We're all just one impulsive Google images search away from facing the unblinking darkness that lurks within the heart of man. But that black pit of twisted evil and decay shouldn't surprise anybody; it's rooted in our genetic makeup. Literally.
Back in biology class, you were probably taught that DNA was a sensible, organized system. When they called it "the building blocks of life," you probably pictured DNA as a series of neatly edged Legos snapping together to form a cohesive whole. When in reality, DNA is more like an old scrapbook that someone has torn up, pasted back together, filled with old newspaper clippings about murder and then taken into the bathroom with them.
She knows what she did.
A large part of this internal mess comes from the endogenous retrovirus. A normal virus works by moving into a host cell and using it to reproduce, but retroviruses reproduce by actually mixing their own genetic material with the DNA of the host cell they're invading. If a normal virus is a home invasion robber, busting down your door and smashing up your stuff, a retrovirus is the creature from Alien, impregnating you with its horrible seed and producing a twisted mockery of everything you once were, and then laughing as that atrocity murders all of your friends. Metaphorically speaking, of course.
In the distant past, retroviruses picked up by our ancestors would occasionally find their way into the sex organs, and the newly virused-up DNA was passed along to their children. As a result of all this virus-laden boning, we modern humans have about 100,000 of these microscopic gate-crashers cluttering up our DNA. When you add in the assorted genetic trash they've left behind, more than 40 percent of human DNA is made up of ancient, sinister and almost certainly cursed viruses.
Scientifically speaking, they are "the clumpy purple thingies."
But these viruses can't do much harm today, right? Oh, how we love your unflinching optimism, rhetorical question, but you're wrong again: Tests on the cerebrospinal fluid of schizophrenic patients (that's science-talk for "the brain juice of crazies") have revealed unexpectedly high levels of a particular endogenous retrovirus. This suggests that the misunderstood mental illness is, in fact, a long-term side effect of a retrovirus that we all have inside us already. It's no good locking the doors, people; that crazy is calling from inside the house.
"Get in the car. I just want to talk."
In people who are genetically inclined, this retrovirus can be "switched on" by a separate viral infection that occurs around the time of birth -- herpes, toxoplasmosis (aka Cat Zombie Disease) or even plain old influenza. Studies have found that babies born in winter months -- around flu season -- are at greater risk of developing not just schizophrenia, but bipolar disorder and multiple sclerosis later in life, suggesting that all three conditions might just be different reactions to the same retrovirus. Basically, if you catch a cold as a baby, you could end up building bombs in a shack to combat the lizard people who've infiltrated our government, and it's all thanks to the insanity that lives in everybody's blood.
5Reanimated Zombie DNA
It's not just Madness Viruses cluttering up humanity's building blocks. The useful parts of DNA, which give us things like hair color and lungs, make up only around 2 percent of the human genome. Aside from the viruses, the other 98 percent is made up of allegedly "dead" genetic material: unused DNA sequences that might have once been useful but that now have no known purpose, like the human appendix, or Utah. But much like Jason at the end of every Friday the 13th movie, it's not really dead -- it's just waiting for us to check the body so we get close enough to be murdered.
Stay back! That thing's covered in DNA!
Under certain circumstances, long-dead DNA sequences can suddenly return to life, giving their human carriers an all-you-can-catch buffet of horrible diseases. A common form of muscular dystrophy, FSHD, is caused by a "dead" gene present in all humans. But it's only "dead" because it's missing one specific sequence that allows it to be successfully transcribed. All it takes is one mutation, and the gene rises from the grave to wreak its terrible revenge on humanity.
Above: One of the hot ones.
Scientists know about FSHD because it's easy to study -- the condition can be traced back to a single, dominant gene. But it's no fluke: A gene thought to put people at risk for Crohn's disease was resurrected after being "dead" for about 25 million years. The cause of the resurrection? Another retrovirus. In other words, prehistoric killers are not only living in your skin but also can team up together, Voltron-style, to bring you down from the inside. One researcher -- we'll call him Dr. Foreshadow -- said, "Don't count a gene out until it's totally gone from a genome."
We assume he spun his chair around immediately afterward to ominously add "and maybe not even then" before disappearing in an explosion of smoke and villainous laughter.