When she spoke again, her voice was lower, slower and steadier. The gravelly quality was muted somehow, and she seemed suddenly very serious. "We have been speaking of this as an ecological infestation, because we can't prove that it's anything more. We have specifically not called this an invasion, because we have not been able to find an invading force. We have no evidence of extraterrestrial landings, no sightings of ships, no evidence of advanced technology of any kind. If we are being invaded, then where are the invaders?
"For a while, we suspected that the large purple and red creatures that we have been calling Chtorrans were our alien visitors, but this theory is rapidly falling into disrepute, because we have not been able to prove that these creatures even have the potential for intelligence-let alone the capabilities necessary to mount such an invasion across the vast distances of space. We are assuming, of course, that this ecological infestation has as its source a planet in another star system-it could not possibly have originated on any of the planets in our own solar system. I refer you to Dr. Swale's analysis for the reasons why we have come to that position. So the question remains: where are the invaders?
"I'm actually going to answer that-in a way. But it's a circuitous route. You'll have to bear with me a bit, because in order to find out who the culprit is, we have to take a good long look at the evidence.
"When we look at the overall pattern-the stingflies, the nightwalkers, the red kudzu, the sea sludge, the bacteria that caused the plagues, even the, ah, Chtorrans themselves-we find that there is a pronounced tendency toward voraciousness, as if all of these life forms have evolved in a much more competitive ecology, not only surviving, but succeeding in that environment. Here on Earth, without their natural predators-all the checks and balances of a stable ecology-these life forms cannot help but run wild. We're seeing it happen all over the planet.
"We expect to find that none of these creatures are harmless to the Terran ecology-especially not the ones that look harmless. They're the ones that represent the biggest danger, because they're the ones we're most likely to underestimate. We have one hundred and fifty-four new species identified, and there are probably a lot more that we haven't yet discovered. And that's because we don't have the people. For all practical purposes, most of the world's ecological maintenance agencies have ceased to exist. And that leaves us particularly vulnerable to this kind of ecological infestation-twice over. Once because we don't know all of what's happening out there, and twice because even where we do have monitors in the field, we do not have the resources to respond. We need to rebuild those agencies-without delay! If we mobilize now, there is still the chance that we can create a strong response to the threat. If not, then the pressure on our ecology of those hundred and fifty-four various and voracious new species will surely shatter what remains of life as we know it on this planet.
"It is this simple: our ecology is under attack by a far more successful ecology. The home planet may be half a billion-I said billion-years older than the Earth-with all the corresponding advantages of extended evolution that implies for the member species of that planet's ecology. The implied age of the ecology and its host planet may also be a clue to why this infestation is occurring at all. The host planet may be wearing out. Or its sun may be going cold. What we are seeing may very well be an attempt by an intelligent species to-outlive the death of its home system.
"And-if we are correct about the age of the Chtorran ecology, that is also why we will not be able to use terrestrial microorganisms against the Chtorran life forms. If the Chtorran life forms that we have seen are the products of an extra umpteen million years of evolution, then that implies that they would also have the cumulative immunities against every mutation of every germ that has evolved on their home planet. And that suggests that they would therefore have a greater spectrum of resistance to unknown microorganisms. Our germs are going to be no threat to them, because to them, our ecology is simpler-much simpler. We are the great reptiles looking at the appearance of grass and blossoming flowers and therapsids in our ecology and wondering what the hell is happening to our world. We have no natural defenses here."
She leaned out across the podium as if to look into the face of every one of us in that auditorium. "If we accept this hypothesis -and I do not see how we can avoid it-then the motive of the initiating agency is no longer in question. There is only one possible interpretation of the situation: we are at war! A war unlike anything ever experienced or even conceived in the history of this planet!" She stopped herself, as if she were embarrassed at her own intensity. She covered it with a drink of water, just a sip, then continued. "The problem is that we have no evidence of the agency behind this invasion. It has to be there, but where is it? Again we come back to the question: where are the real Chtorrans?" Dr. Zymph let the question hang there in the air for a moment. She looked over her notes and rubbed the bridge of her thick nose between thumb and forefinger.
She looked up again, and when she spoke, it was like a burst of gunfire. "Actually, we might be asking the wrong question. We have to look at the situation from an invader's point of view. I refer you now to the Skotak-Alderson studies on how to colonize a planet. In those papers, of course, the authors were talking about Venus and Mars, but the general principles they laid down are extensible to any world.
"Briefly, Skotak and Alderson broke the colonization process down into sections. Part I is Terraforming and Phase I involves producing an atmosphere that Terran organisms can survive in. Phase II begins with the introduction of selected life forms to create a favorable protoecology on the world to be colonized.
"Now, applying that to our own situation, obviously some intelligence somewhere is working its own Phase II here on Earth. They are Chtorraforming the planet, if you will.
"Just as we would need to establish grasslands to feed our cattle, cornfields to feed our chickens, forests to provide our paper and lumber and plastics, bees to pollinate the blossoms of our plants so we can have fruits and vegetables, so must our unknown Chtorran planners need to establish the equivalent support species necessary to the survival of their civilization. That is precisely what is happening now. And will continue to happen.
"Based on a weighted Skotak-Alderson simulation, the infestation of the Earth will occur in three, perhaps four, distinct stages. Each stage will see a specific level of species support established before the next level appears. In other words, they won't bring in the Chtorran equivalent of coyotes until the Chtorran rabbits are fat, and they won't bring in the Chtorran rabbits until the Chtorran pastures are green--0r in this case, purple-and they won't plant the pastures until the Chtorran earthworms have softened the ground. That puts us at a disadvantage, because we'll be seeing each species out of context, not knowing where each one fits in the larger pattern. It'll be as difficult as trying to extrapolate the rest of the symphony, when all you have is the sheet music for the tympanist and the third trombone.
"That's why we can't give you the hard answers yet. What facts we do have are still unconnected. We can only give you the larger pattern that all the facts point to. This infestation of the Earth is their way of clearing the land. It's the easiest way to deal with the local residents-clear them out before you move in. We're supposed to be long gone before the new tenants arrive. If you'll pardon an unpleasant metaphor, what we are experiencing is the Chtorran version of a slum clearance. A neighborhood improvement project-"