Dog

The dog is a domesticated descendant of the wolf and the oldest domesticated animal. The pattern of ridges on a dog's nose is unique to each dog, like a human fingerprint, and has been used to identify dogs.^[1] A dog leaving nose prints on a window is therefore signing it.

Smell

A dog's sense of smell is many thousands of times more sensitive than a human's. A dog's nose has up to hundreds of millions of scent receptors, compared with a few million in a human nose, and a large part of its brain is used to make sense of smells.^[2] When a dog sniffs a lamppost for several minutes it is, in effect, reading the newspaper, including the letters page.

Dogs' noses are wet because they produce mucus that helps trap scent. A dry nose does not necessarily mean a dog is unwell, a fact that has relieved millions of dog owners and never once relieved the dog, which was fine all along.

Understanding

Dogs understand pointing better than almost any other animal, including chimpanzees. If a person points at something, most dogs will look at the thing rather than at the finger. Cats will look at the finger, then at the person, and then leave.

See also

• Cat – which does not look where you point
• Lamppost – its newspaper
• Sock – a frequent target

References

1. Sniff, S. (2005). The Nose Knows. Kennel Press.
2. Snout, P. (2012). “Hundreds of Millions of Receptors”. Journal of Smells 3: 1.
3. Point, P. (2001). “Look at the Thing, Not the Finger”. Pet Cognition 1: 1.