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Rationalising the Irrational, AD&D Science

I have adapted and explained several canon creatures and phenomena to provide a self-consistent, logical ecology that doesn't violate1) basic laws of biology, physics, and chemistry, or require a SSCV Thialf Crane Vessel2) to suspend disbelief.

Human Kin

Probably the oldest definition of men came from the German root men--"to think"--and meant "one who has intelligence". The sense of "an adult, male human being" was of rather late origin. (In Old English, "man" was an indefinite pronoun; classical Latin had two words, homo, "human being", and vir, "adult male human being".)

Human kin (humankin, mankin) means the former, and the classification includes nyxmeasells, galeb duhr, minotaurs, pegasi, unicorns, winter wolves, corvids, leviathans, dolphins, and many other intelligent creatures.

Humanoids, as the word is used in AD&D, do not exist. A species is often defined as the largest group of organisms where two hybrids are capable of reproducing fertile offspring. Or, in gaming terms, if two half-elves mate and she becomes pregnant, they have proven that humans and elves are a single species. Only if reproduction between humans and elves produced sterile half-elven offspring (like mules and ligers) could an argument be made that elves and humans are of different species, but that is not canon. Orcs, elves, dwarves, goblins, gnomes, and more interbreed enthusiastically with humans and with each other; the resultant hybrids are all fertile, and therefore human. Race is an arbitrary, socially-constructed categorisation of people, usually based (discriminatorily) on some combination of various physical characteristics with no biological significance. (If one must differentiate, a more accurate term for the different populations would be breed.)

The work of preeminent biologist J. Craig Venter, who created a definitive molecular portrait of a diploid human genome, states that, in terms of DNA sequence, all humans are 99.5% similar to any other humans, yet at least 44 percent of an individual's alleles are heterozygous. This genetic variation within the individual fully justifies great differences between breeds of humans--elves, dwarves, orcs, etc--but genomic uniformity means that there are some absolutes. For example, all hominids are air breathers (no, sea-elves do not have gills), have blood that is bright red when its haemoglobin is oxygenated and dark red when it is deoxygenated (no blue haemocyanin)--in short, none of the absurdities that are found in several of the source books have any validity, and they will be disdainfully ignored.

That doesn't mean there are no differences. A good example of allowable variation is that found in dogs. The same degree of genomic similarity in humans appears to apply to Canis familiaris (Canis lupus familiaris) as well, yet dog breeds show more variation in size, appearance, sensory acuity, behaviour, and even life-span than any other domestic animal. Bloodhounds (and gnomes) have hyperacute senses of smell, chihuahuas (and goblins) have the best hearing, and so forth. However, the similarities far outweigh the divergences.

One area that deserves further extrapolation is pigmentation. On Earth there are three basic types of melanin. Eumelanin is composed of oligomers or polymers (probably 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA), but that is not yet indisputably established). It is found in eyes, hair, and skin, colours hair grey, black, yellow, and brown, and is more abundant in peoples with dark skin. There are two different types of eumelanin, which are distinguished from each other by their pattern of polymer bonds. The two types are black eumelanin and brown eumelanin, with black melanin being darker than brown. A small amount of black eumelanin in the absence of other pigments causes grey hair. A small amount of brown eumelanin in the absence of other pigments causes yellow (blond) colour hair.

Pheomelanin is also found in hair and skin in both lighter and darker skinned humans. Chemically, pheomelanin differs from eumelanin in that its oligomer structure incorporates benzothiazine units which are produced instead of DHI and DHICA when the amino acid L-cysteine is present. In general women have more pheomelanin than men, and thus women's skin is generally redder than men's. Pheomelanin imparts a pink to red hue; as might be expected, it is found in very large quantities in red hair. It is also particularly concentrated in the lips, nipples, glans of the penis, and the vagina.

Neuromelanin is the dark pigment present in pigment-bearing neurons of four deep brain nuclei: the substantia nigra; the locus ceruleus ("blue spot"); the dorsal motor nucleus of the vagus nerve; and the median raphe nucleus of the pons. Although the precise functional nature of neuromelanin is unknown in the brain, it may be a byproduct of the synthesis of monoamine neurotransmitters for which the pigmented neurons are the only source. (The loss of pigmented neurons from specific nuclei is seen in a variety of neurodegenerative diseases.)

