In contrast to traditional psychology, which focuses on mechanisms, evolutionary psychology focuses on functions. Functional questions about learning, cognition, emotion, and other psychological phenomena can be addressed by one of two methods: reverse engineering or planned comparisons. The former evaluates whether or not a trait's features instantiate an efficient design for meeting the hypothesized function. The latter evaluates whether or not the distribution of the trait matches the demand for the hypothesized function. Because evolution maximizes the rate of gene transmission to future generations, psychological aspects of reproductive strategy are likely to have been targets of strong selection, and hence are profitable topics of scrutiny by evolutionary psychologists.