They are an ecology, in other words. These manifestations either play some explicit role in that process or are an unintended consequence of it. I don't believe they represent any kind of deliberate strategy on the part of a higher consciousness."

"Yes," Mrs. Rebka said impatiently, "but if your people understood enough to engineer Hypothetical technology into human beings—"

"You possess that ability too." Sulean Moi looked pointedly at Isaac.

"Because it was given to us by Wun Ngo Wen."

"Our work on Mars has always been purely pragmatic. We were able to culture samples from the ashfall and observe their ability to interact with human protein at the cellular level. Centuries of that kind of observation produced some insight into the ways human biology might be manipulated."

"But you engineered what you admit is Hypothetical technology."

"Technology or biology—in this case I'm not sure the distinction is meaningful. Yes, we cultured alien life, or technology if you prefer that word, at the microscopic level. Because it grows, reproduces, and dies, we were able to select and manipulate certain strains for certain traits. Over the course of a great many years we generated the modified cultures that enhance human longevity. And other germ lines as well.

One of the most radical of which is the treatment you applied to Isaac while he was still in the womb. In your womb, Mrs. Rebka."

Mrs. Rebka reddened.

Turk understood the significance of what they were discussing, and he guessed it was important, but it seemed ridiculously remote at a time when real problems were percolating so close to hand. Right outside the door, in fact. Was it safe to go outside? That was the question they ought to be asking.

Because sooner or later they would have to leave this room. Because they had very little in the way of food.

He begged the loan of Dr. Dvali's little radio and pushed the nodes into his ears, blocking out the querulous Fourths and inducing other voices.

The available broadcast was a narrowband thing from Port Magellan, two guys from one of the local media collectives reading UN advisories and updated reports. This ashfall had been only a little worse than the first, at least in terms of weight and duration. A few roofs had collapsed to the south of the city.

Most roads were currently impassable. People with respiratory problems had been sickened by ash inhalation, and even healthy people were spitting gray residue, but that wasn't what had everybody scared. What had everybody scared were the peculiar things growing out of the ash. The announcers called these things "growths" and reported that they had appeared randomly across the city, but especially where the ash was deep or had drifted. They sprang from the dust, in other words, like seedlings from mulch. Although they lived only briefly and were quickly "reabsorbed" into the local environment, a few of them—"objects resembling trees or enormous mushrooms"—had erupted to impressive heights.