Communication also is key, which can occur through sound (link to: humans, zenats), telepathy (link to: naurons) or physical gestures and coloration (link to: xyn). The Marquad Family was not denying that there are millions of intelligent species in the galaxy. But those emerging with the ability to ask "why", become self aware, and seek out new opportunities with technology require these very specific biological traits. Of course, culturally, the four known sentient species are very different. One of the most telling diffences is food preference. All sentients are omnivores, capable of eating varied diets of plant and animal matter. However, how food is perceived and valued is species specific. Humans have the most varied diets, typically preferring a mix of plant and animal matter in their meals. Obesity is common because food can be considered a psychological as well as physical source of nutrition. When naurons first came into contact with humans, food preference was a topic of much discussion. Narons, being semi-aquatic, prefer to consume marine food, largely of planktonic origin. Their meals are typically uniform. Lacking taste buds, they still puzzle over humanity's need for varied meals.
