“We all believe there’s a deeper reason than that,” Hunt said candidly. “We in this room might come from different origins, but first and foremost we are all scientists. Truth is our business and we shouldn’t shy away from the facts. This is an informal occasion and we all know each other pretty well now. We’d like you to be frank. We’re curious.”
The air became charged with expectancy. Shilohin looked again toward Monchar, who quietly signaled his acquiescence. She downed the last of her drink slowly as she collected her thoughts, then looked up to address the room.
“Very well. Perhaps, as you say, we would do better without any secrets. There was one crucial difference between the patterns of natural evolution that unfolded on your world and on our world-on Minerva there were no carnivores.” She paused as if waiting for a response, but the Earthmen continued to sit in silence; obviously there was more to come. She felt a twinge of sudden relief inside. Perhaps the Ganymeans had been overapprehensive of the possible reactions of these unpredictable and violently inclined dwarves after all.
“The basic reason for this difference, believe it or not, lay in the fact that Minerva was much farther away from the Sun.” She went on to explain. “Life could never have developed on Minerva at all without the greenhouse effect, which you already know about. Even so, it was a cold planet, certainly in comparison to Earth.
“But this greenhouse effect kept the Minervan oceans in a liquid state and, as on Earth, life first appeared in the shallower parts of the oceans. Conditions there did not favor progression toward higher forms of life as much as on the warmer Earth; the evolutionary process was relatively slow.”
“But intelligence appeared there much earlier than it did on Earth,” somebody tossed in. “Seems a little strange.”
“Only because Minerva was further from the Sun and cooled more quickly,” Shilohin replied. “That meant that life got off to an early start there.”
“Okay.”
She resumed. “The patterns of evolution on the two worlds were remarkably similar to start with. Complex proteins appeared, leading eventually to self-replicating molecules, which in time led to the formation of living cells. Unicellular forms came first, then colonies of cells and after them multicelled organisms with spe
cialized features-all of them variations on the basic marine invertebrate form.
“The point of departure at which the two lines went their own way, each in response to the conditions prevailing on its own planet, was marked by the appearance of marine vertebrates- boned fishes. This stage marked a plateau beyond which the Minervan species couldn’t progress toward anything higher until they had solved a fundamental problem that was not faced by their counterparts on Earth. The problem was simply their colder environment.
“You see, as improvements appeared in the Minervan fish species, the improved body processes and more highly refined organs demanded more oxygen. But the demand was already high because of the lower temperature. The primitive circulatory systems of the early Minervan fish couldn’t cope with the dual workload of carrying enough oxygen to the cells, and of carrying wastes and toxins away from the cells-not if progress toward anything more advanced was going to be made, anyway.”
Shilohin paused again to invite questions. Her listeners were too intrigued, however, to interrupt her story at that point.
“As always happens in situations like that,” she continued, “Nature tried a number of alternatives to find a way around the problem. The most successful experiment took the form of a secondary circulation system developing alongside the first to permit load-sharing-a completely duplicated network of branching ducts and vessels; thus, the primary system concentrated exclusively on circulating blood and delivering oxygen, while the secondary took over fully the job of removing the toxins.”
“How extraordinary!” Danchekker could not help exclaiming.
“Yes, I suppose that when judged by the things you’re used to it was, Professor.”
“One thing-how did the different substances find their way in and out of the right system?”
“Osmotic membranes. Do you want me to go into detail now?”
“No, er, thank you.” Danchekker held up a hand. “That can wait until another time. Please continue.”