He blinked thoughtfully at the ceiling for a moment, then folded his hands across his small paunch and closed his eyes.
When he spoke again, he was speaking to himself:
“Assume a planet, somewhat earthlike, but not quite.
It has carboniferous life forms, but not human. Warm blooded, probably, and semi-intelligent.
And the planet has something else—it has an overabundance of parasite forms.
Actually, the various types of parasites are the dominant species. The warm blooded animals are the parasites’ vegetables, so to speak.
Now, during two billion years, say, of survival contests between parasite species, some parasites are quite likely to develop some curious methods of adaption. Methods of insuring the food supply—animals, who must have been taking a beating.”
Seevers glanced down from the ceiling.
“Tell me, youngster, what major activity did Man invent to secure his vegetable food supply?”
“Agriculture?”
“Certainly.
Man is a parasite, as far as vegetables are concerned.
But he learned to eat his cake and have it, too.
He learned to perpetuate the species he was devouring.
A very remarkable idea, if you stop to think about it.
Very!”
“I don’t see—”
“Hush!
Now, let’s suppose that one species of micro-parasites on our hypothetical planet learned, through long evolutionary processes, to stimulate regrowth in the animal tissue they devoured.
Through exuding controlled amounts of growth hormone, I think.
Quite an advancement, eh?”
Paul had begun leaning forward tensely.
“But it’s only the first step.
It let the host live longer, although not pleasantly, I imagine.
The growth control would be clumsy at first.
But soon, all parasite-species either learned to do it, or died out.
Then came the contest for the best kind of control.
The parasites who kept their hosts in the best physical condition naturally did a better job of survival—since the parasite-ascendancy had cut down on the food supply, just as Man wastes his own resources.
And since animals were contending among themselves for a place in the sun, it was to the parasite’s advantage to help insure the survival of his host-species—through growth control.”
Seevers winked solemnly.
“Now begins the downfall of the parasites—their decadence.
They concentrated all their efforts along the lines of… uh… scientific farming, you might say.
They began growing various sorts of defense and attack weapons for their hosts—weird biodevices, perhaps. Horns, swords, fangs, stingers, poisonthrowers—we can only guess.
But eventually, one group of parasites hit upon—what?”
Paul, who was beginning to stir uneasily, could only stammer.
Where was Seevers getting all this?
“Say it!” the scientist demanded.
“The… nervous system?”
“That’s right.
You don’t need to whisper it.
The nervous system.
It was probably an unsuccessful parasite at first, because nerve tissue grows slowly.
And it’s a long stretch of evolution between a microspecies which could stimulate nerve growth and one which could direct and utilize that growth for the host’s advantage—and for its own.
But at last, after a long struggle, our little species gets there.
It begins sharpening the host’s senses, building up complex senses from aggregates of old style receptors, and increasing the host’s intelligence within limits.”
Seevers grinned mischievously.
“Comes a planetary shake-up of the first magnitude.
Such parasites would naturally pick the host species with the highest intelligence to begin with. With the extra boost, this brainy animal quickly beats down its own enemies, and consequently the enemies of its microbenefactor.
It puts itself in much the same position that Man’s in on Earth—lord it over the beasts, divine right to run the place, and all that.
Now understand—it’s the animal who’s become intelligent, not the parasites.