Race
Race emerged in the last few centuries of civilization as a taxonomy for classifying human beings, and did not survive its collapse as a widely understood concept. Though human beings have identified themselves and others as members of different groups for as long as we can tell, the notion that these differences have something to do with biology only took root in the age of colonialism and only lasted for a few centuries.
#Social Construct
Biologically, a race refers to a sub-species — a group of individuals that “breed true.” For example, the yellow-rumped warbler has two races, each with a different song and color pattern. If a yellow-rumped warbler from one race mated with a yellow-rumped warbler of the other race, they could produce offspring, which would belong either to the first race, with its song and color pattern, or the other. They could never produce an offspring that would mix the characteristics of each, with the song from one race and the color pattern from the other. They “breed true,” making them actual races.
Among Homo sapiens, of course, the offspring of parents from different “races” have a mix of features from both parents — precisely the outcome that could never happen between actual, biological races.
Instead, humans have klines — traits that tend to cluster together and correlate with one another. Unlike races, klines can shift and change easily and quickly, and as they merely point to correlated traits offer no sure way to clearly classify people or predict other, less obviously visible traits that they might possess.
Despite the lack of any evidence for its reality, many people in the last centuries of civilization believed that Homo sapiens had races and treated each other as such. This widespread ignorance made race a social reality, even though it had no basis in biological reality.
#The End of Race
As civilization collapsed and the Rusting Ages began, the racism of the old world became terminal. Hard-pressed to survive, those communities which turned away potential help because of race found themselves losing much-needed talent, skills, and help for their devotion to an idea without any scientific merit. Those communities most devoted to “racial realism” perished especially quickly.
#Appearance
By the time of the Fifth World, most people descend from people of every “race” alive today. A worldwide tropical climate has eliminated the environmental pressures that might otherwise have encouraged people in one part of the world to look different from another. As a result, people in the Fifth World reflect an omni-ethnic mix. This averaging has dropped out the extremes of appearance: the very blackest black skin has disappeared, and no one in the Fifth World would really classify as “white” among their ancestors.
People in the Fifth World understand themselves as members of a particular community first and foremost. Some communities have chosen to join with other communities to form larger structures, and the members of those communities may use those terms to identify themselves as well. The notion of race, though, so crucially important to a few generations of their ancestors, has faded into obscurity, with few in the Fifth World even knowing the word.