The origin of the phrase is a bit unclear, but there are several theories:
1. The literal meaning:
- Babies are born with their ears covered in vernix caseosa, a white, cheesy substance that protects their skin during pregnancy. This could be the literal reason for the phrase, as someone "wet behind the ears" could be likened to a newborn baby.
2. Animal husbandry:
- Another theory suggests the phrase originates from the practice of cleaning and milking cows. New calves often have wet ears from licking themselves, and an experienced milker could easily tell a young calf from an older one by its wet ears.
3. Maritime origins:
- A third theory suggests the phrase originated from the seafaring world. Sailors who were new to the sea often had their ears wet from the constant spray of saltwater.
4. Ear infections:
- Some speculate that the expression might be related to ear infections, which are common in children. The ears of a child with an ear infection might be wet and sore, leading to the association with inexperience and vulnerability.
While the exact origin of the phrase is unknown, it's clear that it has been around for centuries and is still commonly used today. Its enduring popularity likely stems from its simple and evocative imagery, effectively conveying the idea of someone lacking experience and knowledge.