
Twenty-five million years before the present time, a race of nonviolent,
eight-foot-tall giants had flourished across the Solar System and surpassed
everything that humankind had achieved. The "Ganymeans"—so-called when the
first indication of their existence was discovered in the form of a wrecked
spacecraft buried under the ice of Ganymede, largest of the Jovian moons—had
originated on a planet christened Minerva, that had once occupied the position
between Mars and Jupiter. By the time the Ganymean civilization reached an
advanced stage, climatic conditions on Minerva were deteriorating. As would be
expected, their voyages of discovery had brought them to Earth, from where
they transported large numbers of plant and animal forms from the late
Oligocene–early Miocene period back to their own world as part of a
large-scale bioengineering research project to combat the problem. Terran life
enjoyed a generally greater toxic resistance than that possessed by the
Ganymeans, and their hope was to incorporate the appropriate genetic
structures into their own makeup in order to render themselves tolerant to
altering Minerva's atmosphere in a way that would enhance its natural
greenhouse mechanism. These efforts failed, however, and the Ganymeans
migrated to what would later come to be called the Giants' Star, located
twenty light-years from Earth in the direction of the constellation of Taurus.
In the millions of years that followed, the imported terrestrial animals left
on Minerva replaced most of the native Minervan forms, which owing to a
peculiarity of early Minervan biology that precluded the emergence of
land-dwelling carnivores, were unable to compete effectively. The terrestrial
forms included a population of primates as advanced as anything existing on
Earth at the time, which in addition had undergone genetic modification in the
course of the Ganymean experimental program. Fifty thousand years before the
present time, while the various hominid lines developing on Earth were still
at stone-using stages of culture, a second advanced, spacegoing race had
already appeared on Minerva as the first version of modern Man. They were
given the name "Lunarians," after evidence of their existence came to light in
the course of twenty-first century lunar exploration. (See Inherit the Stars.)
At the time of the emergence of the Lunarians, varying solar conditions were
bringing the onset of the most recent ice age on Earth, while the even greater
effect on Minerva threatened to render the planet uninhabitable. The Lunarians
responded with a concerted effort to develop their space and industrial
technologies to a level that would permit mass migration to the more
hospitable climate of Earth. But, as with the Ganymeans before them, the
ambitious plan came to nothing. When the Lunarians were practically within
reach of their goal, the cooperative spirit in which they had worked for
generations broke down with the polarization of their civilization into two
superpowers, Cerios and Lambia. Resources that could have been concentrated on
saving the race were squandered instead on a ruinous military rivalry. The
result was a cataclysmic planetwide war, in the course of which Minerva was
destroyed.
The Ganymean culture, in the meantime, had entered a long period of stagnation
brought about by the unanticipated effects of advancing biological science to
the point of prolonging life practically indefinitely. When the consequences
became clear, they took a decision to revert to their natural condition and
accept mortality as the price of experiencing a life enriched by motivation
and change. By the time of the events on Minerva, they had established a
thriving interstellar civilization centered on the planet Thurien of the
Giants' Star system. The Thuriens were never comfortable with what they
regarded their ancestors' abandonment of a genetically mutated sapient species
left to take its chances in the survival arena of Minerva, and followed the
subsequent emergence of the Lunarians with a mixture of guilt and increasing
awe. But when it all ended in catastrophe, the Thuriens relaxed the policy of