From these examples it can be reasonably postulated that other related melanins could have evolved. On my worlds chloromelanin is produced in the melanocytes by the oxidation and subsequent polymerisation of threonine. It is most prevalent in the orcish population, and imparts a greenish cast to the skin. Unlike eumelanin and pheomelanin, which arise from amino acids that can be synthesised by the body, its production is dependent on an adequate intake of threonine.

In the real world eye colour is also produced by eumelanin, with pigmentation dependent on the concentration of melanin in the iris pigment epithelium and iris stroma, and the actual cellular structure of the stroma (and only varies from light brown to black). Blue, green, and grey eye colours result from the Tyndall scattering of light in the stroma absent a large quantity of melanin; they are structural, not pigment, colours. (A genetic mutation affecting the OCA2 gene resulted in the creation of a "switch," which limits the production of eumelanin in the iris, effectively "diluting" brown eyes to blue.) However there is no biological reason why other pigments could not be present. In my universe small amounts of eumelanin and pheomelanin produce violet eyes, brown eumelanin and chloromelanin produce the dramatic green eyes common amongst elves.

Giant Spiders

Oxygenation--lung capacity and efficiency--is the greatest limitation to insect and arachnid size. On Tamaranth book lungs evolved that over time (aeons) grew thinner and far more complex, with many hundreds, even thousands, of folds; they resemble branchiostegal lungs in several particulars. Bellows are provided by two "respiratory legs" (extend, contract, extend, contract, analogous to buccal pumping or the crocodilian hepatic/pelvic piston) to improve air flow.

Circulation is closed, instead of open, and a logical evolutionary progression from their smaller cousins and Terran counterparts that have a semi-closed (not truly open, as in one cavity…they have arteries, but not veins) system.

Exoskeletons are not radically different, merely some improvements in the chitin/sclerotin/calcium carbonate composite (which, in various proportions, is what Terran insects and arachnids actually use) to make it somewhat thicker, stronger, and more supple. The most significant alteration is in moulting, which is done in chunks, so that there is always some visceral support; they don't so much moult as crack and accrete (the exoskeleton cracks, soft tissue expands, new exoskeleton forms in the gaps, and so forth).

Additionally, there is a huge growth spurt as the first exoskeleton is forming (advantageous for the species, if not the individual). Eggs are laid in secure, sealed breeding chambers. Thousands of spiderlings hatch, but only a dozen (more or less) emerge when they're big and strong enough to open the chamber, in the meantime having feasted on their smaller, weaker, slower, or unluckier siblings.


Owlbears are monotremes. Their beaks are an example of convergent evolution. The most anterior bone of the upper jaw, the pre-maxilla, grows downwards to overhang the lower jaw, ending in a single, very sharp, thick, and strong exposed incisor. Oblique wear hones the contact between the continually-growing upper maxillary and lower dentary teeth, providing an efficient cutting surface. Other than in superficial appearance, the beak is not greatly different from an elephant's tusks, or even a beaver's specialised front teeth. Owlbears don't have feathers; rather, they have a double coat of fur, the inner soft, downy, and insulating, the outer much coarser, and tending to form feathery tufts.


The roc is a lie. There are no eagles with 120 foot wingspans (because, aerodynamics…) What does exist (on Tamaranth) is the azhdarchid, which absent a mass extinction event, continued to evolve.

Azhdarchid (Spear-bird; Roc)

Climate/Terrain: Temperate
Frequency: Rare
Organization: Nest of a solitary female bird or a mated pair and their young; males do not build nests
Activity Cycle: Diurnal
Diet: Predominantly carnivore
Intelligence: 3
Treasure: Nil
Alignment: Neutral
No. Appearing: 1 (+20% chance for 1 juvenile) or 2 (+75% chance for 1d2 young) 1)
Armour Class: 3
Move: 9" ground / 96" flying (Manoeuvre Rating: C)
Hit Dice: 10 + 8
THAC0: 8
No. of Attacks: 3
Damage / Attack: 2d10 (beak) / 2d6 (wing) / 2d6 (wing)--only 1 wing can hit any single target of large or smaller size in a round
Special Attack: Spits nerve poison once per three turns, Save vs. Paralysis
Special Defence: Blunt weapons inflict only 1/2 damage
Magic Resistance: Nil
Size: Gargantuan
Morale: Steady, if young are absent; Fearless, if young are present
XP Value: 3000

