Excerpt from “Universal Guide to Galactic Etiquette, with Practical Hints for Every Social Occasion” by Sensei Eureka Starlight.
Good posture is extremely important. More important than most gentle-folk realize. One should always try to appear healthy and vigorous. Correct posture is a crucial part of this. When your posture is correct for your species you are able to present yourself in a confident, dignified, and lively manner. This is crucial for a variety of reasons.
Let’s begin by considering animals. No animal wants to display weakness or ill health as that would make them a target for any nearby predators. Anything that would signal good health, vigor, a high energy level, and mental alertness would discourage predators and attract possible reproductive partners. So animals always try to present themselves to the best advantage.
Animals are not the only predators in the universe. It is unfortunate, but some people do belong to the criminal class. Like animal predators, the criminal class preys on the weak. Criminals are basically lazy. They would prefer not to exert themselves. They search other gentle-folk for signs of weakness, inattention, and ignorance. A person who presents themselves as healthy and alert, willing and able to put up a fight, is not someone a criminal would want to choose to victimize.
Everyone wants a reproductive partner that is considered beautiful by the standards of their species. Common signals of beauty are health, vigor, mental liveliness, symmetry, good coloration, and luxurious fur/hide/skin/scales/porous membrane. Good posture is a signal, or presentation, of many of these signals.
Now take a moment to consider the gentle-folk around you (or if you are alone, other gentle-folk of your acquaintance). There are many signals of health and vigor that are beyond people’s ordinary control, such as symmetry, though marvels can be done with elective surgery. However posture is controllable by most gentle-folk. A well-rounded Gortabulan floating purposefully through the clear, green, buffered oceans of Sublastis 6; a gently arched U-wyrri undulating swiftly through the grassy corridors of the Galactic Alliance Capitol Station; a tall, erect Terran standing steadfast guard by the entrance to a creche; each of these is a glorious sight. Such people are respected and admired. Thus should all gentle-folk be.
Cultivate and practice good posture. It will serve you well in your travels through the galaxy and as you live your exuberant life.