Charles Sheffield - Tomorrow and Tomorrow

Milton paused, and Drake laughed.

“Don’t worry about hurting my feelings. I’ve been wrong more often than you can imagine.”

“But right more often than any other being in the Galaxy. Let me continue. The Shiva are living organisms, unlike any encountered before. They have four distinct phases to their life cycle. Two of those phases are capable of two different forms of reproduction. The first phase, which we will call the adult Shiva, is immobile and enormous — one full-grown specimen can measure two hundred kilometers across its base, and stretches high enough for its top to extend beyond the atmosphere of most planets. The adult is invulnerable to normal predator attack, because of its size, and also because it is protected by a second form. We will call this second form the warrior, although it acts aggressively only in defense of the adult. The warriors are one form of offspring of the adults.

“It is important to note that the adult, in spite of its size, can survive only in certain environments. Atmospheric oxygen and water vapor must lie within tight limits. Most worlds of the Galaxy do not come close to satisfying that requirement. We will come back to this question later.

“And one other point, perhaps an obvious one: an adult, because of its size, grows, lives, and dies on a single planet. No Shiva adult can ever travel to another world.

“But when they achieve full size, the adults can send another form of offspring out into space. There is a mystery here — the propagation mechanism is not something as simple as dehiscence, an explosive projection of seeds. However, let us use the analogy and call this phase a Shiva seed. The seed is tiny and light, nothing like the warrior, and once in space its movement is assisted by two factors: radiation pressure, pushing it away from the planet’s primary, and the galactic magnetic field. Originally, the seeds may have propagated only to other parts of the home world; but billions of years ago they became an interplanetary and an interstellar traveler; eventually, an intergalactic one. We do not know where the Shiva originated, but it was not in our galaxy.

“The Shiva seed is enormously tough and durable, able to survive extreme environments and a multimillion-year passage through space. There is another mystery which still waits an explanation: the seed motion is not mere random drift. Movement is preferentially toward other stellar systems. In the final stages, that implies movement against radiation pressure.

“Most Shiva seeds must end their lives on barren planets, or burn up as they fall into stars; but there are enormous numbers of them. Some small fraction will meet a world and drift down through the atmosphere to a surface on which they can transform to the next stage of the life cycle.

“This stage we will call the worker, though analogy with Earth’s social insects must not be carried too far. It would be just as good to call it a changer or a preparer. The worker, like the adult, is a sessile form incapable of movement. It is the plantlike entity that we saw long ago on Lukoris. Like the seeds, it is tough and robust. Workers thrive on worlds that would quickly kill an adult. They also propagate like plants, and they do so very fast.

“We have debated whether the worker or the adult should be considered the mature form of the Shiva, and decided that the question is meaningless. As in cryptogams, the ferns of Earth, two forms are alternating mature phases of a complex life cycle.

“Much more important, from the human point of view, is the worker’s other function. It is able, through a combination of generated fields and chemical diffusion, to affect the behavior of native animals on a planet. You have argued that only intelligent beings could be affected by the Shiva, since they alone are able to consider an alternate reality. It was then natural to conclude that the worker form of the Shiva must be intelligent.

“We now believe that those deductions are false. In our own galaxy, before the spread of humans, life developed on a billion worlds. Only five of that great multitude of forms achieved self-awareness. A life-form that relied on the presence of intelligence on every planet that it reached would surely fail. Moreover, the worker is not itself intelligent, and thus can have no concept of intelligence. Unable to move, it must somehow achieve its objective while remaining in one place. The objective is simple: the planet must be changed from its initial state to one in which an adult Shiva can thrive. Then, and only then, will the worker advance to its second form of breeding and produce not more workers, but new adults. Those will in turn grow, mature, and allow the Shiva to reach new worlds.

“The workers employ the native life-forms on a world as the unwitting agents for planetary change. Their breeding, their numbers, and their patterns of behavior alter under the workers’ control, to make the world suitable for adult Shiva habitation. Some native species will become extinct. Some will thrive, some will evolve to other forms. When the planet is ready, the adults begin their growth. The workers disappear. The life cycle begins again.”

Milton fell silent. The wiry head began to writhe more furiously than ever.

“That’s wonderful.” Drake wondered what was not being said. “Once you understand something, it’s much easier to stop it. The Shiva are vulnerable. We can destroy their seeds as they reach a planet, or kill the workers as soon as the plants appear. If I hear you right, humans don’t suffer their changed perception of reality until the workers begin to operate.”

“That is correct.”

“So let’s get going. There’s plenty of work to do.”

Milton sat silent, and at last Tom Lambert said, “A ton of work. But there are a few more things that we have to talk about. First, we’ve been thinking all the time of the Shiva as evil — as deliberate, calculating destroyers. That just isn’t true. There was no malice involved, no plan to achieve destruction. Changing human perceptions, even making the colonies use the defenses that we installed against us, was an accident. We believe that the adult, form of the Shiva possesses some kind of intelligence and self-awareness, but the workers do not. They were simply doing what all life-forms do, trying to ensure their own survival and propagation. In the case of humans, Shiva propagation required the acceptance of a false reality that justified human actions.”

“And, sooner or later, led to the human’s death.”

“True. But now that we know what’s going on, we may find many ways to stop the Shiva. Peaceful ways. There will be no more wholesale destruction of our planets or theirs; no more firebreaks, devastating whole arcs of the Galaxy; no more use of the caesuras, casting ships and intelligences and worlds beyond the bounds of space and time. And there will be no need for certain other things.”

And Drake, at last, saw what they were unwilling to tell him directly. “You mean, there will be no more need for me.”

“Yes. The service that you have performed for us is too great ever to be measured. We are eternally in your debt. When we thought that the Shiva were malicious and deliberately trying to destroy us, your presence and courage and mode of thinking were absolutely essential. Now, they are not. Of course, we would not suggest that you, or we, do anything at once. Many, many unknowns and potential difficulties remain. We hope that you will assist in their solution. But ultimately we see you as a hindrance to peaceful answers. You are too steeped in war, too much in favor

of the crudities of combat.” Tom Lambert ducked his head. “I’m sorry, Drake.”