With an average 50 foot wingspan, 15 foot neck, and 6 foot beak, the azhdarchid is the largest bird on Tamaranth, and is an apex predator. They have black crests, black beaks, black or dark grey markings, and white necks with distinct breast feathers; their wings and underbellies are a shade of grey that can range from pale, softly-dappled near-white to dark, bluish slate, sometimes mottled with white or lighter grey. Their bodies are thin and compact, and they are amazingly light for their size.

They are extremely long-lived birds, with a life expectancy estimated to be between 150 and 200 years. The oldest known specimen whose age can be reliably verified was 212 at the time of her death. They breed no more often than once every three to five years, and, although they reach sexual maturity at around 10 years, a female seldom lays her first egg before she is 20 and has reached her full, adult size and weight. Courtship begins in the spring and involves sexual displays, nest building, and considerable physical contact, with the male preening and stroking the female, and rubbing against her cloacal opening. Without this assiduous stimulation, the female does not ovulate. Mating occurs in late summer and results in a single (enormous) white egg that incubates over the winter, producing an altricial hatchling in early spring.

They are categorised as cavity nesters. When a female leaves her mother's nest she will find a cave or other enclosed area that she claims as her own, fiercely defending her territory from all interlopers. Unattached males may occasionally shelter in caves during inclement weather, but usually do not limit themselves to a single area, ranging far and wide in search of food and desirable mates. During courtship both parents will work to thickly line the nest with soil, branches, sticks, twigs, leaves, seaweed, and other vegetative matter. The heat generated by the decay of these mounds, which are in effect giant compost heaps, helps warm and incubate the egg through the cold winter. The chick is not fledged until the following spring, and does not leave the nest until becoming sexually mature. The male remains with the female and shares parenting duties at least until their offspring is fully fledged, and sometimes longer.

They are predominantly shore birds, usually nesting in high, rugged, sea-side cliffs, and feeding mostly on aquatic mammals, large fish, and squid, but they have also been sighted on lakes and rivers, or in marshes. They are at home in both salt and fresh water.

They hunt in one of two ways. On land or in shallow water they stand motionless, waiting patiently for prey to come within reach, then strike out with lightning speed, moving only their necks and heads, impaling their quarry with their wickedly sharp beaks. Their long, supple, powerful necks convey quite an unexpected advantage of reach. This is the method they use to take salmon after salmon during spawning season. At sea their extremely keen, binocular vision allows them to spot prey from a great distance and to accurately judge its depth underwater. They land on the water and spear their target, striking accurately to a depth of 15 feet. However, their senses of hearing and smell, whilst quite good, are not exceptional; if they can not see their prey, they usually can not catch it.

They prefer to fly by dynamic soaring, using the gradient in wind speed that exists between the sea surface and higher up, or to take advantage of the curtain of wind deflected up from the windward face of a wave--so-called slope soaring. Both methods of flight are fast and efficient, allowing them to conserve energy.

Taking off from land is difficult for azhdarchid; they need a long airstrip. They run into a head wind--the stronger the wind, the easier it is for them--or they launch off a cliff edge if the wind is blowing into the cliff. It is much less trouble for them to rise from the water; they are strong swimmers, paddling along smoothly until they get up to speed.

They are not migratory, and inhabit a range between roughly the 20th and 50th degrees of latitude. They avoid the tropical regions because of the erratic weather patterns; the stagnant calms and violent thunderstorms make it very hard for them to fly. North of the 50th parallel the weather is too cold for them.


