There is no single “best sniffer” in the animal kingdom, but one contender is the Gambian pouched rat (Cricetomys gambianus, a species of African pouched rat), which can learn to sniff out landmines and has been used to diagnose tuberculosis in humans. (Photo by Farinosa via Getty Images)
The ability to detect scents is vital for survival in the wild, from hunting for food to finding a mate and evading predators.
But which species takes the lead in terms of olfactory power? It turns out the answer to this question is not so simple.
Matthias Laska, a zoologist who studies sensory abilities at Linköping University in Sweden, told Live Science in an email that there are about 5.8 million odor molecules, and each of these substances can be combined to create virtually endless aromatic mixtures.
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“Because only a small fraction of these substances have been tested on any one species so far, any generalization that species A has a 'better sense of smell' than species B would simply be unscientific,” Laska said.
One of the challenges in identifying the best smellers is how difficult it is to study olfaction in general. According to the book on the neuroscience of olfaction, Olfaction in Animal Behavior and Welfare (CABI, 2017), research into olfaction lags far behind that of vision, hearing, taste, or touch. Unlike other sensory stimuli, odors are difficult to control or measure—they travel unpredictably, behave differently in air and water, and have vastly different chemical properties.
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However, the researchers have found some interesting clues about which species might be the best smellers. One important aspect is the number of olfactory receptor genes — DNA sequences that make proteins in the nose that bind to odor molecules.
In a 2014 study published in the journal Genome Research, scientists counted the olfactory receptor genes of several mammal species and found that African elephants have the most, with a whopping 1,948. By comparison, humans have just 396 genes, dogs have 811, and rats have 1,207. This makes sense, since elephants rely on their exceptional sense of smell to find food, recognize kin, detect predators, and identify short windows of time when a mate is ready to mate.
Sourse: www.livescience.com
