The term "crocodile tears" refers to insincere sadness. This term has an etymology dating back several centuries. As early as the fourth century, crocodile tears are referenced in the literature with the meaning of insincere sorrow. It is said that crocodiles weep while eating their hunted animals because they are sad; however, this sadness is not honest.
The term crocodile tears became widely popular after it was documented in a fifteenth-century book titled The Voyage and Travel of Sir John Mandeville, Knight. A passage from the book reads: "These crocodiles kill men and they eat them weeping."
As you may already know, crocodilians(鳄目动物) likely feel bad about little—especially feeding. However, the assumption of the crocodile-tears metaphor may be true. In a 2007 paper published in BioScience titled "Crocodile Tears: And they eat them weeping", researchers observed 7 crocodilians in cages during feeding time at a reserve (4 caimans and 3 American alligators). The researchers observed the crocodilians outside of water at feeding stations to better find out whether tearing developed.
Five of the 7 crocodilians developed something like tears in their eyes before, during or after feeding. The researchers suggest that these crocodile tears occur because a crocodilian hisses (发出嘶嘶声) while it eats, and this hissing forces air through the spaces in the bone behind the nose and out the eye, in the process picking up nasolacrimal secretions (鼻泪管分泌物.)
In humans, crocodile tears is a medical condition that causes a person to tear up while eating. Crocodile tears typically occur because of a temporary loss of facial control due to damage of the facial nerve. Specifically, when the facial nerve grows again, it does so incorrectly thus resulting in tears during chewing food.
