Who Are The Snazziest Sniffers in the Animal Kingdom?

dog-450083_640It thrills me whenever I approach an animal that I don’t know as the first thing they do is waggle their nose in my direction, nostrils flaring, sniffing me out and trying to work out whether I’m friend or foe. I notice that my cat does this with inanimate objects too. If something new is added to the house, or if something has moved, or is where it shouldn’t be, the first thing she will do is sniff it. It must be her primary sense, or maybe the quickest and most reliable sense to help her ascertain whether said object is safe to be around or not.

man-426985_640We’ve all heard that in comparison to non-human animals, the human sense of smell is fairly poor. Even the magical, astutely trained and experienced noses of perfumers are pretty far down the scale of sniffing-ability in comparison to some of our animal friends. As someone interested in fragrance, I’ve had to develop my sense of smell consciously, and it’s taken some work. I know I still have a lot of training to do, even though I reckon in comparison to the average Joe, I smell pretty well! Women also have a keener sense of smell than men, apparently. This is backed up by my own (non-scientific) observations that I can tell Olly’s shirts sometimes need washing well before he’s even aware of a problem. Eeeeuuwww!

elephant-111695_640Now, if I was an African Elephant, I’m not sure I would be able to cope with Olly’s shirts at all. The African Elephant trumps all other mammals: not only does it have an extremely long proboscis, which is necessary for smelling out predators, amongst other things, but scientists have also found out that it has the largest number of olfactory receptor (OR) genes in a study of thirteen placental mammals. A whopping 1948 OR genes.

This research was undertaken in Japan by Yoshihito Niimura, Atsushi Matsui and Kazushige Touhara of the University of Tokyo’s Department of Applied Biological Chemistry, and their findings were published in the journal Genome Research. You can read more detailed information about the study here and here. You can also read the original article here.

So, where do we humans end up amongst a list of animals with superior schnozzes? How many OR genes do we have? A mere 396. Here is the list of the thirteen mammals that the researchers studied, in descending order of the number of OR genes each animal has:

Elephant 1948

Rat 1207

Cow 1186

Mouse 1130

Horse 1066

Dog 811

Guinea Pig 796

Rabbit 768

Human 396

Chimpanzee 380

Marmoset 366

Macaque 309

Orangutan 296

You can see that primates fare quite badly in the OR gene stakes, and while we humans are near the bottom of the list, poor Orangutans would probably not make very good perfumers at all.

roe-deer-110068_640Why is the sense of smell so important to mammals? The authors posit that

“…the sense of smell is critical to all mammals, and they use it for sniffing out food, avoiding predators, finding mates and locating their offspring.” (quote sourced from this article)

And why is an elephant’s sense of smell so incredible?

“The large repertoire of elephant (smell) genes might be attributed to elephants’ heavy reliance on scent in various contexts, including foraging, social communication, and reproduction.

African and Asian elephants possess a specific scent gland, called the temporal gland, behind each eye, and male elephants exude an oily secretion during annual mating, which is characterized by increased aggressiveness and elevated levels of testosterone .

Research has also shown that elephants have well-developed olfactory systems that include large olfactory bulbs and large olfactory areas in the brain.

And previous studies have revealed that African elephants can reportedly distinguish between two Kenyan ethnic groups—the Maasai, whose young men demonstrate virility by spearing elephants, and the Kamba, who are agricultural people that pose little threat to elephants, through smell.” (quote sourced from this article)

cows-nose-503999_640Relatively speaking, why is the human sense of smell so poor? One idea is that, as our posture became more upright over the course of evolution, we

 “…lifted our noses far from the ground where most smells originate, diluting scent molecules in the air.” (quote sourced from this article)

ginger-cat-253731_640But where does my cat fit into all this? I don’t know. The study doesn’t mention how many OR genes cats have, sadly. But a brief bit of research on Wikipedia tells me the following about a cat’s sense of smell:

“A domestic cat’s sense of smell is about fourteen times as strong as a human’s. Cats have twice as many receptors in the olfactory epithelium (i.e. smell-sensitive cells in their noses) as people do, meaning that cats have a more acute sense of smell than humans. Cats also have a scent organ in the roof of their mouths called the vomeronasal (or Jacobson’s) organ. When a cat wrinkles its muzzle, lowers its chin, and lets its tongue hang a bit, it is opening the passage to the vomeronasal. This is called gaping, “sneering”, “snake mouth”, or “flehming”. Gaping is the equivalent of the Flehmen response in other animals, such as dogs, horses, and big cats.”

It’s all rather humbling really. I guess we’ll just have to console ourselves with the knowledge that non-human animals aren’t able to make perfume, yet. So we’ve got one up on them there. But if they could make perfume, and did, would we even be able to smell or appreciate the wonderful creations that they might produce with their superior sense of smell? I’ll leave you to ponder that question…

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2 thoughts on “Who Are The Snazziest Sniffers in the Animal Kingdom?

    • Indeed Al! I love that Wittgenstein quote. Reminds me of when humans are looking for life on other planets and celestial bodies… No one ever seems to think of the possibility that we might not be able to recognise it. It might look, feel, taste, sound and smell totally different to life as we know it.

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