Age (yrs) HD THAC0 Attacks Notes
Hatchling (0-2) 1 Only found in nest; no attacks or defenses
Fledgling (3-5) 2+4 19 1-2/1/1 Will first attempt to fly away; if cornered, will spit (uses adult THAC0) and then fight
Juvenile (6-10) 4+4 16 1d10/1d6/1d6 Morale: Unsteady; will still spit first, then fight

Galeb Duhr

Climate/Terrain: Mountains above 7000 ft
Frequency: Very rare
Organization: Family
Activity Cycle: Any (seasonal variation)
Diet: Scavengers
Intelligence: 10-18
Treasure: 1/2Q
Alignment: Neutral good or any
No. Appearing: 1-4
Armour Class: -5
Move: 1
Hit Dice: 8-10
No. of Attacks: Special
Damage / Attack: Special
Special Defence: Bladed weapons lighter than a hand-and-a-half inflict no damage; all other non-concussive weapons inflict 1/2 damage
Magic Resistance: 30%
Size: Large
Morale: N/A
XP Value: 1000

Anatomy and Physiology

It is a common misconception that mutations happen "because of" or "in response to". They don't. Mutations happen. Only time and environmental conditions can determine whether they are beneficial or detrimental to the organism and to the long-term survival of the species.

Some authorities3) believe that silicate minerals in water played a crucial role in abiogenesis. They replicated their crystal structures, interacted with carbon compounds, and were the precursors of carbon-based life. However only a very few present-day organisms use silicate, or silicic acid (H4SiO4), as an important nutrient: diatoms, radiolaria, silicoflagellates, siliceous sponges, and galeb duhr.

The galeb duhr are curious boulder-like creatures with retractable appendages. These intelligent beings are very large and slow-moving. They live in cold mountainous areas, although they have been seen at lower elevation during winter. A typical adult galeb duhr is about 8 feet tall; the largest specimen ever observed was reputedly approximately 12 feet tall. When not moving they look like part of the terrain they live in.

Taxonomists agree that galeb duhr are eukaryotes, but beyond that point of consensus there is room for lively debate. They are generally placed in the Kingdom: Animalia and Phylum: Chordata; some contend they are members of the Subphylum: Tunicata, although other scholars, equally erudite, maintain they belong in their own Kingdom, one shared only with their more primitive, extinct ancestors, for their morphology and physiology have several unique characteristics. In common with most life forms, they are carbon based, but like diatoms they incorporate silicates into cell walls, delicate strands much finer than asbestos, like reinforcing threads woven into a complex carbon tapestry. Upon gross physical examination, their integument appears to be solid rock; in actuality it is living, vascular tissue covered by an outer layer (carapace), roughly analogous in formation and protective function to completely keratinized human epidermal cells (calluses), that is almost completely siliceous.

However, if a galeb duhr is cut open, one finds bright red organs embedded in a stony matrix, a structure similar to that of certain tunicates. Whilst the cells of the dermis, skeletal structures, and parts of their digestive systems have cell walls impregnated with silicates, the cells of most of their organs and tissues have only cell membranes, and the systems themselves, although anatomically different, are very similar functionally and histologically to analogous structures found in mammals, birds and reptiles.

In the centre of the body is a hollow column of silicate "bone" that contains the neural tube (notochord) and brain; it is narrowest at the top, widening to a broad oblate at the mid-point of the body, forming a "skull", then narrowing again. It is perforated for its entire length by numerous foramina that permit the passage of spinal and cranial nerves. It differs markedly from a vertebral spinal column in that it is completely rigid. The brain is very large and convoluted with a prominent and well-developed cerebral cortex. Both the brain and the nerve bundles are highly vascularised. The neural bone rests on the inferior wheel bone near the base of the body; the juncture between the neural bone and the inferior wheel bone is called the hub.

Around the superior crest of the galeb duhr, well-protected in fissures in the carapace, are twelve evenly spaced pores or nares, leading to a single, multi-lobed, highly efficient circulatory lung that encircles the neural column and leads to several air bladders. In an interesting example of convergent evolution, the lung most closely resembles that of birds, with oxygenated air constantly flowing in a single direction through it, and gas exchange occurring in millions of tiny parabronchi that, on a cellular level, are nearly indistinguishable from those of avian species. The respiratory system comprises 20% of the total body volume; the great inferior air sac plays a key role in ingestion.

Nestled within the lung area is a large, four-chambered, very muscular heart allowing for efficient nutrient and oxygen transport throughout the body. Circulation is closed; they have arteries, veins, and capillaries.

