Red Queen Hypothesis

The Red Queen hypothesis is an evolutionary theory proposed by biologist Leigh Van Valen in 1973, holding that species must continually adapt and evolve not to gain a lasting advantage but simply to maintain their existing fitness relative to the other species they interact with and co-evolve against, such as predators, prey, parasites and competitors. Van Valen named the idea after the Red Queen's remark to Alice in Lewis Carroll's Through the Looking-Glass, that it takes all the running one can do to stay in the same place, and originally proposed it to explain his own observation that the probability of extinction for a species appears roughly constant over time regardless of how long that species had already existed, a pattern he called the Law of Extinction. The hypothesis has since been extended well beyond its original context, most notably as one of the leading explanations for why sexual reproduction persists despite its costs, on the grounds that the genetic recombination it provides helps a host population keep pace with rapidly evolving parasites.