When it comes to non-human characters, I always start thinking about biology. So, I decided to write a little about Duros evolution, biology, and culture (speculation and headcanons based on official canon and legend facts) and make an illustration in the spirit of the encyclopedias from my childhood.
On the left you can see the pristine, still green and covered with deep clean oceans planet Duro, as it was at the dawn of sentient life. The reptiloid, which could have been the ancestor of modern Duros, has the external features of a lizard and a frog, but is warm-blooded. It, like most of the fauna on this planet, has green blood based on ferrous oxide. This reptiloid is able to stand on its hind legs and quickly run short distances, has a fairly massive tail for balance. Its skin is tough but scaleless, and it sheds its skin like lizards. Its coloring provides good camouflage, and its large eyes, located on the sides of its head, provide a very wide field of vision. The muzzle is not elongated, since there is no nasal cavity. The vomeronasal organs, responsible for smell, are located under the eyes in the cavity of the cheekbones and open into the soft palate. Accordingly, these reptiles must stick out their tongue and then touch it to the palate if they want to sniff something carefully. The eyes have a full nictitating membrane, which allows them to be moistened, cleaned or protected while maintaining vision.
In my opinion, there are a number of signs indicating that the Duros ancestors were more prey than predators, and at the same time they themselves could have developed omnivory - this is the most advantageous strategy for survival. Small fangs, present in some individuals, do not contradict this at all - this can be seen in the example of Earth primates, even completely herbivorous ones. What you should pay attention to: large eyes with horizontal pupils (in the series, you can also notice that the eyes of the Neimoidians can even rotate so that the pupils remain parallel to the horizon). Such eyes are typical for animals for whom it is important to notice the approach of a predator in time. Another distinctive feature is a predominantly thin build and reduction of toes (there are certainly hints at this in the design of the Neimoidians) - this is typical for animals that have developed the ability to run fast. This, in turn, requires warm-bloodedness, the presence of a bird-type heart and huge lungs. I am sure that Duros have all of this, at least a hint of large lungs can be seen in the description of the physiology of Neimoidians, who have a very noticeable rapid breathing in a stressful situation (in addition, large lungs allow both species to speak and breathe without problems in the absence of a nose). Another sign is oily sweat, which, if an individual feels threatened, is secreted more abundantly and acquires a sharp, repulsive smell. This is a strategy clearly necessary for someone who could become prey. Its presence has become canon for Duros relatively recently, but initially something like this was mentioned for Neimoidians as well. The latter also react to stress or illness by turning their skin pale, up to pink, and I associate this with their ability to see in the infrared spectrum. This fact suggests that other members of the Duro fauna can also see thermal radiation, which would explain the reflex of draining blood from the skin when stressed or ill - this lowers the external body temperature and makes it easier to hide. I believe that the Duros also have this reflex, which originally arose in their ancestors, but the structure of their skin makes it less noticeable.
The next stage of evolution can be conditionally called Duros habilis; these reptiloids had a much more developed brain and had already mastered tools. Their binocular vision became clearer, and the structure of the pelvis changed to provide more perfect bipedality. Since childhood, I remembered the drawings of hypothetical reptiloids from books about dinosaurs, and now I believe that this is the evolutionary path that the Duro reptiles could have taken, so this evolutionary link has a non-random similarity with the dinosauroid. It may seem that it has less muscle mass, but this is actually a change in the ratio of muscle fibers, slightly reducing strength, but increasing endurance.
An upright individual, the closest ancestor of modern Duros, still has rudiments of claws and first and fourth toes, as well as a small tail. The appearance of claws in Duros and Neimoidians is an atavism, while the tail is present in larval stage and disappears during development due to autolysis (in my opinion, the grubs of both species resemble tadpoles adapted to a terrestrial lifestyle, that is, they initially have lungs and durable skin; while Duros have small limbs, the position of which changes as they turn into an adult, Neimoidians are born without limbs, only with a mobile muscular tail). This species could live in nomadic groups, mainly engaged in gathering and avoiding dangerous predatory fauna. Their brains increased significantly, since they needed good memory and orientation in space, they also made various, often multifunctional tools. The individual depicted here holds a spear, which could be used for defense or hunting small animals, as well as for cutting plants and harvesting fruit, or digging. The spear, like the breastplate of this so called Duros erectus, is made from fragments of the chitinous carapace of a giant beetle, and echoes of its use can still be seen thousands years later in the design of clothing (collars and pectorals) or weapons (Neimoidian vibro mace). The clothing of this upright Duros is made from the skin of some other reptile. Cloaks and capes also became traditional clothing early on, as it was important for a species to cover its back in order to avoid being wounded by predators.
