Spread of humans on Zebia

Human migration

• Red: migration before 100 kya
• Orange: migration 100-80 kya
• Yellow: migration 80-60 kya
• Green: migration 60-40 kya
• Dark blue: migration 40-20 kya
• Light Blue: migration less than 20 kya

Migration before 80 kya

Zebian humans evolved in the northeastern corner of Protera around 200,000 years ago, and they are the only living species of their genus. They possess roughly the same physiology as Earth humans. Around 150,000 years ago, they began to migrate out of the region, producing the first genetic split between those who moved south and those who did not. By 120 kya a small group splits off and moves to the east coast, while another group splits to the west, and by 110 kya, has reached the northeastern coast of the inland sea. Now we find a group split off and begin a rapid migration westward along the large peninsula north of the inland sea. Around 90 kya this group even crosses the narrow strait separating this peninsula from the northwestern portion of Protera. This strait is extremely shallow, and a temporary land bridge, caused by silt or slightly reduced sea levels, might have made the crossing easy.

Possibly encouraged by a warming climate, some of those who stayed in the region east of the inland sea start moving south and west about 80 kya. Some of them follow the south coast of the inland seas into western Protera. Also around 80 kya, some humans migrate from their original homeland in the northeast to the island chains immediately west of it. This is one of the many mysteries of Zebia, as only a tremendous drop in sea level would allow for a dry-land crossing to any of those islands. It is therefore very likely that these humans accidentally drifted across on floating rafts of vegetation. Zebia’s extremely swift east-to-west circumequatorial current would have carried them this distance quickly, if such a raft could hold together. There is also a chance that these people developed outrigger canoes, but there is no fossil evidence of such craft on Zebia for several millennia.

Genetic differentiation

At this point, all of the major population groups of Zebian humans are present (if not yet differentiated). The biggest division is between those humans who stayed in the northeast or traveled to the nearby islands on the one hand and those who traveled south on the other hand. The first group will be named Boreoids, and the second group Austroids. The Boreoids are further divided into those who stayed on Protera, called Paleoboreoids, and those who crossed over to the islands, and later, to Tetarta and Pempta. These are referred to as Neoboreoids.

The Austroids are also divided into two main groups, the group which inhabits the east coast, and the group which inhabits everything west of that. The eastern group is called Anatolicoids, and the western group Hesperoids. The Hesperoids are further divided into those who traveled west along the long, snaking peninsula, and those who moved south into the taiga. The northern one of these group is called Dyticoids and the southern group Notoids.

All of these groups are still very close together genetically even in modern times; they do not constitute true "races" in a biological sense. Due to cultural contact from well before the advent of civilisation, the populations on Protera have mixed considerably, and even phenotypes commonly associated with one of the Proteran groups do sometimes appear on other continents. However, some general tendencies as to their appearance can be discerned, and will be outlined below.

Migration after 80 kya

Around 70 kya, the Notoids break through the icy mountains south of the inland sea, and join the Dyticoids in colonizing the west portion of Protera, but from the south rather than the north. By 60 kya, they reach the cold southwest coast with its peninsulas and glaciers, and by 50 kya, they have reached the coast of the strait separating the two southern continents. Meanwhile, the Boreoids have managed to reach Tetarta and begin colonization, settling the entire continent by 45 kya. The crossing to Pempta occurred only in historical times, around 3000 years ago.

Some time around 50 kya, the Notoids cross over to Trita. By 40 kya, virtually the entire continent is inhabited. This settlement results in the extinction of much of Trita's impressive dinosaur megafauna, but a number of species does survive human contact. The same pattern repeats when one group from Trita reaches Deutera around 30 kya. By 10 kya, almost all territories suitable for human habitation are populated. This crossing probably required some primitive boat technology, but again, this is an area of mystery in Zebian history.

Back on Protera, things are shifting around. Around 50 kya, the Notoids move north, displacing the Dyticoids in most of the west, leaving pockets of Dyticoids and lots of genetic mingling. This coincides with a massive migration by the Anatolicoids, who move north (taking over most mainland areas from the Paleoboreoids) and west (taking over the former homeland of the Notoids in the southeast of the continent). It is unclear whether these migrations are causally connected to each other.