Like snails they move by means of an extremely muscular foot, flexible and powerful, that completely encircles the underside of the body; they can move in any direction without turning around at a speed of approximately 10 yds/min (1/3 mi/hr or 4 mi/day), pulling themselves along by means of elongating and contracting their muscles. This foot has a thin integument layer (no thicker than the skin of a vertebrate) on the top and sides, but the sole is considerably thicker, and is equipped with sharp, spiky dermal denticles that act as both teeth and cleats.

Galeb duhr are the ultimate omnivores. Primarily scavengers, they are able to extract energy and nutrients from virtually any organic material, including organic minerals, and some inorganic ones. Low-growing plants and grasses, leaf mould, insects, worms, mollusks, carrion, even lignite and soft silicates (such as talc, kaolinite, and mica) are all consumed. They tread back and forth over their food, using their foot denticles to break it into small fragments, and then suck it into their crops by means of air pressure, provided by the constriction of the great inferior air sac, through their mouths which are located near the centre of their underbellies.

In the crop, the only internal organ that incorporates silicates in its structure, the food is softened by a very watery "pre-saliva", and further pulverised by strong muscular churning and by smaller denticles that line the crop walls, then moved by peristalsis into the gizzard where muscular bands rotate and further crush the food by shifting it from one area to another. The gizzard also secretes "true saliva" which contains amylase (to begin the breakdown of starch) and an alkaline mucus (which lubricates the food and provides the pH necessary for amylase to work).

Once reduced to slurry, it passes into the first stomach, also called the rumen, where specialised microorganisms decompose cellulose and other carbohydrates into volatile fatty acids, acetic acid, propionic acid, and butyric acid. These microbes also synthesize amino acids from non-protein nitrogenous sources, such as urea and ammonia. As these microbes reproduce in the rumen, older generations die and their cells continue on through the digestive tract where the cells themselves are digested, providing another high-quality protein source. The food bolus next passes into the second stomach which secretes proteases and powerful gastric acid, acid so strong that no known pathogen can survive exposure to it; some proteins are fully digested and absorbed in this stomach and others are partially digested before the chyme moves into the intestine.

The first intestinal segment, the duodenum, where most chemical digestion takes place, is about three times longer than the duodenum of any mammal of comparable body size. The pancreas, equal in length to the duodenum, lays adjacent and distal to it; the liver, not quite as long but between two and three times greater in girth, is proximal. Ducts connect the pancreas and liver to the duodenum at several places, secreting digestive enzymes from the pancreas and bile from the liver, at each juncture optimising the pH and concentration of specific enzymes and hormones necessary to digest a wide variety of foods. This remarkably efficient system is how even lignite, reduced to fine particles in the crop and gizzard and further broken down by the gastric acids before passing into the basic, enzyme-rich environment of the duodenum, yields easily absorbed fulvic acid and other essential nutrients. All three organs, encased within and supported by the mesentery organ and resting on the spoke bones, curve in a gentle clockwise spiral distal to the more centralised mouth, crop, rumen, and stomach.

Most absorption occurs in the jejunum. Approximately half again as long as the duodenum, it continues the gradual outward spiral of the digestive tract,4) and is full of long, brushlike villi extending from the extremely erose inner surface, maximising the surface area available to absorb nutrients.

The ileum, the final and shortest portion of the intestine, follows the jejunum and ends at the junction where the terminal ileum communicates with the cloaca through the ileocloacal valve. It lays in the broad, shallow digestive groove of the felloe bone, and like the duodenum and jejunum is contained within the mesentery that carries the blood vessels supplying them, lymphatic vessels, and nerve fibres. The ileum is richly colonised with symbiotic bacteria responsible for the synthesis of necessary vitamins, including K and B12. Digestion is too vigorous to allow sufficient absorption of vitamins from dietary sources, but their gut flora produce all they need.

Able to digest and assimilate almost everything they consume, galeb duhr produce very little waste. What little remains passes through the ileocloacal valve into the inferior portion of the cloaca where water is absorbed before the pellet-like faeces are excreted through the common cloacal vent.

Galeb duhr have a single, large, horseshoe-shaped reniculate kidney that partially encircles the neural column just above the crop; it drains into the superior portion of the cloaca through the P-shaped ureter; the loop deters bacteria from travelling up the ureter and causing infection. It functions in almost the same way as mammalian and avian kidneys; the cortex makes up around 60% of the kidney's mass, while the medulla is considerably smaller at about 30% of the mass, with blood vessels and other tubes make up the remainder. The abundant nephrons notably feature distinctive loops functionally identical to the loops of henle seen in mammals.

