The ancient Egyptians were no stranger to crocodiles. For people living and working near the River Nile, the threat from a snappy attack was constant. Such was the respect for crocodiles that the animal was represented in one of the ancient Egyptian gods – Sobek. It was in this culture that the phrase was born.
Crocodiles do actually cry. When they spend enough time out of the water, their eyes dry out so they weep to keep them lubricated. The belief started that the crocodiles only shed these tears when attacking and eating their victims, either as a trap to lure in their prey or out of emotion for their violent act.
The writings of ancient Greek historian Plutarch show that this concept survived through the centuries, until medieval times, even in countries where crocodiles were not found. The phrase is seen in the 14th century English publication, The Travels of Sir John Mandeville – about a knight’s adventures around the world – and also gets a couple of mentions in William Shakespeare’s canon.
Enough is known about crocodile anatomy now to know that they do not cry out of emotion or as a sinister trap, but the expression survives. Which is more than could be said about anyone who gets too close to a peckish croc.