Keeping Up With the Red Queen

 
 

There have been plenty of moments throughout my first two years as a PhD student when I felt like it took all of my ingenuity, energy, and effort to maintain mediocrity. Where the same level of productivity as an undergraduate would have earned me rewards like high grades and a strong sense of accomplishment, it’s now only just enough to keep me afloat – never comfortably ahead and always at the risk of falling behind.

This is not an uncommon feeling, and it’s not unique to graduate students either. In fact, the very idea of running in place without moving forward forms the basis of a well-known and thoroughly discussed theory in evolutionary biology: the Red Queen hypothesis. One reason this hypothesis has attracted so much attention is that it explains a scientific idea with an analogy pulled straight from classic children’s literature.

The Red Queen, after whom the hypothesis is named, is one of the main characters of Lewis Carroll’s Through the Looking-Glass, the sequel to Alice’s Adventures in Wonderland. Not to be mistaken for the beheading-happy Queen of Hearts from the first novel, the Red Queen is a complex character who deserves some closer examination.

The Red Queen is the first main character Alice encounters after she crosses through the looking-glass above her fireplace to an alternate reality. Alice leaves her house in this alternate universe and meets the Red Queen in the garden. The Red Queen, who is the physical representation of an oxymoron, delivers some self-contradictory lines of dialogue. She then proceeds to take Alice’s hand and run. Alice notices that as fast as they are running, the scenery around them doesn’t change, and they end up under the very same tree where they had started. When Alice points out this anomaly, the Red Queen responds,

“Now here, you see, it takes all the running you can do, to keep in the same place. If you want to get somewhere else, you must run at least twice as fast as that!”

The reader is meant to interpret this idea as complete nonsense, but it sounds like natural selection to me. In an environment that has limited resources and is subject to constant change, organisms must adapt to their surroundings in order to out-compete other organisms and successfully produce the next generation of their kind. Those who can adapt to current environmental conditions the best and quickest will typically outlive the stragglers. In other words, it takes all the running you can do just to survive.

The University of Chicago’s Leigh Van Valen saw logic in Carroll’s nonsense, and published the Red Queen hypothesis in his 1973 paper, “A New Evolutionary Law.” Van Valen used the Red Queen hypothesis to address one particular question: why do all species in the paleontological record appear to go extinct at the same rate, with no particular species able to elude extinction any longer than any other species? He proposed that in the constant struggle for existence, every species is competing in an evolutionary arms race where one species doesn’t take the lead for long. This idea was so revolutionary at the time that Van Valen could only publish it in a journal of his own making, called Evolutionary Theory.

Scientists have since expanded on the applications of the Red Queen hypothesis, using it to explain the co-evolution of parasites and their hosts, and even why sexual reproduction evolved in the first place. It turns out that sex as we know it may not have ever occurred if not for a little pressure from parasites.

Sexual reproduction is a tiresome process, and it’s not the smartest strategy out there to pass genes on to the next generation. On the other hand, asexual reproduction creates offspring that are genetically identical to a single parent – essentially a clone. Without spending time and energy looking for a mate, asexually reproducing organisms can produce more offspring more quickly than by sexual reproduction.

The catch is that genetically identical clones are vulnerable to parasites. Parasites have short lifespans and reproduce so rapidly that they can evolve quickly within a single host. If that host reproduces asexually, its offspring are vulnerable to the same parasites. An entire population of clones could be wiped out by a parasite, given their lack of genetic weaponry for self defense in the evolutionary arms race.

If, however, the host reproduces sexually, it can combine genes from itself and a genetically different parent to create offspring with unique DNA. It’s possible that within the jumble of mixed-up genes inherited from both parents, there could be a gene that makes the offspring resistant to parasites. While parasites can evolve to break through a host’s defenses, at least the offspring have a head start in the co-evolutionary arms race. And the parasites need to adapt to new, genetically unique host every generation. So, sexual reproduction conveys its own selective advantage in evolution.

How could Lewis Carroll have possibly inspired such a theory with his Red Queen – and in a children’s novel? Through the Looking-Glass is a prime example of literary nonsense. The novel is set in an alternate reality. The Red Queen’s running in place could represent something the author does not expect to happen in reality. Lewis Carroll, while famous for his Alice novels, was first and foremost a mathematician known as Charles Dodgson. He took a conservative approach to mathematics, and his Alice novels have been interpreted as his own personal satire of emerging ideas within the field in the 19th century. Such ideas were abstract in nature, consisting of imaginary numbers and symbolic algebra. Each ridiculous, self-contradictory event that occurred in Alice’s Adventures in Wonderland or Through the Looking-Glass was a criticism of an abstract mathematical idea that Carroll considered to be complete nonsense. The Red Queen hypothesis that was inspired by literature was in turn inspired by mathematics. Regardless of where exactly its roots came from, the Red Queen hypothesis will always be known as science inspired by nonsense.