Tunguska Event
The sudden appearance of unusual abilities in humanity during the late 1930's can be traced to the Tunguska Event of 1908, though the world at large remains completely unaware of this fact

On June 30th 1908, a comet exploded approximately 5 miles above the ground in the Tunguska forest north of Siberia while traveling at an estimated speed of 40 miles per second. An air wave generated by the blast circled the earth twice, with the dust creating unusual sunsets and other atmospheric effects all over Europe.

The explosion produced surface temperatures of 160 degrees Fahrenheit and was as powerful as a 100 megaton hydrogen bomb, larger than any built by mankind. The blast knocked down trees within a 20 mile radius and left no crater or meteoric debris.

A concentration of ablation products (like iron oxide and glassy spheres of fused rock) stretched on a "tongue" 150 miles northwest of the impact site, which would indicate that the comet probably approached from a southeasterly direction. Iridium was found in a peat layer 1 foot below the surface at the site.

The comet itself is believed to have been small, perhaps only 100 to 300 feet in diameter, which would explain why no astronomical sightings were made prior to the impact.

(Note: this actually occurred in the real world, though not everyone agrees it was caused by a small comet. In the Meta-Earth campaign, the Tunguska event wasn't caused by a comet. It was caused by something else entirely. Something which changed the world forever. To find out what actually occurred keep reading.)

The Big Crunch
There are an infinite number of universes besides our own. The Big Bang is the one common origin to them all. All of these "Multiverses" are interlinked in some unknown way.

These universes are constantly expanding, propelled forward by the initial force of the Big Bang. Eventually the universes lose momentum and start to contract. This is called the Big Crunch, the end of time, where everything in the universe is collapsing in upon itself.

In theory, when the Big Crunch occurs in a universe the cycle should renew itself, with the formation of yet another universe. This is what generally occurs, but there have been times in the multiverse when a universe has imploded upon itself and instead of creating a new universe the Primordial energies of that universe have been "shunted" to another universe, altering it in unpredictable ways.

This has occurred at least twice in the campaign universe. The first time it occurred was before the dawn of recorded history. The Primal forces gave rise to Magic and many other supernatural phenomena. Over time these forces diminished, and gradually faded away from mainstream existence.

The second, and most recent time, it occurred was in 1908. The Primal Forces that were released into this reality resulted in the Tunguska Event on Earth which gave rise to superhuman powers and abilities.

Historians note that since the birth of "metahumanity," the abilities exhibited by metahumans have become more varied and powerful with each new generation. Initially, only a small percentage were changed.  Most of the people who were changed were altered on a genetic level and never realized they were different. Others found that they had gained some minor, unusual ability.

These abilities helped give credibility to the Spiritualist movement and confounded Harry Houdini who was unable to disprove these abilities. During the 1920's these minor abilities helped some "Mystery Men" in their war on crime. It wasn't until the late 1930's, when the second generation metas started becoming active as "superheroes", that people with powers and abilities only read about in myths and fairy tales began to appear.

The age of the superman had arrived.

The Metagene
The strange extradimensional energy released in the explosion spawned the metagene, a mutated DNA cluster with an anomalous triple helix composition. The metagene remained undiscovered until 1986, and since then scientists have been able to discern the following about it's behavior. Those in whom the metagene is active ("metahumans") have the tendency to develop unusual abilities (more popularly called "super powers"). This activation of the metagene may occur on its own or via artificial stimulation. Those rare few who are born with active super abilities are termed "mutants." Those who don't have the metagene will never possess superpowers. Those who do have it may or may not manifest superpowers, but it is impossible to have superpowers without possessing the gene. It is hypothesised that in the vast majority of humanity, the gene remains dormant and harmless, however this cannot be proven since the latent metagene is undetectable by testing procedures. The metagene can only be detected once it becomes active.
 
There is some data that indicates an individuals abilities are somehow linked to specific psychological traits and characteristics of the individual in question. This is not a hard and fast rule, but it stands up to casual investigation. (i.e. a fireman receiving fire-based powers rather than cold-based) Other data suggests a link between the powers and the triggering event. ( i.e. getting struck by lightning causing the manifestation of electrical powers) Both of these theories are still under study, and both are inconclusive at the moment.

The awakening of the metagene may occur anytime from adolescence onwards. Awakenings are usually triggered when the individual suffers a traumatic experience. Physical side effects associated with a naturally awakened metagene are rare, and tend toward discoloration of the hair or skin. More harmful physical side effects are very rare. Psychological side effects are perhaps more frequent, though still unusual. Paranoia, megalomania, feelings of invincibility and a host of other mental conditions have been known to occur and are under study at this time. The metagene is a passive genetic trait, and can only be passed on to a person's offspring if the other parent has the metagene as well.

In a worldwide census, the majority of metahumans were found to be in the US, with Europe a distant second, and Russia and Africa third. Accurate statistics regarding the number of Asian metahumans is unavailable, due to the Chinese government's unwillingness to release such information.

It can be said that the world has roughly five thousand Supers (about one in a million). These are spread throughout the world according to the guidelines above. It can be safely assumed however that the world has a good mix of supers from all nationalities and backgrounds.

Superpowers
No one knows exactly how metahuman powers work; only that there is some link between the metagene and superpowers. Metahumans routinely break laws that no one believed could be broken-by anybody or anything. Name a physical constant or law: inertia, mass, gravity, or what have you, and some meta has already bent, twisted and broken it... and made it look easy.

Metas alternately fascinate and disgust scientists. There is a perverse feeling of wonder and horror that only scientists can feel, in watching everything they thought they knew being ripped to pieces by watching a man fly, lift a truck, or move objects with his mind.

Studies of metahuman abilities hint at the mechanics behind these strange occurrences, but no definitive proof of just how the hell they are doing these things (that no one is supposed to be able to do) is ever found. All the scientists can do is document how much metahumans warp reality with their powers.
      
So far, no one, not even the Metas know how they are doing “it.”