The second image shows the planet Duro already damaged by industrialization; and here you can see a noble Duros from the early era of space expansion. The signs of his status are jewelry, especially rings (they were apparently a status symbol for the monarch, too, judging by the decorated hand of the lost king of Duro). While green was initially the most common skin color among Duros, in civilized society there was no vital need for protective coloring, and blue shades were increasingly no longer a rarity - perhaps, on the contrary, they began to be found more attractive due to their unusualness. Modern Duros differ from their closest ancestors in their smoother, longer face and, of course, in brain volume, as well as in the complete absence of a tail in adulthood. Otherwise, the body type remained slim and athletic (and traditional Duros dances are designed to demonstrate the agility and endurance that were so necessary for the survival of their ancestors - they are very energetic, include many jumps and other acrobatic elements). The modern species, apparently, retained the mentality of their ancestors - caution, avoidance of danger, easy-going and a tendency to escape from bad conditions. Therefore, most of them began to leave the polluted planet, and excellent memory, spatial thinking and the ability to quickly navigate and react, laid down genetically, made many Duros gifted navigators and pilots. Their people can also boast a large number of explorers and discoverers.
The colonization of various worlds by the Duros led to the emergence of new species, but so far we only know about one of them - the Neimoidians. And personally, it seems to me that their cultures are much closer than is commonly thought, and in general, the mutual hostility of the two species can be artificially reinforced by propaganda by those who benefit from it. Both Duros and Neimoidian people are enterprising, have business acumen and respect material success, considering the inability to maintain financial stability as a weakness (perhaps the very strict lending traditions of the Duros can be interpreted this way; also, both peoples nominal had a monarchy, when actual power belonged to influential corporations). I left a question mark where I still hope to see other branches of evolution in the future (of course, I can theorize that the Kyuzo and the Roonans also descended from the Duros, but it is not a fact that this will be confirmed).
It could be said that evolution in a galaxy far, far away happens at an unrealistically fast rate, in a time frame that is insufficient for mutations to accumulate and for speciation to occur. In this regard, the emergence of the Neimoidians is a surprisingly realistic story - if you look at their upbringing system, they are, in fact, the result of selection, deliberately organized intraspecific selection. Perhaps Neimoidia was an unsuccessful planet for terraforming, and its colonizers chose a strategy of changing themselves in order to survive. The external differences between the two species are not so expressive. Neimoidians look more robust due to thick bones and pronounced bony protuberances, which may be a consequence of the high gravity. Their large eyes provide better vision, necessary in the foggy atmosphere, and they have a slightly different shape of teeth (but not their number) - the enlargement of the molars is associated with a large amount of mushrooms in their diet. Also, I believe their lungs have become even more capacious, and the fact that their intense breathing under stress is noticeable despite the multi-layered clothing is explained by this, and not only by the fact that they breathe like lizards, using intercostal muscles rather than the diaphragm (the same muscles are used in both species when laughing, which is why their body shakes slightly when they laugh). I don't know about Neimoidia, but Cato Neimoidia should definitely have thin air, and in such conditions, lung capacity matters. The main difference between the two species, which allows us to consider them not just two races, is in reproduction and development. The system of intraspecific selection has also changed the mentality of the Neimoidians, for whom it is still important to avoid troubles, in that they prefer not to take risks searching for better living conditions, but to create them on the spot. Although their priority baceme a sedentary, stable and measured way of life, they inherit those qualities of their ancestors that make many of them quite outstanding captains of spaceships. Their people are more inclined to follow traditions and take pride in their culture, and also believe that they do not repeat the mistakes of the Duros in relation to their worlds. The noble Neimoidian depicted in the right against the background of his home planet has a belt with an image of a sacred beetle. In the formation of the Neimoidian civilization, as once for the civilization of the Duros, giant semi-sentient beetles play a significant role, performing important work in the sphere of food production (fefze may have served a similar role to harvester beetles before planetary pollution damaged their nervous systems).
In the upper right corner is a modern Duros in front of an orbital city, one of twenty located around his home planet, now almost uninhabitable. You can see that over the course of several thousand years, some changes have taken place - the head has become even larger, especially the braincase, and the face has become flatter. Blue coloration has continued to become widespread and acquire quite bright shades that could not originally appear in nature. In my opinion, the Duros, who have a wide variety of shades of blue, lilac and turquoise skin, are colored structurally, like Earth reptiles and birds, so some of them have skin color that may look different depending on the lighting. The Neimoidians, on the other hand, lack blue color completely, which can be easily explained by the different structure of their skin. Modern Duros are not too concerned with tradition and often dress practically, but jewelry in the form of rings remains quite popular.
