Possibly only second to the preponderance of nautical terms, animal idioms help us to interpret the human condition. It’s understandable in a way given that their distinctive characteristics make for easy anthropomorphism.
Sometimes however the story can be less obviously accountable. We have seen earlier about ‘Raining Cats and Dogs’, and ‘Bald as a Coot’, and there are many more including these well-known ones: Red Rag to a Bull, Go the Whole Hog, Let the Cat out of the Bag, Have Kittens, Cat’s Nine Lives, Cheshire Cat, In the Doghouse, Kill Two Birds with One Stone, Rat Race and Spring Chicken. The following perhaps have less well-known explanations:
Don’t look a gift horse in the mouth
One of the methods of judging the age of a horse is to inspect its teeth and their condition. However, anyone who is given a horse as a gift should not inspect its teeth before accepting it or, at least, not in the presence of the giver.
A white elephant
This expression refers to the successive kings of Siam (Thailand) who used to give a white elephant to any courtier who had irritated them. Although the animals were held in very high esteem and even regarded as sacred, their maintenance was so expensive that any recipient was inevitably ruined.
Not enough room to swing a cat
This refers to the whip used on board ships for dealing out punishment (the whip started as a cat-of-three-tails but translated into a cat-of-nine-tails by the end of the 17C; this method of punishment continued until 1875)
To bury one’s head in the sand
This expression is based on the habit of the ostrich that is reputed to bury its head in sand when pursued and in danger in the belief that it cannot be seen. The ostrich, which is the largest flightless bird in Africa with a height of up to nine feet, in fact does no such thing. Despite their size they are extremely agile. When they sense the approach of predators, they bend their necks parallel to the ground to listen intently and, if in danger, they are able to escape by running away at speeds of up to 40 mph. They probably give the impression of burying their heads when they are seen bending their necks and listening close to the ground, or when attending to the eggs in their nests, which consist of a simple depression scraped in the sand.
An albatross around one’s neck
Nautical superstition has it that it is unlucky to kill an albatross as these birds were believed to embody the souls of departed mariners. Coleridge’s well-known poem The Ancient Mariner, first published in 1798, tells the story of a sailor who kills an albatross. When this translates into ill fortune to his ship, the dead bird is put round the neck of his shipmates as a sign of his guilt. He repents and is finally forgiven but his conscience still works upon him and the bird and the guilt stays with him in spirit.