What does the hypothalamus do?

The hypothalamus lies quietly under the thalamus,* but it doesn’t mind its own business: Together with the pituitary gland, it links the nervous system to the endocrine system. In that capacity it’s quite the busybody, playing a role in fear and anger, hunger and thirst, blood pressure and pulse rate, fatigue, body temperature, and circadian rhythms. It gets involved in sex, too, processing pheromones as olfactory stimuli. Cheeky thing.

* By the way, the word hypothalamus comes from Greek roots meaning “under the thalamus”. Go figure.