Four Fs (evolution)

In evolutionary biology, people often speak of the Four Fs which are said to be the four basic drives or mind states that animals (including humans) are evolutionarily adapted to be good atFact|date=April 2007: fighting, fleeing, feeding, and reproduction. The last of these is not literally an "F" word, of course, and is a tongue-in-cheek reference to fucking or fornication.

The hypothalamus plays a major role in regulating these four basic biological needs. Researchers have shown that when lesions are made in the lateral (side) sections of the hypothalamus, animals will no longer want to eat and will even starve if not fed intravenously. Conversely, when the hypothalamus is stimulated with electrical stimulation (which activates the hypothalamus) animals will eat more and gain weight.