Hrihriwa
Biology, culture, and natural history

The hrihriwa are a race of human-horse shapeshifters. They live in clans of a few dozen to several hundred individuals and often incorporate humans and horses into their clans. They are found all throughout the Rootspan, but tend to cluster in remote and inhospitable areas, particularly in the central root mountains and on the steppes by the outer ring.

As the Rootspan lacks large domestic animals, hrihriwa are highly valued for their speed and physical strength. Yet due to their seclusive nature, few hrihriwa willingly become laborers. As such, they are often tricked, extorted, or enslaved by humans and city-dwellers. Where ranges overlap, hrihriwa have an amicable relationship with redlings and wardens.



Anatomy
At a quick glance, a hrihriwa may seem like a regular human or horse (depending on their chosen form), but both of these forms have distinct traits that set them apart from their look-alikes.

As humans, hrihriwa have large, pointed ears, which move in response to stimuli and emotions. They may pin their ears against the skull in fear or fury, flare their ears in excitement, or flick them in annoyance. This is a semi-conscious movement, like facial expression, and may be controlled with great willpower.
Their midfaces are long, their noses somewhat flat, and their chins soft, making for an appropriately "horse-like" appearance.

In their human form, hrihriwa also sport rather large eyes, always in seemingly-impossible colors. They span the entire chromatic spectrum, from red to yellow to blue to magenta, and always highly saturated. Their hair spans the entire equine color spectrum (and is of a similar coarse texture as horsehair), while their skin spans the entire human spectrum. Their skin color seems somewhat tied to elevation - darker skin is common at higher elevations, particularly around the trunk of the World Tree, while lighter skin is common on the steppes near the Rootspan's outer ring. However, due to migration and displacement, there are many exceptions to this rule.

There is very little sexual dimorphism between their males and females (or 'stallions' and 'mares,' as they call themselves). Mares have very small chests, somewhat boyish hips, and a tendency to grow sideburns. Stallions have narrower shoulders and wider hips than most human men (though this point of difference is not very pronounced), and are unable to grow full beards. They're of average height, compared to humans, though of a slightly more wiry build. There is no difference in stature between the sexes.

As horses, they retain their brilliant eyes, including the white scleras and round pupils, which may be a disconcerting sight on a horse to the unitiated. They're of a rideable size (the only rideable equines in the Rootspan), though they loathe to let anyone ride them (see also societal relations re: mounts). A hrihriwa's horse form is typically as tall as their human form, measuring by the poll. Their coat, of seemingly any color found in regular horses, is short and without any feathering. The may have curly coats, but they only grow moderate winter coats, likely as a result of the Rootspan's subtropical environment.

As horses, they have a slender build, akin to a light carriage horse or a lady's pleasure horse, with a high-set neck and a high-stepping bouncy gait. They are gaited, though the full range of their gaits is unknown. When asked, they will simply say that they can walk, trot, and 'run.' Walk, trot, extended trot, canter, gallop, pace, and something akin to a saddle rack or running walk has been observed. They are also quite fond of dancing in their horse forms, which includes tempi changes, passages, pirouettes, and airs above the ground.

No hrihriwa has been dissected yet, so little is known of their internal anatomy. Hypotheses will be discussed in the chapter on biological functions.

Shapeshifting The most distinctive feature of the hrihriwa is their ability to change between these two forms. The transformation is not instantaneous or logical. Every individual has a distinct transformation process, and most can learn to control the process and degree of transformation. The average transformation lasts 5-10 seconds. It's most common for the transformation to start at the extremeties, though some start at the head or the core of the body. A few apparently start from right to left, or vice versa, beginning with the extremities on one side and ending with the extremities on the other.

When a hrihriwa shapeshifts, whatever clothing and accessories one form wears, are 'absorbed' into the other form. If they wear clothes on their human body, these will simply vanish along with the human body, as the horse body takes over. Accessories as large as saddlebags and weapons have been observed to be 'absorbed' into the horse body, and can be either be 'expelled' from the human body via a partial shift into horse (e.g. by briefly changing the human back into a horse back), or can be retrieved following a full shift into horse.
It is unknown how much a hrihriwa can absorb, but there seems to be some inverse relationship between mass and volume - they may absorb very heavy objects that don't take up much space, or very voluminous objects with a low mass. They can not absorb living creatures, including plants (see also: hrihriwa language re: object pronouns).

Shapeshifting is a voluntary act, though altered emotional states, such as those brought on by panic, trance, seizure, or hashish, may cause involuntary changes. Children ('foals,' 'colts,' or 'fillies') may also change at random or inopportune times, though this behavior has usually been entirely curbed by the age of 10. Some hrihriwa are known to 'sleep shift,' like a human may sleepwalk.

Hrihriwa distinguish between 'uniform shifters,' whose changes proceed in the aforementioned way, and 'erratic shifters,' whose bodyparts change out of order and seemingly at random. One example includes a stallion who tended to first lose his hands to hooves, then grow a horse's lower face, then gain a quadrupedal posture, followed by a lengthening of the neck, and so on. The full change took no more time than that of a uniform shifter, but it was significantly more alarming to watch.

Though all hrihriwa can learn partial shifts, such as only changing ones head or lower body, partial shifts come naturally to erratic shifters.

Being an erratic shifter seems about on par with being left-handed in human communities; it is an ultimately harmless trait, though expressing it often results in reprimands and corrections. Erratic shifters undergo sleep shifts more often than uniform shifters, and they may change unwillingly due to intense emotions, such as joy, fury, or anguish. It does not appear that a 'cure' has been found for erratic shifting.

Highly skilled shapeshifters are able to entirely remove or switch around bodyparts, such as replacing (human) hands with (human) feet, absorbing their own legs, or moving the eyes to the palms. The most voluminous form a skilled shapeshifter can take is a simultaneous human-horse, usually with the two bodies attached at the backs. Upon death, all hrihriwa take on this form, even if they weren't able to purposefully transform into it in life. It is thus considered a macabre show of impropriety to take on a form like this, and even those who can usually won't.
The least voluminous form a skilled shapeshifter can take appears to be a 'core' body cavity (such as a chest), which holds the heart, and the crown of the skull, which holds the brain (see also biological functions re: circulatory system)

For reasons unknown, the hair/mane of both heads are 'linked' in such a way that if one is cut, they other will be too. Thus, a hrihriwa always has the same hairstyle, regardless of form. Hrihriwa have attached much superstition to this (see cultural practices re: hair).



Biological functions Circulatory system During intermediate forms a hrihriwa may at once have four lungs or none at all. This does not appear to bother them. Even when lungs are present, hrihriwa have been observed holding their breath for up to 10 minutes with little effort. Hrihriwa can talk without the presence of lungs, indicating that they have some secondary way of pushing air across their vocal cords. Additionally, the human body and horse body speak with the same voice.

Hrihriwa only have one brain and one heart. Highly skilled shapeshifters may choose to remove vulnerable organs from exposed areas (e.g. by hiding the heart or brain in an unexpected place, like the rump og the horse body), indicating that their circulatory and nervous systems are as malleable as the rest of them. This does not appear to increase the risk of blood clots, heart issues, or internal bleeding. If anything, the opposite is true. Hrihriwa live several decades longer than humans - on average they live 100 to 130 years, though some hrihriwa have reached 150 years.

Eating, aging, reproduction



Natural history
Ecology

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Religion
Religion

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Cultural practices
Clans, gender, diet, clothing

With very few exceptions, all hrihriwa have a two-syllable humantongue name and a horsetongue name that is unpronounceable to humans.