The Nose Knows: What Elephants Can Tell Just by the Smell


Elephants have such a good sense of smell that they can choose large quantities of food over small quantities just by smelling it, a study found.

The study was conducted by Professor Joshua Plotnik (Hunter College), along with researchers from Cambridge University and the conservation group Think Elephants International.

The research was done using Asian elephants in a Thai tourism facility with high animal-welfare standards. Two buckets of sunflower seeds in varying ratios and amounts were presented to the elephants. They could sniff the contents through small holes in the locked lids but they couldn’t see inside. When the containers were presented again with unlocked lids, “the elephants consistently chose the quantity that had more over less,” Plotnik told The New York Times. A video shows one elephant sniffing each bucket briefly, then unhesitatingly thrusting her trunk into the bucket with more seeds.

The bigger the difference in quantity between the two buckets, the more accurate the elephants’ choices were. The experiment was repeated in various ways to ensure that factors like residual smells did not affect results. One test presented different quantities at the same height to make sure they weren’t just smelling seeds piled higher and closer to their trunks. In that test, the elephants still chose the larger quantity in 19 of 24 trials.

Many species–including humans–use sight to differentiate quantity when presented with large and small amounts of food. Such decisions are important to species survival. The researchers note that a lot of animal cognition research is biased toward species that rely on vision. This study calls attention to the need for research that accounts “for differences in sensory perspective.” In elephants, for example, smell, hearing, and touch are more dominant than sight.

A lingering question is just how the elephants used their sense of smell to essentially do math by making what Plotnik calls “relative quantity judgments.” Future research, the study said, might investigate “the precise mechanisms that elephants and other olfactory animals use to discriminate quantities, and the ecological significance of such an ability.” Perhaps that sense of smell helps them “make important foraging and social decisions from far-enough distances so as to mitigate potential risk in human-dominated landscapes.” Research on wild elephants could also yield different results from this study, and could help mitigate conflict between humans and elephants in Asia and Africa.

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Elephants have a nose for quantity
Proceedings of the National Academy of Sciences, 2019

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Joshua Plotnik (Assistant Professor, Psychology) | Profile 1

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Hunter College