The first of Alterra's races, the trolls, comprise just under a third of the planetary population. Like humans, the trolls of Alterra have been altered from their state in the original universe, both socially and biologically.
The first group of alterations to Trollish society had to do with the raising of the young. The Alternian structure, in which the young were essentially self-raised with the aid of lusi and robots, proved to be unworkable without the advanced technology levels attained by Alternian civilization. Having had harsh lessons in what happened when you skipped developmental steps, the gods were reluctant to simply give the initial trollish clans technology beyond the most basic levels (fire and metalworking and the domestication of animals and the like). As a result, trollish civilization was for many centuries arranged in broods, each brood being the offspring of a single Mother Grub. The trolls of a given brood would work together to raise the wigglers of that brood (though those who followed the path of the Sylph tended to take the lead in this matter). The role of the lusus, though diminished, remained essentially what it was on Alternia. Over time, as technological levels rose, multiple Broods merged together, creating the first trollish cities, but the communal method of raising wigglers remained largely unaltered.
The other major social alteration, not to mention the most significant biological changes, had to do with the hemospectrum. The biological portion of the hemospectrum remained for the most part unaltered. Whether or not the Gods could have left the rest of the trollish biology intact while abolishing the blood-based subspecies, they had no desire to do so.
The social implications of the hemospectrum, however, were completely rewritten, largely without the gods even having to get involved. In the case of the sea-dwellers, their preference for aquatic life caused many of them to become hermits or recluses, dwelling in isolation or small communes of their own kind under the sea. Though a few rose to high rank in early Trollish society, this number was quite small compared to those from most other bloodlines, due to a combination of the above-mentioned tendency towards reclusion and the low numbers of sea-dwellers actually born. The purple-bloods, unfortunately, suffered from a much nastier handicap. Due to their shared blood color, purple-bloods are uniquely vulnerable to the influence of the Clown. Normally, a mind must be somehow "broken" for the Clown to gain access to it, but a purple-blood's biology gives the Clown a chink though which to whisper. Though he can do little but whisper without further mental damage to open the chink wider, mere whispers can still do a lot. Though the purple-bloods have their share of leaders, heroes, and well-beloved, they have a disproportionate number of madmen, cult leaders, and serial killers.
Below the purple-bloods, things evened out to a much greater degree. Though those of higher blood are individually somewhat more likely to attain wealth and power (due to a longer lifespan and resistance to psychic manipulation), the more numerous births lower down the spectrum balance this out, to the point where no color had or has any consistent "edge" over the others.
The one major biological change to the hemospectrum was more or less the result of another change. In order to facilitate harmony between their races, the Gods altered the genetics of both humans and trolls to render them interfertile. The alterations were a success. Human genetic material, provided to a troll Mother Grub, would in fact produce wrigglers. But the wrigglers belonged not to any of the eleven previously known blood colors, nor even to the quasi-mythyical lime-bloods. No, these human-descended trolls shared the candy-red blood of humans. And when these "candybloods" provided their genetic material to the Mother Grub, those embryos would themselves have a chance to bear this new shade of blood. The candybloods proved something of a wildcard element in Troll society, and did more than almost any other caste to disrupt any attempt by the Abhorred to restore the old hemospectrum. For while the eleven other shades had the nature of their psychic gift determined by their bloodline, with only the strength varying by individual, the candybloods' psychic gifting was as random as it was among the humans. Some candybloods manifested telekinetic powers, some were telepaths, some possessed the physical enhancement and mental shielding of the "highbloods", some had weak versions of all three.
In addition to their psionic powers, trolls also have access to magic where granted by the gods.
The second of the three sapient races of Alterra, the humans comprise a bit less than two-thirds of the planet's inhabitants. Like all three races, they are bipedal, with two arms and general bilateral symmetry. Humans come in a wide variety of skin tones and hair and eye colors. Unlike the trollish hemospectrum, these distinctions have at most extremely minor physiological implications.
Humans generally reproduce via internal impregnation through heterosexual intercourse. That "generally" would until fairly recently have been an absolute, but some decades back a group of geneticists (with the aid of some Sylphcrafters), created what is essentially a much smaller and slightly modified version of the Mother Grub, which can take gametic material from two humans and attempt to grow a fetus therewith. Though this method does allow for same-sex reproduction, it has a much lower proportional success rate than heterosexual intercourse, meaning that the children of same-sex couples still constitute an extremely small fraction of the total human population. In addition, thanks to the Thirteen's engineering, humans and trolls are interfertile. If a human and a troll engage in internal sex, they will produce human offspring (though such offspring will have a tendency towards grayish skin and discolored blood).
Such interbreeding would doubtless have caused humans to evolve into a psionic race over time, but the Thirteen chose to jump the gun, imbuing humans with the same sort of psionic powers that the trolls possessed. Though humans on average wield slightly less psionic power than trolls, the strength of the gift varies wildly, just as it does among trolls. The precise nature of any given human's psionic abilities appears to be partially hereditary, partially based on the individual's own personality and influences, and partially random. Humans are also, of course, capable of using magic if it is granted by one or another of the Gods.
The third race of Alterra, the carapacians, are by far the rarest, comprising roughly a thirteenth of the planet's population. While carapacians have been altered to allow them to reproduce on their own, the Gods also retain the knowledge necessary to grow new carapacians, and are known to do so on occasion. In more modern eras, this knowledge has also entered mortal hands, though the Thirteen have made it very clear that their wrath will descend on any attempt to enslave mortal-grown carapacians.
Carapacians may be divided into five distinct castes:
Pawns are by far the most common of the carapacian subcastes. They are bipedal, with a head, torso, two arms, all the normal anatomical features, and no odd alterations. Though somewhat physically weaker and more fragile than humans or trolls, they are capable enough. Like all carapacians, pawns possess no form of psionic power, though they are as capable as any other race of using magic. All natural-born carapacians are born as pawns, and indeed pawns are one of only two carapacian castes capable of reproduction. However, a certain fraction of pawns will, upon reaching the appropriate portion of their life cycle, go through what is essentially a form of metamorphosis, and transform into one of the other four castes.
Rooks are marked by their bulging muscles, their vast strength, and the odd castle-shaped deformities upon their backs. They tend to fill something of a heavy labor role, especially as their transformation tends to actually diminish their intelligence.
Bishops are marked by their high crests (actually part of their body) and the distinctive scepters they usually bear. They are known to possess mystical abilities that are neither psionic nor magical, but the precise nature of those powers remains fairly obscure.
Knights bear some resemblance to the musclebeast lusii in physical form. They are generally something of a warrior caste, acting as the core of a carapacian kingdom's armies. To fit this role, their carapace is much more durable than the norm.
Royals are by far the rarest caste, and in fact any given carapcian city-state will have precisely two of them at any given time-a King and a Queen. Should one of them die, a suitable Pawn will within a few days undergo metamorphosis to replace the loss. The King has a size and build reminiscent of a Rook, though without the castle-like deformity and with somewhat less grotesque musculature. He is also far more intelligent than a Rook. The Queen, meanwhile, resembles an enlarged Pawn, standing somewhat taller than her counterpart (though of course far more slender). The Royals are, as the name suggests, the leaders of their city-state, with obedience to their authority seeming hard-coded into the carapacian genome. Royals, like Pawns, are fertile.