Physical Description

It's really hard for me to put into words what the yinrih are supposed to look like. A lot of this project has been about their ergonomics, and I have to know what their body is shaped like as well as the range of motion of their limbs, how good their gross and fine motor skills are, etc. in order to be able to come up with their tools.

Their head is essentially canine, with a wet nose, mesocephalic muzzle, and erect ears. Their ears are more motile than a dog's. They can tilt them forward such that the tips of the ears are pointed toward the direction they're looking. Their eyes are completely different than any terrestrial animal. They have normal-looking eyelids, but rather than eyeballs attached to ocular muscles they have patches made up of organic nanoantennas that couple with ambient EM radiation similar to a radio. These patches absorb almost all incoming light, making it appear as though a yinrih's eyes are coated in vantablack. It looks disturbingly like they have black holes where their eyes should be. Underneath their normal eyelids are a series of bandpass filter membranes that, to a human, look like colored reflective sunglasses or the shell of some iridescent beetle. They narrow the bandwidth of the incoming light. Between the bandpass membranes and signal processing in the brain, a yinrih can shift the spectrum they're seeing to get a better idea of what they're looking at. They can see a much wider range of wavelengths than humans, possibly all non-ionizing radiation, from basically DC to near UV.

Their torso is also mostly canine in appearance. Humans often mistake yinrih for medium to large dogs at a distance, although their limbs also suggest lemurs or baboons. It's their limbs I'm having the hardest time with. They walk on the palms of their paws like a lemur. Both their front and back limbs have the same range of motion as a human arm. The yinrih can't walk upright, however. One thing I have yet to determine are whether their hind feet are plantigrade or digitigrade. I want to maintain a largely canine appearance, but I also want them to be able to use their hind feet to manipulate objects.

They have six digits per paw. When their paws are planted on the ground, they have an inner thumb, four fingers, and an outer thumb. The first joint of each digit is hairless, as is the palm. This gives rise to one of their human nicknames of “dog possums”. their digits and palms have pads, with the palmar pads of the forepaws being the major instance of sexual dimorphism. Males have a single full palmar pad, while females have several smaller pads surrounding a lactation patch. The lactation patch will start sweating milk when it comes in contact with saliva, usually from a kit licking it in an attempt to nurse. As an aside, clerics collect their own milk and use it like holy water.

The big “feature” of their paws is the writing claw. There's a musk gland located in each forepaw, with a duct leading to the tip of the claw on the digit next to the inner thumb (analogous to our index finger). The writing claw is shaped differently than the rest of the claws and acts like the nib of a fountain pen. The yinrihs' non sapient relatives use this writing claw to mark territory. They excrete a blue-black ink that smells like petrichor. The yinrih evolve a written language out of this scent marking behavior. This allows them to preserve information across distance and time as soon as they achieve sapience. Even though they've only been sapient for about a hundred thousand years (which I believe is actually less time than modern humans have been around) they're able to gain spaceflight a mere five millennia after gaining sapience, and are at Kardashev level II by the time humans discover agriculture.

Their tail is prehensile. It is actually more like an elephant's trunk, being made of pure muscle rather than being an extension of their spine. They can easily hang from their tail, contributing to their human moniker of “dog possum”. They often pull small carts behind them with a handle held in their tail.

As far as locomotion, they're built mostly for arboreal movement. They evolved in a tropical rain forest river basin that floods regularly. They spent the dry season equally on the ground and in trees, and would stay in the trees during the wet season. This arboreal lifestyle is why they have grabby paws and tail. It also means they take to zero gravity like a duck to water. While they normally have to walk on all fours on the ground, they can float in zero-G and use all five limbs to hold and manipulate things. There's a large population of spacers who choose to live permanently on orbital colonies with no gravity. The missionaries that find Earth depart from such a colony, and some of them have never set foot on a planet's surface before landing on Earth.

Regarding evolutionary history, their nonsapient ancestors had populations on either side of the river, with the southern population gaining sapience while the northern population remains irrational. These non sophont relatives are called “tree-dwellers”. They're cute as babies but get violent as adults (not unlike chimps, actually). Humans have a very hard time telling the two species apart, leading to some off-putting situations when they see what look like sapient yinrih in zoos. The two species are similar enough that the yinrih use tree-dwellers for organ transplants and lab testing. There's even a faction of yinrih called the Atavists who regard sentience as a curse and want to return to being irrational animals. “Reject smart tree doggo, return to stupid tree doggo.”