Science appears to be venturing into a realm that dogs know well. Research is predicting that it may be possible to identify people by their odour. Speculation is that each individual emits a unique ‘odourprint’:

“Every person has a unique fragrance, similar to a fingerprint or DNA sample, which could be used to create a database of human scents, scientists said.

Eating powerful foods such as chili or garlic may change how we smell, but it does not disguise our underlying genetically-determined aroma, tests on mice have shown. Creatures who were given strong-smelling foods were still recognised by their peers.”

link: ‘Odourprinting’ could be used to identify people

What the dog may be doing when sniffing a tree or a lamp post is that it is “reading” a very unique signature. Possibly the dog knows exactly who has been there and approximately how long ago.

With respect to human beings, the dog likely knows its human family’s distinct odour. When something disrupts that signature, it may be an anomaly that disturbs the dog. It could be compared to a human’s seeing a nasty bruise on a friend’s face. The odd scent which goes against what the dog identifies as the person’s usual odour scent may be cancer. That is one hypothesis of why some dogs are upset and warn a member of their human family about the presence of an odd - and upsetting - scent.

A dog would look at this scientific speculation and might conclude that humans have so much to learn.

Catherine Forsythe