The islands west of Protera, the islands west of Deutera, and most oceanic islands remain uninhabited until sea-going vessels are developed.

Population groups

Genetic diagram

(with mention of the main locations of each group in modern times)

• Boreoids
  • Paleoboreoids (northeastern Protera)
  • Neoboreoids (Tetarta, Pempta)
• Austroids
  • Anatolicoids (southeastern Protera)
  • Hesperoids
    • Dyticoids (northwestern Protera)
    • Notoids
      • Paleonotoids (southwestern Protera)
      • Neonotoids (Trita, Deutera)

Basal humans are dolichocephalic (long, narrow skulls), prognathic (protruding rather than flush mouth), with dark skin, sundadont (i.e. typical) dentition, with wide noses and gently sloping foreheads (this is very similar to early humans on Earth). Unlike Earth, the genetic populations that stayed in tropical regions (the Boreoids) tended towards bracchicephalism (rounded skulls), while those groups moving into cooler climates (Anatolicoids and Dyticoids) tended to keep the dolichocephalic head-shape. Notoids have independently developed slightly rounded heads, in appearance between the shapes found in the other groups and therefore termed mesocephalic. The Neonotoids in the eastern hemisphere show some degree of variety.

Boreoids

Boreoids have more rounded (brachycephalic) skulls. Their facial bones, especially the maxilla, mandible, and zygoma, are far more gracile than basal humans. Skin color ranges from very dark to slightly dark. Their eyes are brown, their hair is black and tightly curled, and they tend to have large nostrils (probably an adaptation to heat). Boreoid females have a distinctive feature not found on Earth which is called “Steatovulvia.” The adipose tissue of the vulva is quite large by human standards, and during arousal increased blood flow gives it a very dark color. Also, Boreoid dentition is slightly derived, having one less root in the first molar on the top and bottom (one root instead of two).

Anatolicoids

The Anatolicoids feature many basal characteristics lost in the Boreoids, such as a dolichocephalic skull shape, and prominent facial bones. Along with large brow ridges and zygoma, they have by far the largest mandibles and greatest prognathism of any Zebian group. Their skin ranges from slightly dark in the north to very light in the south and west, with amber and other hues along the east coast. Their hair tends to be curly in the north but wavy or straight in the south and west. Anatolicoid dentition is also slightly different, with the first upper molar having one extra root (three instead of two).

Dyticoids

The Dyticoids represent some of the least derived humans on Zebia. They retain many features of ancestral humans, such as prominent facial bones and a narrow skull shape. The zygoma is especially pronounced. Skin tone tends to be dark, but it is much lighter along the west coast. Infant Dyticoids are born with “blue toes”, a build up of pigment that disappears a few days after birth.

Notoids

The Notoids are a highly derived form. The maxilla and mandible are more gracile than the basal human norm, but the zygoma is still pronounced. Hair is straight or wavy and black. Several features are present that seem to respond to the cold of the southern climate: stout frame, short digits, abundant body fat, epicanthic fold, and extra vellus hair (though no extra terminal hair). Smaller buttocks, noses, penises, and breasts may be responding to the same pressures, or they may not. Notoids all have sundadont dentition.

Neonotoids

The Neonotoids of the “New World” are very similar to Old World Notoids, and even more similar to each other. However, there are a few key differences. First, the Neonotoids of the eastern hemisphere north of the Antarctic region have lost some of the cold weather adaptations of their ancestors, such as small noses and digits (though their epicanthic folds remain intact). Also, skin color varies greatly in the eastern hemisphere. Most importantly, the Neonotoids on the west coast of Trita have a remarkable adaptation. For reasons that are still unclear, some of them have evolved light hair and eye coloration. Many communities in this region have a majority of inhabitants featuring brown hair, or in some rare cases even dark blonde hair. Blue or green eyes are very uncommon, but far more common than anywhere else on Zebia. There is no trace of light hair among Zebians on any other continent.