As part of my preparation for writing the science fiction story I’ll probably never get around to starting, I’ve been thinking of what types of behavior can we expect creatures on an alien world to exhibit.

The best way I can think of going about this is to consider behavior that has evolved in the creatures of our own planet, not necessarily unusual or unique behavior, but those actions which seem to be shared by many distantly related terrestrial life forms, and not just lucky accidents that have proven to be evolutionarily successful and been passed on to subsequent generations.

Behaviors that appear over and over in the animal kingdom are probably natural responses to environmental conditions. If they have arisen independently here in a variety of species it suggests these are fundamental responses to the surroundings and it is reasonable to assume the beasts of another world will also have evolved them.

For example, many animals are territorial. They drive off members of their own kind from areas they have staked out to insure access to food, mates, and other resources. This ensures that niches do not become over-populated and provides a pressure for competitors to travel to other, unocccupied areas. This helps to propagate the species without exhausting the animals’ range. Those who are too weak to challenge this territorial agression will either find additional resources elsewhere, or will, by definition, be surplus population that should not be competing for resources with their own kind. Those strong enough to meet that challenge have shown themselves more capable of exploitng the territory, and (evolutionarily, at least) more beneficial to the species as a whole by being able to drive the resident off.

Other creatures find it effective to flock or herd together, increasing survivability by the strength of numbers. This does not necessarily mean they cooperate in fighting off predators, very often it just means the slowest or weakest in the flock is taken by the hunter, while he pauses to feed the others escape. If you have to lose someone, it is genetically smarter to lose the weakest, slowest, dumbest, youngest. It also decreases a lone predator’s probability of finding prey, which means less predation overall. Besides, many pairs of eyes on the lookout are better than one.

Social animals have also evolved elaborate pecking orders and hierarchies, and an entire suite of behaviors to support them.. These behaviors also tend to be remarkably similar across species boundaries. Many unrelated animals also exhibit courtship behavior which is uncannily similar. Aggression and timidity often can be turned on and off, depending on the season and the stage in the life cycle of the creature. Many plants also display these types of behaviors, although in less obvious ways. Some behavioral pattterns, on the other hand, such as those of social insects, seem to have originated only a few times, and are now only taxonomically widespread because the originating genotype has since evolved into a variety of forms sharing a common ancestor.

These are common actions shared in many distantly related species, and they often evolve anatomical and physiological tools to assist their behavioral imperative, such as ritual threat displays, marking of territory, schooling instincts, symbolic combat, mating plumage and so forth. No doubt there are many more I have not identified. Can you guys think of any others?