Although superheroes are strictly the stuff of comic books, there are scientific explanations behind some of their origins. One Stanford scientist looks at the background of both Captain America and the Incredible Hulk and details how science explains their existences.
Alvarado looked at the origin stories of these superheroes, but realized much of the science of their creations was left out. However, Alvarado discovered that the creation of both of the superheroes could be explained through epigenetics.
Epigenetics involves switching on or off certain base pairs of DNA or RNA, which changes the DNA sequence.
Alvarado started his research with Captain America, who started life as the wimpy 90-pound weakling Steve Rogers. Rogers wanted to serve his country in World War II, but the Army turned him down. However, he gets enlisted to a super secret governmental program that eventually straps him into a chair, fills him up with chemicals called "Super Soldier Serum" and zaps him with "Vita-Rays." The result of this experiment is a tall, muscular super soldier, with super strength, super intelligence and super stamina.
To create a real-life Captain America, Alvarado researched specific genes discovered for increasing muscle and improving the body's circulatory system. We now have ways of turning these genes on or off, so creating a super soldier like Captain America isn't as far-fetched as it seems.
"We have a lot of genome-editing tools - like zinc finger nucleases, or CRISPR/Cas9 systems - that could theoretically allow you to epigenetically seek out and turn on genes that make your muscles physically large, make you strategically minded, incredibly fast, or increase your stamina," says Alvarado.
Alvarado's scenario involves packaging chemicals with these DNA instructions into capsules and delivering them via injection. These drugs respond when a certain wavelength of light, or Vita-Rays, hits the subject, triggering the DNA instructions to carry out their tasks.
So what about the Incredible Hulk? Can a dose of radiation turn a man into a hulking green beast every time he gets angry?
First, Alvarado considered the effects of gamma radiation on DNA. A large amount of radiation, such as the one Bruce Banner, aka the Incredible Hulk, received would result in the breakdown of the DNA's helix. Although the body can repair this after small amounts of radiation, a larger dose would make those repairs "sloppy," and allow for new commands, including epigenetic switches that are written into the DNA. Those switches might command Banner to become the Hulk when he becomes angry.
As for the Hulk's signature green skin, Alvarado has a simpler explanation: bruising.
"Bruce Banner's transformation into the Hulk would be incredibly traumatic to his body, and maybe his green skin is the result of a whole-body bruise," says Alvarado. "If you want to get really creative, maybe his blood is full of some sort of green Hulk-oglobin, which can carry more oxygen to the muscles than hemoglobin and gives him his strength and stamina."