Heaven by Ian Stewart

system, up into the midbrain, and then . . .
    Second-Best Sailor
, said a faint voice.
Remember this message with care, for it can be told only once
. Second-Best Sailor had no idea how this magic worked—it actually involved tailored neurotoxin chains that caused sequential
     inflammatory reactions in parts of his sensorium. A molecular message system, a kind of long-distance chemical telepathy.
    There followed a complicated series of instructions, but their general gist was simple. “We suspect Cosmic Unity to be a malignant
     benevolent memeplex. We are making contingency plans in case we are right. Select a few nines of fellow mariners, and persuade
     the ’Thals to convey them offplanet immediately and evacuate them to a suitable
safe
home for an indefinite period. Reveal our existence to them. Repeat:
Tell them that the reefmind exists
. The ingrained social prohibition is lifted, but only as far as this group of Neanderthals is concerned. The danger is great,
     and concealment would now be counterproductive. Send an encryption disk to our males at Atollside Port that will link them—and,
     at one remove, us—to the ’Thal ship’s ansible. We will then handle the task of convincing the ’Thals that a coral reef can
     house a conscious mind. That will be easy, for our intelligence cannot possibly be attributed to you males. Tell the ’Thals
     to confirm their choice for the evacuation world with us. As payment, offer them free simulations for life; do
not
delay action by attempting to bargain.”
    The prohibition on bargaining went even more against the grain than the instruction to reveal the secret of the reefmind to
     offworlders, but Second-Best Sailor had long ago learned the hard way that the wishes of the reefwives were not to be denied.
     He wondered what could possibly have caused such a panic. The sun about to go nova? A comet strike? With a heartfelt flush
     of his siphons, he headed for his cabin, to put the suit back on.
    It was a lot to ask. He hoped the Neanderthals would agree. But he never doubted for an instant that the reefmind would persuade
     the ’Thals of its own existence. Second-Best Sailor knew from personal experience exactly what his mother was capable of.
    The Neanderthal ship didn’t really have a commanding officer—it pretty much took the decisions itself. As far as the crew
     were concerned, Sharp Wit Will Cut behaved as a leader, but the ship took its own counsel and seemed generally to respond
     to the overall consensus. In fact, experience with Precursor starships showed that the more diverse a population the crew
     members were, the better the ship seemed to function, and the easier it was to control.
    This particular vessel had been part of a fleet found drifting in the vicinity of Iota Ursae Majoris by a band of magnetotorus
     herders, and it had taken part in the original Neanderthal evacuation from Earth, forty thousand years ago. Its official name
     was
Talitha
, the name that ancient Arabic astronomers had given to the star where it was found, but the Neanderthals called it “Ship.”
Talitha
was a generation ship: Its crew lived the main part of their lives on board, and their families traveled with them. And most
     of the time it traveled at just below the speed of light. However, unlike a true generation ship, it also possessed a Precursor
     faster-than-light hydrive. But the hydrive consumed large amounts of energy and so could be used only when it was really necessary.
    Despite its gigantic size, the ship was a village, not a city, housing some six hundred crew, along with their families—maybe
     fifteen hundred altogether. Of the half dozen or so species on board, the majority were Neanderthals, Tweel engineers, and
     Cyldarian ecologists. A lot of the space on the ship was taken up by life-support systems for their varied environments—oxygen,
     nitrous oxide, chlorine, and so on. Cargo holds occupied much of the rest. Even so, the ship could have housed a