Science fiction, brought to reality. [Credit: Niko McCarty | CC BY-NC-ND]
Viruses are at the forefront of many people’s minds right now, with good reason. Truthfully, though, viruses have been at the forefront of many authors’ imaginations for years. There’s a whole sci-fi subgenre, called “plague fiction,” that depicts the collapse of civilization at the hands of an unstoppable disease. Contagion, The Andromeda Strain, Severance and most contemporary zombie stories follow this format.
But viruses, as a group, are a little more complicated than simple killing machines. Over the years, a handful of authors have attempted a more nuanced take on viral infection in fiction. Few succeed as well as Octavia Butler in her 1984 novel, Clay’s Ark.
Clay’s Ark tells the story of attempted quarantine gone wrong. Before the events of the novel, a spaceship full of astronauts makes the first-ever interstellar voyage to a planet orbiting Proxima Centauri. Things are going well until the crew succumbs to a mysterious virus that makes them feverish, super strong and extremely horny.
The ship, called Clay’s Ark, crash-lands in the California desert upon returning to Earth from Proxima Centauri. Geologist Eli Doyle is the sole survivor of this crash. Doyle is infected with the alien virus, and he attempts to slow the spread by quarantining at a nearby farmhouse. But things go pear-shaped pretty quickly.
The farmhouse was occupied before Doyle ever entered, and since the CDC didn’t update its “small gatherings” guidelines quickly enough, he soon infects the family living there. What’s more, they discover after a few months that the virus changes its host’s DNA to the point where infected people give birth to quadrupedal children who resemble sphinxes. Whoops. The story ends with (spoiler) the virus getting out and presumably infecting most of the world. It doesn’t end civilization, but it does change humanity.
Ok, here’s a truly wild fact: some viruses really do alter the DNA of their host species. But don’t fret; it’s not always a bad thing.
When a virus infects a cell, it injects a little segment of genetic code that hijacks the cell’s machinery, turning it into a virus factory. In most cases, this causes the cell to rupture and release more viruses into the body. However, certain viruses — called retroviruses — have learned how to stitch their genes into the host’s DNA rather than blow the cell up.
Retroviruses inject RNA — a single-stranded genetic template — into host cells, rather than double-stranded DNA. Using an enzyme called reverse transcriptase, the retrovirus synthesizes DNA from its RNA blueprint. Then, using another enzyme called integrase, the virus incorporates this new DNA into the host’s genetic code. Retroviruses are involved in terrible diseases, like AIDS, but sometimes they do good things, like make plants drought resistant.
Viruses have been infiltrating the human genome since before humans were a thing. Pregnancy wouldn’t be possible without leftover viral DNA. Evidence suggests that as much as 30% of the DNA separating the human and chimpanzee genome was put there by retroviruses. In a sense, viruses made us human.
The idea that a virus could alter the course of human evolution sounds strange and kind of scary. But the reality is that it’s already happened — and it’ll probably continue to happen in the future. So, you could argue that Butler, as usual, was spot-on… fortunately, we haven’t encountered any weird space viruses. Yet.