Tit for tat, thanks for that
In Darwin’s original theory, natural selection was considered to be driven by competition. This presents a problem. If it’s all about survival of the fittest, and out competing all others, why is there so much cooperation in nature? In the 1980/s, a tournament was held in which competitors sent in computer programs that would play something called “The Iterated Prisoners’ Dilemma.” The program that did the best most consistently, was one of the simplest: “Tit for Tat.” It was, and still is, an example of how things like symbiosis and cooperation could evolve.
Here are a couple of articles on “Tit for Tat,” and “The Prisoners’ Dilemma.”