{{quote|"Individual organisms are best thought of as adaptation-executers rather than as fitness-maximizers. Natural selection cannot directly 'see' an individual organism in a specific situation and cause behavior to be adaptively tailored to the functional requirements imposed by that situation."|John Tooby and Leda Cosmides|"The Psychological Foundations of Culture"}, 1992, pg24}
A central principle of evolutionary biology in general, and evolutionary psychology in particular.
If we regarded human taste buds as trying to maximize fitness, we might expect that, say, humans fed a diet too high in calories and too low in micronutrients, would begin to find lettuce delicious, and cheeseburgers distasteful. But it is better to regard taste buds as an executing adaptation - they are adapted to an ancestral environment in which calories, not micronutrients, were the limiting factor. And now they are simply executing that adaptation - evolution operates on too slow a timescale to re-adapt to such a recent condition....