I'm not with you all the way yet."
"Let us recapitulate for a moment on their situation," Danchekker suggested. "They knew that the CO2 level on Minerva had begun to rise, and that one day it would reach a point that they would be unable to withstand; the other Minervan native species would be unaffected, but the Ganymeans would be vulnerable as a consequence of their breeding their original tolerance out of themselves as part of the trade-off for better accident-resistance. They lost it when they took the decision to dispense permanently with their secondary circulation systems. They declined climatic engineering as a solution and tried migration to Earth and the Iscaris experiment but both failed. Later on, it appears, they must have tried something else."
Hunt was all ears. He made a gesture of total capitulation and said simply, "Go on."
"One thing that they did discover on Earth, however, was a family of life that had evolved from origins in a warmer environment than that of Minerva, and which had not had to contend with the load-sharing problem that had caused the double-circulatory-system architecture to become standard on their own planet. Of particular interest, terrestrial life had evolved a completely different mechanism for dealing with carbon dioxide--one that did not depend on any secondary circulation system."
Hunt looked incredulous. He stared at Danchekker for a second while the professor waited for the response.
"You're not trying to say. . . they didn't try and pinch it?"
Danchekker nodded. "If my suspicions are anything to go by, that is exactly what they tried to do. The animals from Earth were transported back to Minerva for the purpose of large-scale genetic experiments. The object of those experiments, I believe, was threefold: first, to modify the DNA coding in such a way that the C02 -tolerance portion became separated out from the scrambled form--as you put it--that had evolved naturally on Earth; second, to perfect a means--the enzyme--of isolating that block of code and passing it on in an intact and workable unit to later strains; third, but this is a guess, to implant those codes into Minervan animals in an attempt to find out if a Minervan life form could be modified into developing a mechanism for dealing with carbon dioxide that did not depend on its secondary system. We have evidence that they achieved the first two of these objectives; the third must necessarily remain speculative, at least for the time being."
"And if they did succeed in the third, then the next step would be. . ." Hunt's voice trailed off again. The sheer ingenuity of the Ganymean scheme made it difficult for him to accept it unquestioningly.
"If it worked, and if there were no undesirable side effects, the intention was no doubt to engineer the same codes into themselves," Danchekker confirmed. "Thus they would enjoy an in-built tolerance that would happily continue to perpetuate itself through succeeding generations, while at the same time preserving all the advantages that they had already gained by doing away with their secondary systems. A fascinating example of what intelligence can do to improve on Nature when natural evolution throws up a solution that leaves much to be desired, don't you think?"
Hunt rose from his chair and began pacing slowly from one side of the office to the other as he marveled at the sheer audacity of even conceiving such a scheme. The Ganymeans had expressed wonder at Man's readiness to meet Nature head-on in every challenge, but here was something, surely, that Man would have balked at. The basic instincts of the Ganymeans steered them away from physical danger, conflict and the like, but their thirst for intellectual adventure and combat, it appeared, was unquenchable; that was the spur that had driven them to the stars. Danchekker watched in silence, waiting for the question that he knew would come next. At length Hunt stopped and wheeled to face the desk.
"Yes, it was neat, all right," he agreed. "But it didn't work, did it, Chris?"
"Regrettably, no," Danchekker conceded. "But not for reasons for which, I feel, they were really to blame. We might have some catching up to do with them technically, but nevertheless I believe that we are in a position to see where they went wrong." He didn't wait for the obvious question at that point but went on. "We have the advantage of knowing far more than they possibly could have about life on our own planet. We have access to the work of thousands of scientists who have studied the subject for centuries, but the Ganymeans who came here twenty-five million years ago did not. In particular, they could not have known what Professor Tatham and his team at Cambridge have only just discovered."
"The scrambling together of the self-immunization and the CO2 -tolerance codings?"
"Yes, exactly that. The thing that the Ganymean genetic engineers would never have realized was that in isolating the latter, in order to make their proposed later experiments simpler, they were losing the former. Because of the method they adopted, the descendant strains that they bred would have been ideal subjects for further C02 -tolerance research, but they would also have lost their self-immunization capabilities. In other words, the Ganymeans created and raised a whole range of mixed terrestrial animal species that possessed no trace of the age-old mechanism for stimulating their own defensive processes by flooding the body with mild doses of pollutants--a mechanism which we still see today in the descendants of the animals that remained on Earth to continue evolving naturally, of course."