​The setting of Revelations is in almost all respects identical to that of real-world Earth...with the exception that the rise of sentience was triggered by a megavirus that spread across the globe after a meteor landed in Xiuyan, China more than 50,000 years ago. The airborne version of the virus (Pandarovirus anthrosapiens) had a 50% infection rate and a 95% fatality rate, and caused infected vertibrates during pre-pubescent growth to develop more or less humanoid physiques. There's still great variance in size depending upon the base vertibrate species. As a side note, the virus was successful in infecting approximately 0.00001% of non-invertibrate multicellular life...and as such there are some species of anthropomorphic insects and arachnids which typically live in hot, humid climates. Small animals such as mice and birds are typically 4-5.5 feet tall and weigh as little as 40 lbs, whereas large animals such as elephants and whales stand between 6.5-8 feet and weigh as much as 1000 lbs. Aquatic life-forms that were infected generally live in seaside cities, or on small floating and submerged cities that dot the oceans and lakes of the world. Because the airborne virus had such a low infection rate, the vast majority of the uninfected species still exist in their 'feral' or 'unevolved' form.

While the airborne variant of the virus died off nearly 40,000 years ago, it has thrived as a sexually transmitted disease (100% infection rate male to female, 25% infection rate female to male). While, the virus is usually (95%) fatal to those that are infected after birth, it's possible for an feral animal to father evolved offspring on a evolved mother, though such a thing is highly taboo (and illegal). Among infected 'evolved' species, the virus only sometimes (~50%) causes it's hosts to completely evolve, resulting in many of the base species traits being partially or completely expressed such as digitigrade limbs, hooves, wings (sometimes in addition to arms), multiple breasts, or seasonal breeding cycles referred to as 'heritage traits' (or other names depending on region). The virus can also cause partial transexualism (~3.1%) or full hermaphrodism (~3.1%). In some very rare cases (~0.8%), the virus completely fails to express the anthropomorphizing gene sequences, resulting in non-anthropomorphic intelligent animals called 'throwbacks'. Another small fraction (~0.8%) may fail to develop sentience and were historically called 'brutes', functioning at about the same level as a 3 year old. All these minority groups were historically discriminated against and/or taken advantage of. Now brutes and throwbacks are referred to as mentally or physically disabled, though most people still use the non-P.C. terms or worse.

Oviparous species sometimes still lay eggs, though this is always the result of heritage traits in the mother's reproductive system. There is also a trend among snakes to fail to develop legs, though this almost never inhibits their mobility. Because of the viruses aggressive chromosomal normalization (to exactly 23 pairs of chromosomes), many cross-species hybrids are possible that would normally be impossible, though unusual hybrids (e.g. reptile/mammal) are extremely rare and usually sterile. There are even (unconfirmed) reports of hybrid insect/mammal hybrids throughout history. One of the side effects of the virus is a greatly reduced fertility rate. As such, prophylactics and other anti-pregnancy measures are considered just an extra precaution against a rare occurrence. Pregnancy is almost always cause for celebration, usually on par with a wedding. Rates for identical twins are about the same, though rates of fraternal twins are about half. Sexual education includes methods of enhancing fertility and optimizing chances of pregnancy as well as preventative measures.

Society otherwise developed much the same as Earth did. Historically, Large, aggressive predators tended to become the ruling and warrior classes. Large docile herbivores tended to be used as laborers and slaves. In ancient civilizations, species closely dictated social status, and still do in many of the southern and eastern asian cultures. In northern europe following the fall of the Roman empire, much of the upper class was dominated by canines and during a period of about 400 years developed info several dozen bloodlines that very closely mimic those of modern earth dog breeds. Some of the old families still greatly value pure-blood marriages, especially in the upper class. Rates of vegetarianism are much, much higher (as much as 50% of the population) due to the prevalence of herbivorous base species and ethical/moral concerns, though all 'evolved' species are technically omnivorous. Most of the real-world discrimination based upon gender or race translates into species-based discrimination...though religious discrimination is not unheard of. Additionally, there is still discrimination against minority groups such as transsexuals, hermaphrodites, throwbacks, and brutes, though modern disability, housing, and employment laws to some degree protect them.

Many religions have recently begun to adopt the position that the megavirus (only discovered in the past two hundred years) is the work of God, due to it's impossibly complex nature compared to all other known viruses, and such theories are rapidly replacing the long-held ideologies of creationism. Some religions (e.g. Scientology) have even asserted that the virus is actually the work of an advanced alien lifeform 'creator' race. Most scientists have adopted the position that the virus was transplanted through meteoric activity from another world, though nobody has as yet traced the virus to the Xiayun meteor...if what landed there was a meteor at all.