Here's a breakdown:
* Physiological connection: When we get angry, our bodies react physically. Our heart rate increases, our blood pressure rises, and we might feel a surge of heat in our face and head.
* Metaphorical association: Over time, people started using "heat" metaphorically to describe strong emotions like anger.
* Historical context: The association between heat and anger is found in many cultures. For example, ancient Greek philosophers believed that the four elements (fire, water, earth, and air) were associated with the four humors (blood, phlegm, black bile, and yellow bile) that determined a person's temperament. Fire was associated with anger and choler, the "hot" humor.
Therefore, the expression "hot-headed" likely evolved from this association of physical heat with strong emotions and became a way to describe someone who is easily angered or prone to impulsive actions driven by passion.