Hunt considered the question for a few seconds.
“You mean that in today’s animals both processes are there, but all scrambled up together, but in the Oligocene species they’re separated out.”
“Yes.”
“All the Oligocene species?” Hunt asked after a moment’s further reflection. Danchekker nodded in satisfaction at seeing that Hunt was on the right track.
“Precisely, Vic. All of them.”
“That doesn’t really make sense. I mean, the first thing you’d think would be that some kind of mutation had occurred to change one form into the other-the scrambled-up form and the separated-out form. That could have happened either way around. In one case the scrambled form could be the ‘natural’ terrestrial pattern that became mutated on Minerva; that would explain why the animals from there have it and the descendants of the ones that were left here don’t. Alternatively, you could suppose that twenty-five million years ago the separated-out form was standard, which explains of course why the animals from that time exhibit it, but that in subsequent evolution here on Earth it changed itself into the scrambled form.” He looked across at Danchekker and threw his arms out wide. “But there’s one basic flaw in both those arguments-it happened in lots of different species, all at the same time.”
“Quite.” Danchekker nodded. “And, by all the principles of selection and evolution that we accept, that would appear to rule
out the possibility of any kind of mutation-natural mutation, anyway. It would be inconceivable for the same chance event to occur spontaneously and simultaneously in many distinct and unrelated lines. . . utterly inconceivable.”
“Natural mutation?” Hunt looked puzzled. “What are you saying then?”
“It’s perfectly simple. We’ve just agreed that the difference couldn’t be due to ordinary natural mutation, but nevertheless it’s there. The only other explanation possible then is that it was not natural.”
Impossible thoughts flashed through Hunt’s mind. Danchekker read the expression on his face and voiced them for him.
“In other words they didn’t just happen; they were made to happen. The genetic codings were deliberately rearranged. We are talking about an artificial mutation.”
For a moment Hunt was stunned. The word deliberate denoted conscious volition, which in turn implied an intelligence.
Danchekker nodded again to confirm his thoughts. “If I may rephrase your question of a minute ago, what we are really asking is, did the animals that were shipped to Minerva change, or did the animals that were left on Earth change after the others were shipped? Now add to the equation the further fact that we have established-that somebody deliberately caused the change to happen-and we are left with only one choice.”
Hunt completed the argument for him. “There hasn’t been anybody around on Earth during the last twenty-five million years that could have done it, so it must have been done on Minerva. That can only mean. . .” His voice trailed off as the full implication became clear.
“The Ganymeans!” Danchekker said. He allowed some time for this to sink in and then continued. “The Ganymeans altered the genetic coding of the terrestrial animals that they took back to their own planet. I am fairly certain that the samples that were recovered from the ship at Pithead were descendants of a strain that had been mutated in this way and had faithfully carried on the mutation in themselves. This is the only logical conclusion that can be drawn from the evidence we have reviewed. Also, it is strongly supported by another interesting piece of evidence.”
By now Hunt was ready for anything.
“Oh?” he replied. “What?”
“That strange enzyme that turned up in all of the Oligocene species,” Danchekker said. “We know now what it did.” The look on Hunt’s face asked all the questions for him. Danchekker continued: “That enzyme was constructed for one specific task. It cleaved the DNA chain at precisely the point where those two coding groups were joined-in species where they were separated out, of course. In other words, it isolated the genetic code that defined the C02-tolerance characteristics.”
“Okay,” Hunt said slowly, but still not following the argument fully. “I’ll take your word for that. . . . But how does that support what you just said about the Ganymeans? I’m not quite-“