When no one seemed ready to object, Danchekker forged ahead. “But in every case there was one exception-this enzyme. Everything tells us that if this enzyme were present in the ancestor, then it, or something very like it, should be readily observable in the descendants. Yet in every case the results have been negative. I say that cannot happen, and yet it has happened.”
A brief silence descended while the group digested Danchekker’s words. At length Sandy Holmes ventured a thought. “Couldn’t it still be a radical mutation, but the other way around?”
Danchekker frowned at her.
“How do you mean, the other way around?” asked Henri Rousson, another senior biologist, seated next to Carpenter.
“Well,” she replied, “all the animals on the ship had been to Minerva, hadn’t they? Most likely they were born there from ancestors the Ganymeans had transported from Earth. Couldn’t something in the Minervan environment have caused a mutation that resulted in this enzyme? At least that would explain why none of today’s terrestrial animals have it. They’ve never been to Minerva and neither have any of the ancestors they’ve descended from.”
“Same problem,” Fichter muttered, shaking his head.
“What problem?” she asked.
“The fact that the same enzyme was found in many different and nonrelated Oligocene species,” Danchekker said. “Yes, I’ll grant that differences in the Minervan environment could mutate some strain of enzyme brought in from Earth into something like that.” He pointed at the screen again. “But many different species were brought in from Earth-different species each with its own characteristic metabolism and particular groups of enzyme strains. Now suppose that something in the Minervan environment caused those enzymes-different enzymes-to mutate. Are you seriously suggesting that they would all mutate independently into the same end-product?” He waited for a second. “Because that is exactly the situation that confronts us. The Ganymean ship contained many preserved specimens of different species, but every one of those species possessed precisely the same enzyme. Now do you want to reconsider your suggestion?”
The woman looked helplessly at the table for a second, then made a gesture of resignation. “Okay. . . If you put it like that, I guess it doesn’t make sense.”
“Thank you,” Danchekker acknowledged stonily.
Henri Rousson leaned forward and poured himself a glass of water from the pitcher standing in the center of the table. He took a long drink while the others continued to stare thoughtfully through the walls or at the ceiling.
“Let’s go back to basics for a second and see if that gets us anywhere,” he said. ‘We know that the Ganymeans evolved on Minerva-right?” The heads around him nodded in assent. “We also know that the Ganymeans must have visited Earth because there’s no other way they could have ended up with terrestrial animals on board their ship-unless we’re going to invent another hypothetical alien race and I’m sure not going to do that because there’s no
reason to. Also, we know that the ship found here on Ganymede had come to Ganymede from Minerva, not directly from Earth. If the ship came from Minerva, the terrestrial animals must have come from Minerva too. That supports the idea we’ve already got that the Ganymeans were shipping all kinds of life forms from Earth to Minerva for some reason.”
Paul Carpenter held up a hand. “Hang on a second. How do we know that the ship downstairs came here from Minerva?”
“The plants,” Fichter reminded him.
“Oh yeah, the plants. I forgot. . .” Carpenter subsided into silence.
The pens and animal cages in the Ganymean ship had contained vegetable feed and floor-covering materials that had remained perfectly preserved under the ice coating formed when the ship’s atmosphere froze and the moisture condensed out. Using seeds recovered from this material, Danchekker had succeeded in cultivating live plants completely different from anything that had ever grown on Earth, presumed to be examples of native Minervan botany. The leaves were very dark-almost black-and absorbed every available scrap of sunlight, right across the visible spectrum. This seemed to tie in nicely with independently obtained evidence of Minerva’s great distance from the Sun.
“How far,” Rousson asked, “have we got in figuring out why the Ganymeans were shipping all the animals in?” He spread his arms wide. “There had to be a reason. How far are we getting on that one? I don’t know, but the enzyme might have something to do with it.”