The On light glowed yellow. Evalyth tugged her chin, searching for words. “The objective,” she said at length, “is to trace a lowlander who has consumed several kilos of flesh and blood from one of this party, and afterward vanished into the jungle. The killing took place about sixty hours ago. How can he be found?”

The least hum answered her. She imagined the links; to the maser in the ferry, up past the sky to the nearest orbiting relay unit, to the next, to the next around the bloated belly of the planet, by ogre sun and inhuman stars, until the pulses reached the mother ship; then down to an unliving brain that routed the question to the appropriate data bank; then to the scanners, whose resonating energies flew from molecule to distorted molecule, identifying more bits of information than it made sense to number, data garnered from hundreds or thousands of entire worlds, data preserved through the wreck of Empire and the dark ages that followed, data going back to an Old Earth that perhaps no longer existed. She shied from the thought and wished herself back on dear, stern Kraken. We will go there, she promised Donli’s child. You will dwell apart from these too many machines and grow up as the gods meant you should.

“Query,” said the artificial voice. “Of what origin was the victim of this assault?”

Evalyth must wet her lips before she could reply: “Atheian. He was Donli Sairn, your master.”

“In the event, the possibility of tracking the desired local inhabitant may exist. The odds will now be computed. In the interim, do you wish to know the basis of the possibility?”

“Y-yes.”

“Native Atheian biochemistry developed in a manner quite parallel to Earth’s,” said the voice, “and the early colonists had no difficulty in introducing terrestrial species. Thus they enjoyed a friendly environment, where population soon grew sufficiently large to obviate the danger of racial change through mutation and/or genetic drift. In addition, no selection pressure tended to force change. Hence the modern Atheian human is little different from his ancestors of Earth, on which account his physiology and bio-chemistry are known in detail.

“This has been essentially the case on most colonized planets for which records are available. Where different breeds of men have arisen, it has generally been because the original settlers were highly selected groups. Randomness, and evolutionary adaptation to new conditions, have seldom produced radical changes in biotype. For example, the robustness of the average Krakener is a response to comparatively high gravity; his size aids him in resisting cold, his fair complexion is helpful beneath a sun poor in ultraviolet. But his ancestors, were people who already had the natural endowments for such a world. His deviations from their norm are not extreme. They do not preclude his living on more Earth-like planets or interbreeding with the inhabitants of these.

“Occasionally, however, larger variations have occurred. They appear to be due to a small original population or to unterrestroid conditions or both. The population may have been small because the planet could not support more, or have become small as the result of hostile action when the Empire fell. In the former case, genetic accidents had a chance to be significant; in the latter, radiation produced a high rate of mutant births among survivors. The variations are less apt to be in gross anatomy than in subtle endocrine and enzymatic qualities, which affect the physiology and psychology. Well known cases include the reaction of the Gwydiona to nicotine and certain indoles, and the requirement of the Ifrians for trace amounts of lead. Sometimes the inhabitants of two planets are actually intersterile because of their differences.