From ScienceDaily: Survival Of The Weakest? Cyclical Competition Of 3 Species Favors Weakest As Victor
An curious study from a German university about evolution, the idea of the survival of the fittest, and game theory. As we know, "these processes increase the 'fitness' of the species overall, since, of two competing species, only the fittest would survive." In simulations, researchers pitted three cyclically competitive species against one another, so that one species is weaker than the second, but stronger than the third. Sort of like rock-paper-scissors, only scissors can't be beaten by rock; rock's a weakling. Strangely, interestingly enough, the two strongest species kill each other off, and the third weaker species survives. Rock isn't weak; he's the Heir of Slytherin. Whether the differences in strength are large or small, the third species is the winner "with very high probability."
"The Survival of the fittest" as a metaphor for natural selection has allowed for a lot of interpretation, namely as the continuing triumph of the strong over the weak. A study like shows natural selection is not that pat. "Fittest" doesn't always mean strongest/smartest/fastest/sharpest. Leading the study was Prof. Erwin Frey, who says that this study "shows once more that chance plays a big part in the dynamics of an ecosystem."
Don't discount this just because it's a simulation, because Prof. Frey recalls, "Incidentally, in experiments that were conducted a couple of years ago on bacterial colonies, in order to study cyclical competition, there was one clear result: The weakest of the three species emerged victorious from the competition."