Galeb duhr are simultaneous hermaphrodites, with each healthy adult having one fully functional ovary and one testis, but can only reproduce sexually, i.e. they can not self-fertilise. During mating two soft, flexible, highly innervated tubes, one terminating in fimbriae around the ostium (the phallus), the other slightly flanged (the oviduct), extend from the genital fissures of both partners. Prolonged stroking and stimulation with and of these tubes precedes copulation, and results in turgor and the secretion of lubricating fluids. When a state of excitation has been achieved, the fimbriated tube engulfs the flanged tube, drawing it inside until a secure connection has been achieved, and the partners, simultaneously or sequentially, ejaculate sperm into the other's oviduct. Mating is reported to be highly pleasurable, and is practised recreationally as well as reproductively. They are induced ovulators, with ovulation-inducing factor in the sperm stimulating the development of follicles in the ovaries. It usually takes no fewer than 5 to 7 matings occurring no more than 24 hours apart before an immature ovum begins to develop, and a further 3 to 5 days before it has matured and descends into the infundibulum, in galeb duhr an open sac or fold in the oviduct, where fertilisation occurs.

However, galeb duhr are semi-viviparous; the conceptus remains attached to the ovary for approximately 45 days whilst the yolk grows large enough to nourish the foetus for the duration of gestation, a distinct amnion, chorion, and allantois form, and the embryonic stage of development is completed. During this time oxygen and nutrients are provided, and wastes are eliminated, by the mother. However, as the conceptus grows larger and heavier, the infundibulum can no longer support the increasing mass and the egg drops further down the oviduct into the magnum, attenuating and then breaking its initial connection with the mother's blood stream. In the magnum the egg (including the yolk, blood vessels, allantois, amnion, chorion, and amniotic fluid as well as the foetus) is given a thick coating of watery albumin to both nourish and cushion the foetus, and a thin membrane to contain the albumin. It then moves into the uterus where it will remain for the next 90 days. The membrane thickens to a leathery shell and is enfolded by the vascular uterine epithelium, which provides the foetus with oxygen and assists the allantois with removing wastes. However, the mother no longer directly provides nutrients as placental animals do.

When gestation is nearly complete the egg enters the cloaca and passes through the common vent. The vent is normally closed by two panels externally indistinguishable from the rest of the carapace but considerably thinner. When the cloaca is full, the evacuation reflex causes strong muscular bands to simultaneously pull the vent open whilst pushing out the cloacal contents. Urination and defecation require minimal exertion. However, with a circumference between 25 and 28 inches, the egg fills the cloaca, and laying is sometimes a prolonged process. In the event of extreme muscle fatigue, the panels will close, sometimes spasmodically, often crushing the egg and killing the foetus, but permitting the broken egg to pass more easily, preserving the life of the mother.

Between several hours to three days after being laid, the egg will hatch and a single semiprecocial, nidicolous offspring will emerge. Although the infant looks very much like a miniature version of the parent, the carapace is still very soft. The first meal the hatchling eats is the remains of its yolk and shell; the next several are "crop milk" brought up by the parent from their rumens. It is essential that beneficial bacteria colonise the sterile infantile digestive tract in the first few days whilst the stomach acid is still weak; bacteria from the parental cloaca on the egg remains and in the crop milk from the rumen provide for this. By the time the infant is a month old, it can digest anything its parent can, although it may still need help cutting its food into manageable pieces.

Although independent of its parents for its physical needs within a few weeks, a child remains with its parents, developing intellectually and socially, until reaching sexual maturity at about 20 years, sometimes (in resource-rich territories) much longer, raising a family of its own beside its parents.

they may be slightly bent, stretched, or evaded, but none are outright broken
an electric hoist may still prove useful
A. G. Cairns-Smith; Richard Dawkins
galeb duhr have none of the tight loops and flexures characteristic of mammalian intestines
croiduire/miscellaneous/rationalising_the_irrational_ad_d_science.txt · Last modified: 2018/08/10 02:04 by Croi Duire