Walter Jon Willams, "Dinosaurs", 1987
Millions of years in the future, humanity has evolved and engineered itself along specialized branches. One such human, a diplomat named Drill, travels to an alien world to attempt to negotiate a peace treaty with the local civilization. Drill has a secondary brain that voices its physical urges to his primary brain.
Drill's spacecraft carries human-derived lifeforms of much lower intelligence than himself — non-sapient, although they can respond to voice commands — to provide for his physical and emotional needs. One is a reclining slab bed; Drill is much larger than a human of our time, and he has difficulty lying down and standing up on his own. Another is a sexual companion featuring multiple male and female reproductive organs.
The three-legged aliens have more in common with 20th-Century human behaviour, culture, and technology than the evolved humans do, and are in danger of being obliterated without malice as humans terraform and colonize their territory.
Drill's mission is initially a success. He provides the aliens with a portable biological memory module that they can carry with them to encounters with other humans. In this way, the other humans can verify the treaty that the aliens first made with Drill. Unfortunately, the progress is all for nothing when word arrives from space that the aliens' fleet has attacked human ships. Drill informs the aliens that this attack will prompt the human warrior subspecies to respond with genocidal force that no amount of diplomacy can stop.
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