Cognitive biases are influenced by evolution and natural selection pressure. Some are presumably adaptive and beneficial, for example, because they lead to more effective actions in given contexts or enable faster decisions, when faster decisions are of greater value for reproductive success and survival. Others presumably result from a lack of appropriate mental mechanisms, i.e. a general fault in human brain structure, from the misapplication of a mechanism that is adaptive (beneficial) under different circumstances, or simply from noisy mental processes. Despite several decades of effort, no comprehensive theory of what creates these biases has emerged.