Here's how it likely evolved:
* Ancient Roman Superstition: The Romans believed that a small, invisible creature called a "flamma" (meaning "flame") would sit on your shoulder and whisper bad things about you to others. This whispering would cause your ears to burn.
* Transfer of Meaning: Over time, the belief in the "flamma" faded, but the idiom persisted. It transitioned from a literal explanation for burning ears to a metaphorical way of saying that someone was talking about you.
* Folklore and Legend: Many cultures share similar beliefs and idioms around burning ears. For example, in Greek folklore, it was believed that the "daemon" (a spirit) was responsible for carrying gossip and causing ears to burn.
Therefore, "ears must be burning" became a way to express the feeling that someone was talking about you, even if you couldn't hear them. It's a common idiom today, reminding us of ancient beliefs about gossip and invisible spirits.