Hunt just continued to stare in horrified silence as the picture unfolded before his mind's eye.

"That's what wiped them all out," he said at last. "That poor bloody Minervan zoo wouldn't have had a chance. No wonder it didn't last for more than a few generations after the Ganymeans disappeared from the scene."

"With another consequence as well," Danchekker came in. "The terrestrial carnivores concentrated on the most readily available prey--the native species--and so gave the terrestrial herbivores a breathing space to increase their numbers and become firmly established. By the time the Minervan natives had been wiped out the carnivores would have been forced to revert to their old habits, but by that time the situation would have stabilized. A mixed and balanced terrestrial animal ecology had been given time to establish itself across Minerva. . . ." The professor's voice took on a soft and curious tone. "And that is the way things must have remained . . . right on through until the time of the Lunarians."

"Charlie. . ." Hunt sensed that Danchekker was at last hinting at something he had been building up to all along. "Charlie," Hunt repeated. "You found that same enzyme in him too, didn't you?"

'We did, but in a somewhat degenerate form. . . as if it were in the last phases of fading away completely. It did fade away of course, since Man no longer possesses it. . . . But the interesting point, as you say, is that Charlie had it and so, presumably, did the rest of the Lunarians."

"And there was only one place for it to come from. . ."

"Precisely."

Hunt raised a hand to his brow as the full import of these revelations hit him. He turned slowly to meet Danchekker's solemn gaze and then slowly, his features knotted into a mask of disbelief that strove to reject the things that reason now stripped bare, sank weakly down onto an arm of the nearest chair. Danchekker said nothing, waiting for Hunt to put the pieces together for himself.

"The population on Minerva included samples of the latest Oligocene primates," Hunt said after a while. "They were almost certainly as advanced as anything that Earth had produced at the time, and with the greatest potential for advancing further. The Ganymeans had unwittingly removed the inhibition on further brain development. . . ." He looked up and met Danchekker's imperturbable stare again. "They'd have raced ahead from there. There was nothing to stop them. And with their aggressive streak unleashed as well. . . a whole race of runaway mutants. . . psychological Frankenstein monsters. . . ."

"Which is, of course, where the Lunarians came from," Danchekker said. His voice was grave. "By rights they shouldn't have survived. All the theories and models of the Ganymean scientists said that they would inevitably destroy themselves. They almost did. They turned a whole planet into one vast fortress and by the time they had developed technology their lives revolved around unceasing warfare and the ruthless, uncompromising determination to exterminate all other rival states. They were capable of conceiving no other formula to solve their problems. In the end they did indeed destroy themselves and Minerva along with them, at least, they destroyed their civilization, if that is the correct term for it. They should have destroyed themselves totally, but, by a million-to-one chance, it did not quite happen. . . ." Danchekker looked up and left Hunt to fill in the rest.

But Hunt just sat and stared, overwhelmed. After the nuclear holocaust between the opposing forces of the two remaining Lunarian superstates had altered permanently the face of Minerva's moon and Minerva had disintegrated, the moon fell inward toward the Sun to be captured by Earth. The tiny band of survivors carried with it had possessed the resources to set off one last, desperate journey--to the surface of the new world that now hung in the sky above their heads. For forty thousand years the descendants of those survivors had merged into the survival struggle of Earth, but eventually they had spread all over the planet and emerged as an adversary as formidable as their ancestors had been on Minerva.

At last, Danchekker resumed quietly. "We have speculated for some time now that the Lunarians, and hence Man, originated from an unprecedented mutation that must have occurred somewhere along the primate line that was isolated on Minerva. Also, we have noted that somewhere along his line of ancestry, Man has somehow abandoned the self-immunization process that other animals have in common. Now we see not only proof that these things were true, but also how they came about. In fact, many species went along that same path, but all bar one were destroyed when Minerva was destroyed. Only one--Man in the form of the Lunarians--came back again." Danchekker paused and took a long breath. "An unprecedented mutation did indeed occur on Minerva, but it was not a natural mutation. Modern Man exhibits fewer of the extremes that drove the Lunarians to their doom, thankfully, but all the same the legacy of our ancestry is written through the pages of our history. Homo sapiens is the end-product of an unsuccessful series of Ganymean genetic experiments!

"The Ganymeans believe that Man is slowly but surely recovering from the instability and compulsive violence that destroyed the Lunarians. Let us hope they are right."

Neither man said anything more for a long time. It was ironic, Hunt thought, that after all the Ganymeans had said, their own kind should turn out to be the prime cause of all the things that had come to pass over the last twenty-five miffion years. And throughout all that time, while primates evolved into sapient beings on Minerva, and the Lunarian civilization came and went, and fifty thousand years of human history were being acted out on Earth, the Shapieron had been out there in the void, preserved by the mysterious workings of the laws that distort time and space.

"An unsuccessful series of Ganymean genetic experiments," Hunt echoed Danchekker. "They started the whole thing. They came back to find us flying spaceships and building fusion plants, and they thought our rate of progress was miraculous. And all the time they'd started the whole thing off in their own labs, twenty-five million years ago. . . and given it up as a bad job! It's funny when you think about it, Chris. It's damned funny. And now they've gone for good. I wonder what they would have said if they'd only known what we know now."

Danchekker did not reply at once, but stared thoughtfully at the top of his desk for a while, as if weighing whether or not to say what was going through his head. In the end he stretched an arm forward and began toying idly with a pen. When he spoke he did not engage Hunt's eyes directly but continued to watch the pen tumbling over and over between his fingers.

"You know, Vic, in the last months before they went, the Ganymeans became very interested in all aspects of terrestrial biochemistry, including all our available data on Charlie, Man, and the Oligocene animals from Pithead. For a long time they were bubbling over with curiosity and ZORAC couldn't find enough questions to ask about such matters. And then, about a month ago, they suddenly became very quiet about it all. They hadn't even mentioned it since."

The professor looked up and confronted Hunt with a direct and candid stare.

"I think I know why," he said, very softly. "You see, Vic, they knew all right. They knew. They knew that they had brought a pathetically deformed creature into a hostile universe and left it to fend for itself against odds that were hopeless, and they returned and saw what that creature had become--a proud and triumphant conqueror that laughs its defiance at anything the universe cares to throw at it. That is why they are gone. They believe that they owe it to Man to leave him free to perfect the world that he has built for himself in whatever way he chooses. They know what we were and they see what we have made of ourselves since. They feel that we have suffered enough interference in the past and have shown ourselves to be the better managers of our own destiny."