Free Footsteps in the Sky by Greg Keyes

the head, a fourth pair of limbs emerged, triple jointed, and terminating in seven-digit monstrosities that looked horribly like human hands.
    â€œTell me about this thing,” he said, quietly.
    Kewa’s voice emerged, ghostly and unseen.
    â€œThere’s a lot we don’t know. It breathed oxygen, after a fashion, both through small nostrils above the mouth and through that funnel in its head. We think the funnel evolved from a sort of supercharger, designed to ingest atmospheric alcohol and create positive pressure in its circulatory system. The heart is a long, tubular muscle underneath the spine. It acted like a sort of linear accelerator, contracting in waves and forcing blood from one end to the other. It doesn’t have lungs, as such; air was passed through successively smaller networks of vesicles and then injected into the heart.”
    The cube showed him the dissected corpse, the long yellow muscle she was referring to.
    â€œThe heart was protected by a bony cylinder lying just above it, and we think this housed the brain. It’s more like a very thick spinal cord, and there are various sense organs attached along it, though we aren’t sure what they all do. The strange thing is that there was much more empty space in the casing than nerve material. That doesn’t appear to be natural, but we can’t explain it. Our guess is that this individual had an atypically small brain, but that doesn’t make much sense.”
    Hoku smirked sardonically. “That’s because you aren’t a politician. They obviously sent this thing down to see if the atmosphere was tenable. They sacrificed it. Would you volunteer for such a mission if in possession of all of your faculties?”
    â€œMother-Father, there is no evidence of surgery,” Kewa replied.
    â€œAssuming you know what surgery would look like in such a beast. But perhaps you are right—perhaps it was grown or raised with only a minimal brain.”
    There was a pause, and then Kewa stammered: “Th-that’s horrible.”
    Hoku shrugged. “Judge them if you wish. It is not my concern. What I want to know is this: how intelligent would a fully functioning alien be?”
    Kewa answered quickly, with a hint of indignation. “Impossible to tell. We don’t even know how its “neurons”—if that’s what they are—functioned. No, I could not hazard even a guess.”
    â€œWhy are its limbs arranged so?” he asked, avoiding frustration by changing the topic.
    â€œThe backbone is its central functional support. We believe that this creature evolved from animals with simple linear symmetry. The appearance that it is bilateral in nature—like we are—is illusory. Each pair of limbs emerges from the backbone, one behind the other. Only their peculiar articulation allows them to function perpendicular to the creature’s axis.”
    â€œYou’re saying that its ancestors would have had eight limbs arranged one behind the other.”
    â€œYes. Much like the worms indigenous to this planet. The two are clearly related.”
    â€œThis creature could have lived on this planet as our ancestors found it.”
    â€œUndoubtedly,” Kewa affirmed, for once very sure of herself.
    Hoku tapped his cup again. He had, of course, suspected that for fifteen years, but the Tech Society had known for sure all along. Clearly, they were due a come-uppance. But not now, not now.
    All of his assumptions had just been validated. The original masters of the planet had certainly come back to claim it. And yet, they had an odd sense of propriety. For twenty Standard Terran Years they had rested in their high orbits, uncommunicative and apparently inactive. Until now, at least.
    â€œKewa,” he said. “Copy this to my personal files, please.”
    The monster dissolved and was replaced by Kewa’s frowning features. “Mother-Father,” she began, “that is