So most living things followed certain basic guidelines. That was probably because they all started in pretty much the same way, since there is a timetable to the development of life. The first step is just chemistry: inorganic chemicals get forced to react with each other, under the spur of some sort of externally supplied energy-usually the light from their nearby star. Then crude, single-celled little things appear. These are only factories whose raw materials are the other inorganic chemicals in the soup that surrounds them. They, too, use the energy of sunlight (or whatever) to process the inorganic chemicals into more of themselves, and that's about all they do for a living. Since they are photosynthetic, you might call them plants.
Then these primitive "plants" themselves turn out to be pretty rich sources of assimilable chemicals. Since they've gone to the trouble of concentrating the more appetizing inorganic compounds into a preprocessed form, it is only a question of time until some of them learn a new diet. These new ones don't eat the raw materials of the environment. They eat their own weaker, more primitive cousins. Call this new batch of creatures "animals." The first animals aren't usually much. They consist of a mouth at one end, an anus at the other, and some sort of processing system in between. That's all they are. But then, that's all they need to be to feast on their neighbors.
Then things get more complicated.
Evolution begins to happen. The fittest survive, pretty much the way Charles Darwin figured it out as he fondled his captive finches on board the Beagle. The plants go on making appetizing chemicals for the animals to feast on, and the animals go on feasting on the plants and on each other-but some plants accidentally develop traits that give their predators trouble, and so those plants survive; and some animals learn tricks to get around those defenses. Later generations of animals develop senses to locate their prey more
efficiently, and musculatures to catch it, and ultimately complex behavioral systems (like the web of a spider or the stalking of a great cat) that make their predation more and more successful. (Then, of course, the plants, or the herbivores, or the less successful predators begin to develop defense mechanisms of their own: the poisons in a shrub's leaf, the quills of a porcupine, the fleet legs of a gazelle.) The competition never stops getting more intense, and more sophisticated on all parts-until, finally, some of the creatures become "intelligent." But they take a lot longer to evolve . . . and it took the Gateway prospectors a lot longer to find any of them, too.
In the myriad worlds that the Heechee had explored-and to which the human Gateway prospectors followed them hundreds of thousands of years later-all those basics of the evolution of life were played out a thousand times, with a thousand variations. The variations were sometimes quite surprising. For instance, Earthly plants have one conspicuous trait in common: they don't move. But there wasn't any reason why that trait had to be universal, and in fact it wasn't. The Gateway prospectors foux~d bushes that rolled from place to place, setting roots down to one side and pulling them up on the other, like slow-motion tumble-weeds as they sought the richest soils and the best access to groundwater and the surest sunlight. Then, too, Earthly animals don't normally bother with photosynthesis. But in the seas of other worlds there were things like jellyfish that floated to the surface by day to generate their own hydrocarbons from the sun and the air, and then sank down to feast on algal things at night. Earthly corals stay in one place. Prospectors found some unearthly ones-or, at least, some unearthly things that looked more or less like corals-that flew apart into their component little animals when the coast was clear, to eat and mate, and then returned to form collective rockhard fortresses when the prowling marine predators approached.
Most of these things were useless to any prospector whose big interest was in making a fortune. A few were not. There was one
good feature to finding an organism that was worth something, and that was that it was an easy import. You didn't have to bring tons of material back to Gateway. All you had to do was bring enough of some plant or animal back to breed others back on Earth, since living things were glad to reproduce themselves for you anywhere.
The zoos of Earth began to expand, and so did Earth's aquaria, and its pet stores. Every fashionable family was sure to own its exotic windowbox of alien ferns, or its furry little pet from the planet of some other star.
