Elephants have an ability to smell unparalleled, as far as we know, in the mammal kingdom. Dogs, known for their acute olfactory sense, are not able to distinguish nearly as many separate smells as pachyderms. Humans were shown to have a sense of smell only about 20 as accurate as that in elephants.

Olfactory Receptor (OR) genes are present in sensor cells that line the nasal cavities of mammals. A new study by Japanese researchers looked at the OR genes in 13 different mammals, including elephants and humans. They found pachyderms possess the greatest variety of these OR genes, giving the animals a distinct advantage in identifying smells.

Around 10,000 genes were examined during the study, only three of which were common to all 13 species in the study. The greatest variety were found in elephants, with around 2,000 present in their nasal cavities. Dogs were found to have about half that number, while humans and chimpanzees possess just 400 varieties of the gene.  

"Comparison of... OR genes among mammals lets us know the commonalities and differences of olfactory perception, deepening our understanding of the sense of smell in humans," Yoshihito Niimura, co-author of the study, said.

A world were people were able to detect smells as accurately as pachyderms would be highly unusual to our way of thinking. We would be able to detect food cooking from a much greater distance than we are able to in our world. A piece of chicken sauteing in a pan indoors might be detectable down the street, instead of in the next room. A barbeque could be smelled not from a few blocks away, but from the adjoining neighborhood.

We would also be able to smell one another - no matter how clean - from much further away than we can, given our low number of OR genes. This would make social interactions - especially those between potential sexual partners - far different than the norm. Instead of a slight sense of pleasure or displeasure with a person's smell, it could become as important as desirable looks. Elephants in Kenya are able to determine which group of people humans belong to, based on their scents. That ability in humans would allow us to easily identify the ethnic heritage of those we meet.

Humans domesticated dogs around 25,000 years ago, during the last great ice age. Part of the symbiosis we formed with the animals was due to their olfactory skills, which are greater than our own. Although many factors played into the domestication, if we had a better sense of smell than dogs, it is possible we may never have formed our special bond with the animals.

Of course, humans are inundated with visual stimuli, from television and billboards to neon signs and outdoor video screens. In a world of super-human smell, a whole industry of olfactory advertising could inundate human noses like Times Square bombards the eyes.

The study was published in Genome Research.